Patent Publication Number: US-2022224433-A1

Title: Optical Multiplexer/Demultiplexer Module and Associated Methods

Description:
CLAIM OF PRIORITY 
     This application is a continuation application under 35 U.S.C. 120 of prior U.S. application Ser. No. 16/510,829, filed Jul. 12, 2019, which claims priority under 35 U.S.C. 119(e) to each of: 1) U.S. Provisional Patent Application No. 62/697,344, filed Jul. 12, 2018; 2) U.S. Provisional Patent Application No. 62/698,856, filed Jul. 16, 2018; and 3) U.S. Provisional Patent Application No. 62/722,443, filed Aug. 24, 2018. The disclosure of each above-identified application is incorporated herein by reference in its entirety for all purposes. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to optical data communication. 
     2. Description of the Related Art 
     Optical data communication systems operate by modulating laser light to encode digital data patterns. The modulated laser light is transmitted through an optical data network from a sending node to a receiving node. The modulated laser light having arrived at the receiving node is de-modulated to obtain the original digital data patterns. Therefore, implementation and operation of optical data communication systems is dependent upon having reliable and efficient mechanisms for transmitting laser light and detecting laser light at different nodes within the optical data network. In this regard, it can be necessary to convert data streams from an electrical domain to an optical domain, and vice-versa, and transmit data streams between various physically distributed computing systems. It is within this context that the present invention arises. 
     SUMMARY 
     In an example embodiment, a data communication system is disclosed. The data communication system includes a rack switch, a TORminator module, downlink optical fiber, an uplink optical fiber, and a SmartDistribuTOR module. The TORminator module is electrically connected to the rack switch. The TORminator module is configured to convert a number (N) of downlink data communication electrical signals received from the rack switch into corresponding N downlink data communication optical signals. The value of N is greater than one. Each of the N downlink data communication optical signals has a different optical wavelength. The TORminator module is configured to simultaneously direct the N downlink data communication optical signals to a first downlink optical port. The TORminator module is configured to generate N different wavelengths of continuous wave laser light and simultaneously direct the N different wavelengths of continuous wave laser light to the first downlink optical port. The TORminator module includes a first uplink optical port. The TORminator module is configured to convert N uplink data communication optical signals received through the first uplink optical port into N uplink data communication electrical signals. The TORminator module is configured to transmit the N uplink data communication electrical signals to the rack switch. The downlink optical fiber has a first end optically coupled to the first downlink optical port of the TORminator module. The uplink optical fiber has a first end optically coupled to the first uplink optical port of the TORminator module. The SmartDistribuTOR module has a second downlink optical port, a second uplink optical port, N server downlink optical ports, and N server uplink optical ports. The downlink optical fiber has a second end optically coupled to the second downlink optical port. The uplink optical fiber has a second end optically coupled to the second uplink optical port. The SmartDistribuTOR module is configured to respectively direct the N downlink data communication optical signals and the N different wavelengths of continuous wave laser light received through the second downlink optical port to the N server downlink optical ports. The SmartDistribuTOR module is configured to simultaneously direct N uplink data communication optical signals received through the N server uplink optical ports to the second uplink optical port. 
     In an example embodiment, a method is disclosed for controlling data communication. The method includes receiving a number (N) of downlink data communication electrical signals from a rack switch at a TORminator module. The value of N is greater than one. The method also includes operating the TORminator module to convert the N downlink data communication electrical signals into corresponding N downlink data communication optical signals. Each of the N downlink data communication optical signals has a different optical wavelength. The method also includes operating the TORminator module to simultaneously direct the N downlink data communication optical signals to a first downlink optical port of the TORminator module. The method also includes operating the TORminator module to generate N different wavelengths of continuous wave laser light. The method also includes operating the TORminator module to simultaneously direct the N different wavelengths of continuous wave laser light to the first downlink optical port of the TORminator module. The method also includes operating the TORminator module to receive N uplink data communication optical signals through a first uplink optical port of the TORminator module. The method also includes operating the TORminator module to convert the N uplink data communication optical signals into N uplink data communication electrical signals. The method also includes operating the TORminator module to transmit the N uplink data communication electrical signals to the rack switch. 
     In an example embodiment, an optical multiplexer/demultiplexer module is disclosed. The optical multiplexer/demultiplexer module includes a downlink optical port, an uplink optical port, a number (N) of server downlink optical ports, N server uplink optical ports, an optical demultiplexer, and an optical multiplexer. The optical demultiplexer is configured to separate N downlink data communication optical signals received through the downlink optical port based on optical wavelength. The optical demultiplexer is configured to respectively direct the N downlink data communication optical signals to the N server downlink optical ports. The optical demultiplexer is configured to separate N different wavelengths of continuous wave laser light received through the downlink optical port based on optical wavelength. The optical demultiplexer is configured to respectively direct the N different wavelengths of continuous wave laser light to the N server downlink optical ports. The optical multiplexer is configured to aggregate N uplink data communication optical signals received through the N server uplink optical ports onto a single optical waveguide optically coupled to the uplink optical port. 
     In an example embodiment, a method is disclosed for operating an optical multiplexer/demultiplexer module. The method includes receiving a number (N) of downlink data communication optical signals through a downlink optical port. The method also includes separating the N downlink data communication optical signals into N separate optical channels. The method also includes receiving N different wavelengths of continuous wave laser light through the downlink optical port. The method also includes separating the N different wavelengths of continuous wave laser light into the N separate optical channels. The method also includes respectively directing the N separate optical channels to N server downlink optical ports. The method also includes respectively receiving N uplink data communication optical signals through the N server uplink optical ports. The method also includes aggregating the N uplink data communication optical signals onto a single optical waveguide optically coupled to an uplink optical port. 
     In an example embodiment, an electro-optical interface module in disclosed. The electro-optical interface module includes an optical fiber interface configured to optically couple to a first optical fiber and a second optical fiber. The electro-optical interface module also includes an electronic-photonic chip that includes a first optical coupler and a second optical coupler. The first optical coupler is configured and connected to receive light transmitted through the optical fiber interface from the first optical fiber. The second optical coupler is configured and connected to direct light through the optical fiber interface to the second optical fiber. The electronic-photonic chip includes a downlink polarization control device configured to split light received through the first optical coupler into a first polarization of light and a second polarization of light. The electronic-photonic chip includes a downlink data receiver device configured and connected to receive light from the downlink polarization control device. The downlink data receiver device is configured and connected to filter downlink modulated light from the light received from the downlink polarization control device and convert the downlink modulated light into a downlink electrical data signal. The downlink data receiver device is configured and connected to direct unmodulated continuous wave light received from the downlink polarization control device to an optical output of the downlink data receiver device. The electronic-photonic chip includes an uplink data modulator device configured and connected to receive the unmodulated continuous wave light from the optical output of the downlink polarization control device. The uplink data modulator device is configured and connected to imprint an uplink electrical data signal on the unmodulated continuous wave light to generate uplink modulated light. The uplink data modulator device is configured and connected to direct the uplink modulated light to the second optical coupler. The electronic-photonic chip also includes an electrical input/output block configured and connected to receive the downlink electrical data signal from the downlink data receiver device and direct the downlink electrical data signal to circuitry external to the electronic-photonic chip. The electrical input/output block is configured and connected to receive the uplink electrical data signal from circuitry external to the electronic-photonic chip and direct the uplink electrical data signal to the uplink data modulator device. 
     In an example embodiment, a method is disclosed for operating an electro-optical interface of a server. The method includes receiving downlink light through a first optical coupler, where the downlink light includes downlink modulated light of a first wavelength and unmodulated continuous wave light of a second wavelength. The method also includes filtering the downlink modulated light from the downlink light. The method also includes converting the downlink modulated light into a downlink electrical data signal. The method also includes transmitting the downlink electrical data signal to processing circuitry. The method also includes imprinting an uplink electrical data signal on the unmodulated continuous wave light to generate uplink modulated light. The method also includes transmitting the uplink modulated light through the a second optical coupler. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic of a TORminator system, in accordance with some embodiments. 
         FIG. 2A  shows an example schematic of a TORminator module, in accordance with some embodiments. 
         FIG. 2B  shows an example architectural diagram of a laser chip, in accordance with some embodiments of the present invention. 
         FIG. 2C  shows an example architectural diagram of a TeraPHY chip, in accordance with some embodiments. 
         FIG. 2D  shows an example schematic diagram of a TeraPHY chip, in accordance with some embodiments. 
         FIG. 2E  shows an example schematic diagram of chip-to-chip optical data communication, in accordance with some embodiments. 
         FIG. 2F  shows an example transceiver macro implemented within the TeraPHY chip, in accordance with some embodiments. 
         FIG. 3  shows a schematic of one SmartDistribuTOR module with an example downlink fiber wavelength plan for the downlink optical fiber and an example uplink fiber wavelength plan for the uplink optical fiber, in accordance with some embodiments. 
         FIG. 4  shows a schematic of the tunable optical DEMUX block within the SmartDistribuTOR module, in accordance with some embodiments. 
         FIG. 5  shows a schematic of the tunable optical MUX block within the SmartDistribuTOR module, in accordance with some embodiments. 
         FIG. 6  shows a schematic of a server-side electro-optical module (“Reverb module”) within a server, in accordance with some embodiments. 
         FIG. 7  shows a schematic of the Reverb chip, in accordance with some embodiments. 
         FIG. 8  shows an example uplink and downlink wavelength plan per downlink optical fiber and uplink optical fiber, in accordance with some embodiments. 
         FIG. 9  shows the TORminator system implemented across multiple racks within a datacenter, in accordance with some embodiments. 
         FIG. 10  shows a flowchart of a method for controlling data communication, in accordance with some embodiments. 
         FIG. 11  shows a flowchart of a method for operating an optical multiplexer/demultiplexer module, in accordance with some embodiments. 
         FIG. 12  shows a flowchart of a method for operating an electro-optical interface of a server, in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention. 
     In current data-centers, servers are organized in racks. Each rack includes a Top-of-Rack (TOR) switch, which connects the servers in the rack to the rest of the data-center network (typically called the core or the spine). Since the throughput of the switches increases faster than the throughput needs of each individual server in the rack, there exists an opportunity for a single switch to feed more than one rack, thereby eliminating a stage in the network hierarchy and providing significant latency and cost savings. This network architecture is known as End-of-Row (EOR) or Middle-of-Row (MOR), depending on the location of the switch within a row of racks. Specifically, EOR architecture has the switch located in the rack at the end of the row, and MOR architecture has the switch located in the rack at the middle of the row. In current data-centers, TOR architecture (in which a switch is located at the top of each rack) is preferred since rack-to-spine links are optical, while the dense server-to-TOR switch links are electrical, which minimizes the cabling costs. 
     Systems and methods are disclosed herein that utilize highly integrated electronic-photonic transceiver technology to provide a new EOR/MOR architecture in which photonic interconnects connect the servers in various racks to the EOR/MOR switch, enabling row connectivity capability that overcomes the length limitations of traditional copper cabling. This new EOR/MOR architecture is referred to as a “TORminator system”  100 . 
       FIG. 1  shows a schematic of the TORminator system  100 , in accordance with some embodiments.  FIG. 1  shows the connectivity within the TORminator system  100  between one EOR/MOR switch linecard  101  and a number (M) of servers. In the example of  FIG. 1 , M equals 128, such that the one EOR/MOR switch linecard  101  and the TORminator system  100  services 128 servers. In some embodiments, the M servers are distributed across multiple racks. In some embodiments, each rack includes a number (N) of servers. In the example of  FIG. 1 , N equals 8, with each rack including 8 servers. 
     A rack switch  103  in the linecard  101  is connected electrically to a TORminator module  107  on the linecard  101  through an electrical bus  105 . In some embodiments, the electrical bus  105  is a 128 data communication lane, Pulse-Amplitude Modulation 4-Level (PAM4), Very Short Reach (VSR) bus operating at 100 gigabits per second per lane (Gbps/lane). In some embodiments, each data communication lane of the electrical bus  105  is a full-duplex differential signaling lane that includes one pair of conductors for transmitting data and one pair of conductors for receiving data. However, it should be understood that in other embodiments, alternative data communication lane configurations can be implemented. It should also be understood that in other embodiments, the electrical bus  105  can be configured to have more or less than 128 data communication lanes and can operate at either higher data rates or lower data rates than 100 Gbps/lane. In some embodiments, each data communication lane in the electrical bus  105  is designated to service a different server in the datacenter. Therefore, in some embodiments, the TORminator system  100  is configured to connect with 128 servers, and the electrical bus  105  is configured to include 128 data communication lanes. 
     The TORminator module  107  is configured and connected to convert the data from the electrical domain of the rack switch  103  to the optical domain that exists between the TORminator module  107  and the servers. The TORminator module  107  is configured to send data in the optical domain to a number (K) of SmartDistribuTOR modules  111 - 1  through  111 -K. In the example of  FIG. 1 , K equals 16, such that the TORminator module  107  is configured to send data in the optical domain to 16 SmartDistribuTOR modules  111 - 1  through  111 - 16 . It should be understood, however, that in other embodiments the number K of SmartDistribuTOR modules  111 - 1  through  111 -K that are connected to a given TORminator module  107  can be either less than or greater than 16. The TORminator module  107  includes K duplex optical ports  109 - 1  through  109 -K. Each optical port  109 - 1  through  109 -K provides for optical coupling to a respective downlink optical fiber d 1  through dK, and for optical coupling to a respective uplink optical fiber u 1  through uK. In the example of  FIG. 1 , because K is 16, there are 16 optical ports  109 - 1  through  109 - 16  that respectively provide for optical coupling to downlink optical fibers d 1  through d 16 , and that respectively provide for optical coupling to uplink optical fibers u 1  through u 16 . 
     Each pair of downlink optical fibers d 1  through dK and uplink optical fibers u 1  through uK is connected to a respective one of the SmartDistribuTOR modules  111 - 1  through  111 -K. For example, in  FIG. 1 , the pair of downlink optical fiber d 1  and uplink optical fiber u 1  is connected to the SmartDistribuTOR modules  111 - 1 . Similarly, the pair of downlink optical fiber d 16  and uplink optical fiber u 16  is connected to the SmartDistribuTOR modules  111 - 16 . Each of the SmartDistribuTOR modules  111 - 1  through  111 -K has a duplex optical port  113  to which the corresponding downlink optical fiber d 1  through dK and corresponding uplink optical fiber u 1  through uK are connected. 
     In some embodiments, each of the SmartDistribuTOR modules  111 - 1  through  111 -K is installed in a corresponding rack, e.g., at the top of a corresponding rack. Generally speaking, the SmartDistribuTOR module  111 - 1  through  111 -K splits multiple optical channels from the corresponding downlink optical fiber d 1  through dK, and respectively directs the multiple optical channels to multiple servers in the rack in which the SmartDistribuTOR module is located. Each optical channel includes at least one modulated laser light wavelength and at least one continuous wave (unmodulated) laser light wavelength. 
       FIG. 1  shows a schematic of the SmartDistribuTOR module  111 - 1  through  111 -K with an example uplink and downlink wavelength plan per uplink and downlink optical fiber, in accordance with some embodiments. In some embodiments, dense wavelength division multiplexing (DWDM) can be used to pack a large number of optical channels and increase the number of servers reachable via a single uplink and downlink optical fiber pair. Each SmartDistribuTOR module  111 - 1  through  111 -K includes a downlink optical waveguide  115  optically coupled through the optical port  113  to the corresponding downlink optical fiber d 1  through dK. The downlink optical waveguide  115  is optically connected to an optical demultiplexer  119  that is configured to separate N downlink data communication optical signals received through the downlink optical waveguide  115  based on optical wavelength. The optical demultiplexer  119  is also configured to respectively direct the N downlink data communication optical signals to N server downlink optical ports S 1   d  through SNd. 
     For example,  FIG. 1  shows eight optical channels Ch 1  through Ch 8  transmitted through the downlink optical waveguide  115 , with one modulated wavelength per optical channel Ch 1  through Ch 8 , and with one unmodulated continuous wave wavelength per optical channel Ch 1  through Ch 8 . Specifically, optical channel Ch 1  includes one unmodulated continuous wave wavelength designated as signal  1 , and one modulated wavelength designated as signal  2 . Optical channel Ch 2  includes one unmodulated continuous wave wavelength designated as signal  3 , and one modulated wavelength designated as signal  4 . Optical channel Ch 3  includes one unmodulated continuous wave wavelength designated as signal  5 , and one modulated wavelength designated as signal  6 . Optical channel Ch 4  includes one unmodulated continuous wave wavelength designated as signal  7 , and one modulated wavelength designated as signal  8 . Optical channel Ch 5  includes one unmodulated continuous wave wavelength designated as signal  9 , and one modulated wavelength designated as signal  10 . Optical channel Ch 6  includes one unmodulated continuous wave wavelength designated as signal  11 , and one modulated wavelength designated as signal  12 . Optical channel Ch 7  includes one unmodulated continuous wave wavelength designated as signal  13 , and one modulated wavelength designated as signal  14 . Optical channel Ch 8  includes one unmodulated continuous wave wavelength designated as signal  15 , and one modulated wavelength designated as signal  16 . In some embodiments, each modulated wavelength can carry 100 gigabits per second (Gbps) of data, by way of example. In some embodiments, each modulated wavelength can carry either more than or less than 100 Gbps of data. 
     In the example of  FIG. 1 , the optical demultiplexer  119  is configured to separate eight downlink data communication optical signals (signals  2 ,  4 ,  6 ,  8 ,  10 ,  12 ,  14 , and  16 ) received through the downlink optical waveguide  115  based on optical wavelength. The optical demultiplexer  119  is also configured to respectively direct the eight downlink data communication optical signals (signals  2 ,  4 ,  6 ,  8 ,  10 ,  12 ,  14 , and  16 ) through eight respective optical waveguides  123  to eight server downlink optical ports S 1   d  through S 8   d . The optical demultiplexer  119  is also configured to separate eight unmodulated continuous wave optical signals (signals  1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 , and  15 ) received through the downlink optical waveguide  115  based on optical wavelength. The optical demultiplexer  119  is also configured to respectively direct the eight unmodulated continuous wave optical signals (signals  1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 , and  15 ) through the eight respective optical waveguides  123  to the eight server downlink optical ports S 1   d  through S 8   d . Therefore, each server downlink optical port S 1   d  through S 8   d  transmits one downlink data communication optical signal and one unmodulated continuous wave optical signal to a corresponding server. 
     For example, both the unmodulated continuous wave optical signal  1  and the downlink data communication optical signal  2  that constitute channel Ch 1  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 1   d  and through an optical fiber d 11  to the server  1 . Both the unmodulated continuous wave optical signal  3  and the downlink data communication optical signal  4  that constitute channel Ch 2  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 2   d  and through an optical fiber d 12  to the server  2 . Both the unmodulated continuous wave optical signal  5  and the downlink data communication optical signal  6  that constitute channel Ch 3  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 3   d  and through an optical fiber d 13  to the server  3 . Both the unmodulated continuous wave optical signal  7  and the downlink data communication optical signal  8  that constitute channel Ch 4  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 4   d  and through an optical fiber d 14  to the server  4 . Both the unmodulated continuous wave optical signal  9  and the downlink data communication optical signal  10  that constitute channel Ch 5  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 5   d  and through an optical fiber d 15  to the server  5 . Both the unmodulated continuous wave optical signal  11  and the downlink data communication optical signal  12  that constitute channel Ch 6  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 6   d  and through an optical fiber d 16  to the server  6 . Both the unmodulated continuous wave optical signal  13  and the downlink data communication optical signal  14  that constitute channel Ch 7  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 7   d  and through an optical fiber d 17  to the server  7 . Both the unmodulated continuous wave optical signal  15  and the downlink data communication optical signal  16  that constitute channel Ch 8  are transmitted through one of the optical waveguides  123  to the server downlink optical port S 8   d  and through an optical fiber d 18  to the server  8 . 
     Each SmartDistribuTOR module  111 - 1  through  111 -K also includes an uplink optical waveguide  117  optically coupled through the optical port  113  to the corresponding uplink optical fiber u 1  through uK. The uplink optical waveguide  117  is connected to the optical output of an optical multiplexer  121 . The optical multiplexer  121  is configured to aggregate N uplink data communication optical signals received through the N server uplink optical ports S 1   u  through SNu onto the single optical waveguide  117  optically coupled to the optical port  113 . The example of  FIG. 1  shows eight optical channels Ch 1  through Ch 8  on the uplink optical waveguide  117 , with one modulated wavelength per optical channel Ch 1  through Ch 8 . 
     In the example of  FIG. 1 , the SmartDistribuTOR module  111 - 1  includes eight server uplink optical ports S 1   u  through S 8   u . The server uplink optical port S 1   u  is connected to an uplink optical fiber u 11  through which an uplink data communication optical signal  1  is transmitted. The server uplink optical port S 1   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . The server uplink optical port S 2   u  is connected to an uplink optical fiber u 12  through which an uplink data communication optical signal  3  is transmitted. The server uplink optical port S 2   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . The server uplink optical port S 3   u  is connected to an uplink optical fiber u 13  through which an uplink data communication optical signal  5  is transmitted. The server uplink optical port S 3   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . The server uplink optical port S 4   u  is connected to an uplink optical fiber u 14  through which an uplink data communication optical signal  7  is transmitted. The server uplink optical port S 4   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . The server uplink optical port S 5   u  is connected to an uplink optical fiber u 15  through which an uplink data communication optical signal  9  is transmitted. The server uplink optical port S 5   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . The server uplink optical port S 6   u  is connected to an uplink optical fiber u 16  through which an uplink data communication optical signal  11  is transmitted. The server uplink optical port S 6   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . The server uplink optical port S 7   u  is connected to an uplink optical fiber u 17  through which an uplink data communication optical signal  13  is transmitted. The server uplink optical port S 7   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . The server uplink optical port S 8   u  is connected to an uplink optical fiber u 18  through which an uplink data communication optical signal  15  is transmitted. The server uplink optical port S 8   u  is optically connected through a corresponding one of optical waveguides  125  to the optical multiplexer  121 . 
     The uplink data communication optical signal  1  constitutes uplink channel Ch 1 . The uplink data communication optical signal  3  constitutes uplink channel Ch 2 . The uplink data communication optical signal  5  constitutes uplink channel Ch 3 . The uplink data communication optical signal  7  constitutes uplink channel Ch 4 . The uplink data communication optical signal  9  constitutes uplink channel Ch 5 . The uplink data communication optical signal  11  constitutes uplink channel Ch 6 . The uplink data communication optical signal  13  constitutes uplink channel Ch 7 . The uplink data communication optical signal  15  constitutes uplink channel Ch 8 . In some embodiments, each modulated wavelength corresponding to uplink data communication optical signals  1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 , and  15  can carry 100 Gbps of data, by way of example. In some embodiments, each modulated wavelength corresponding to uplink data communication optical signals  1 ,  3 ,  5 ,  7 ,  9 ,  11 ,  13 , and  15  can carry either more than or less than 100 Gbps of data. 
     As shown in  FIG. 1 , an electro-optical module Rvb- 1  through Rvb-M (“Reverb”) is provided at each of servers  1  through M, respectively. Generally speaking, each electro-optical module Rvb- 1  through Rvb-M receives at least one optical channel and converts the modulated optical wavelength on the received optical channel to an electrical data-stream which is then forwarded to a network interface of the corresponding server as downlink traffic. Also, the electro-optical module Rvb- 1  through Rvb-M at each of servers  1  through M, respectively, modulates the continuous wave laser light wavelength with data provided by the network interface of the corresponding server for uplink connection to the rack switch  103  in the EOR/MOR switch linecard  101 . 
     On the uplink connection path, modulated optical wavelengths from several of the electro-optical modules Rvb- 1  through Rvb-M of several corresponding servers  1  through M are multiplexed together by the optical multiplexer  121  within the SmartDistribuTOR module  111 - 1  through  111 -K onto corresponding optical fibers u 1  through uK connecting the SmartDistribuTOR module  111 - 1  through  111 -K with the TORminator module  107  on the EOR/MOR switch linecard  101 . For example,  FIG. 1  shows that modulated optical wavelengths from electro-optical modules Rvb- 1  through Rvb- 8  of corresponding servers  1  through  8  are multiplexed together by the optical multiplexer  121  within the SmartDistribuTOR module  111 - 1  onto the uplink optical waveguide  117  for transmission over the optical fiber u 1  that connects the SmartDistribuTOR module  111 - 1  with the TORminator module  107  on the EOR/MOR switch linecard  101 . Similarly,  FIG. 1  shows that modulated optical wavelengths from electro-optical modules Rvb- 121  through Rvb- 128  of corresponding servers  121  through  128  are multiplexed together by the optical multiplexer  121  within the SmartDistribuTOR module  111 - 16  onto the uplink optical waveguide  117  for transmission over the optical fiber u 16  that connects the SmartDistribuTOR module  111 - 16  with the TORminator module  107  on the EOR/MOR switch linecard  101 . The TORminator module  107  converts multiple modulated optical wavelengths from multiple optical fibers into a multiple corresponding electrical data streams that are forwarded to the rack switch  103  on the linecard  101  as uplink data traffic. 
       FIG. 2A  shows an example schematic of the TORminator module  107 , in accordance with some embodiments. The TORminator module  107  includes a multi-port, multi-wavelength-per-port laser supply chip  205  (e.g., SuperNova laser chip by Ayar Labs, Inc.) that provides multiple wavelengths of laser light to a TeraPHY chip  203 , as indicated by optical connection  213 . The TeraPHY chip  203  within the TORminator module  107  receives the electrical downlink data stream from the rack switch  103 , via an optional serializer/deserializer (SerDes) chip  201 , as indicated by electrical connection  211 . The TeraPHY chip  203  modulates the wavelengths of laser light provided by the laser supply chip  205  with the electrical downlink data stream. In some embodiments, the optical signals from the TeraPHY chip  203  go directly to the SmartDistribuTOR modules  111 - 1  through  111 -K through the optical ports  109 - 1  through  109 -K and corresponding optical fibers d 1  through dK. In some embodiments, the optical signals from the TeraPHY chip  203  are transmitted through optical connection  217  to a downlink semiconductor optical amplifier (SOA) array chip  207  (e.g., Arc SOA chip) that operates to amplify the optical signals before the optical signals are transmitted from the TORminator module  107  to the SmartDistribuTOR modules  111 - 1  through  111 -K.  FIG. 2A  shows a collection of optical waveguides  221  configured to convey the optical signals form the SOA chip  207  to the respective optical ports  109 - 1  through  109 -K. 
     In some embodiments, the optical uplink signals received by the TORminator module  107  from the SmartDistribuTOR modules  111 - 1  through  111 -K are coupled directly to the TeraPHY chip  203 . The TeraPHY chip  203  functions to convert the received optical uplink signals to electrical data streams and forward the electrical data streams to the rack switch  103 . In some embodiments, the electrical data streams are processed by the SerDes chip  201  in route to the rack switch  103 . In some embodiments, the optical uplink signals received by the TORminator module  107  from the SmartDistribuTOR modules  111 - 1  through  111 -K are first coupled into an SOA array chip  209  (e.g., Arc SOA chip) for amplification.  FIG. 2A  shows a collection of optical waveguides  219  configured to convey the optical signals form the respective optical ports  109 - 1  through  109 -K to the SOA chip  209 . Then, the amplified optical uplink signals are coupled/transmitted from the SOA array chip  209  through optical connection  215  into the TeraPHY chip  203 . 
     In some embodiments, the TeraPHY chip  203  includes silicon-photonic components driven by the SerDes chip  201 . In some embodiments, the TeraPHY chip  203  includes silicon-photonic components and electronic transceiver circuitry monolithically integrated on the same die. In some embodiments, the laser chip  205  is implemented in an Indium Phosphide (InP) process. In some embodiments, the SOA array chip  207  is implemented in an InP process capable of handling both polarizations of light. And, in some embodiments, the SOA array chip  209  is implemented in an InP process capable of handling both polarizations of light. 
     In some embodiments, the TORminator module  107  is an edge-pluggable module having the laser chip  205 , the SerDes chip  201 , the TeraPHY chip  203 , and the SOA array chips  207 ,  209  packaged on a printed circuit board (PCB) of the TORminator module  107 . In these embodiments, the TORminator module  107  can be connected to the edge-style pluggable connector mounted on the EOR/MOR switch linecard  101 . In some embodiments, the TORminator module  107  is connected to the EOR/MOR switch linecard  101  using a mezzanine connector. In some embodiments, the TeraPHY chip  203 , the laser chip  205 , and the SOA array chips  207 ,  209  are socketed to the EOR/MOR switch linecard  101 . In some embodiments, the TeraPHY chip  203  is co-packaged with the rack switch  103 , while the laser chip  205  and the SOA array chips  207 ,  209  are mounted separately to the EOR/MOR switch linecard  101 . 
     In some embodiments, the multiple wavelengths (e.g., 16 wavelengths) of laser light provided by the laser chip  205  are coupled to one or more optical transceiver macros on the TeraPHY chip  203 . Each optical transceiver macro on the TeraPHY chip  203  includes a transmit macro and a receive macro. Each of the transmit and receive macros includes slices (one slice per wavelength). The transmit macro includes a common optical waveguide and a number of ring modulators (one per slice) coupled into the common optical waveguide, where each ring modulator is centered to modulate one of the incoming wavelengths from the laser chip  205 . In some embodiments, the ring modulators in the transmit macro are configured according to the channelized wavelength plan as shown in the SmartDistribuTOR modules  111 - 1  through  111 -K of  FIG. 1 , such that some of the wavelengths are modulated for downlink traffic and some of the wavelengths are left unmodulated to be forwarded to the servers  1  through N connected to the corresponding SmartDistribuTOR module to provide for modulation of uplink data communication traffic. In some embodiments, the ring modulators in each slice are driven by the electrical circuits in that slice on the same TeraPHY chip  203 . Or, in some embodiments, the ring modulators in each slice are driven by the electrical circuits on a separate die. In the receiver macro, a ring-resonator filter in each slice drops a corresponding wavelength from the common optical waveguide. This corresponding wavelength is then converted into an electrical signal by a photodetector embedded in that slice. In some embodiments, the photodetector and the ring filter are combined into a single structure. In some embodiments, the electrical signal from the photodetector is further amplified by the receiver circuits on the same TeraPHY chip  203  and forwarded to the rack switch  103 . In some embodiments, the TeraPHY chip  203  includes only optical components, and the associated electrical circuit components are located on a separate chip. In some embodiments, the electrical link between the rack switch  103  and the electro-optical components in the TeraPHY chip  203  is retimed. However, in some embodiments, the electrical link between the rack switch  103  and the electro-optical components in the TeraPHY chip  203  is not retimed. 
     The laser chip  205  is designed and configured to supply laser light having one or more wavelengths. It should be understood that the term “wavelength” as used herein refers to the wavelength of electromagnetic radiation. And, the term “light” as used herein refers to electromagnetic radiation within a portion of the electromagnetic spectrum that is usable by optical data communication systems. In some embodiments, the portion of the electromagnetic spectrum includes light having wavelengths within a range extending from about 1100 nanometers to about 1565 nanometers (covering from the O-Band to the C-Band, inclusively, of the electromagnetic spectrum). However, it should be understood that the portion of the electromagnetic spectrum as referred to herein can include light having wavelengths either less than 1100 nanometers or greater than 1565 nanometers, so long as the light is usable by an optical data communication system for encoding, transmission, and decoding of digital data through modulation/de-modulation of the light. In some embodiments, the light used in optical data communication systems has wavelengths in the near-infrared portion of the electromagnetic spectrum. Also, the term “laser beam” as used herein refers to a beam of light generated by a laser device. It should be understood that a laser beam may be confined to propagate in an optical waveguide, such as (but not limited to) an optical fiber or an optical waveguide within a planar lightwave circuit (PLC). In some embodiments, the laser beam is polarized. And, in some embodiments, the light of a given laser beam has a single wavelength, where the single wavelength can refer to either essentially one wavelength or can refer to a narrow band of wavelengths that can be identified and processed by an optical data communication system as if it were a single wavelength. 
       FIG. 2B  shows an example architectural diagram of the laser chip  205 , in accordance with some embodiments of the present invention. The laser chip  205  includes a laser source  231  and an optical marshalling module  233 . The laser source  231  is configured to generate and output a plurality of laser beams, i.e., (X) laser beams. The plurality of laser beams have different wavelengths (λ 1 -λ X ) relative to each other, where the different wavelengths (λ 1 -λ X ) are distinguishable to an optical data communication system. In some embodiments, the laser source  231  includes a plurality of lasers  235 - 1  to  235 -X for respectively generating the plurality (X) of laser beams, where each laser  235 - 1  to  235 -X generates and outputs a laser beam at a respective one of the different wavelengths (λ 1 -λ X ). Each laser beam generated by the plurality of lasers  235 - 1  to  235 -X is provided to a respective optical output port  237 - 1  to  237 -X of the laser source  231  for transmission from the laser source  231 . In some embodiments, each of the plurality of lasers  235 - 1  to  235 -X is a distributed feedback laser configured to generate laser light at a particular one of the different wavelengths (λ 1 -λ X ). In some embodiments, the laser source  231  can be defined as a separate component, such as a separate chip. However, in other embodiments, the laser source  231  can be integrated within a planar lightwave circuit (PLC) on a chip that includes other components in addition to the laser source  231 . 
     In the example embodiment of  FIG. 2B , the laser source  231  is defined as a separate component attached to a substrate  230 , such as an electronic packaging substrate. In various embodiments, the substrate  230  can be an organic substrate or a ceramic substrate, or essentially any other type of substrate upon which electronic devices and/or optical-electronic devices and/or optical waveguides and/or optical fiber(s)/fiber ribbon(s) can be mounted. For example, in some embodiments, the substrate  230  can be an Indium-Phosphide (III-V) substrate. Or, in another example, the substrate  230  can be an Al 2 O 3  substrate. It should be understood that in various embodiments the laser source  231  can be attached/mounted to the substrate  230  using essentially any known electronic packaging process, such as flip-chip bonding, which can optionally include disposition of a ball grid array (BGA), bumps, solder, under-fill, and/or other component(s), between the laser source  231  and the substrate  230 , and include bonding techniques such as mass reflow, thermal-compression bonding (TCB), or essentially any other suitable bonding technique. 
     The optical marshalling module  233  is configured to receive the plurality of laser beams of the different wavelengths (λ 1 -λ X ) from the laser source  231  at a corresponding plurality of optical input ports  239 - 1  to  239 -X of the optical marshalling module  233 . The optical marshalling module  233  is also configured to distribute a portion of each of the plurality of laser beams to each of a plurality of optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233 , where (Y) is the number of optical output ports of the optical marshalling module  233 . The optical marshalling module  233  operates to distribute the plurality of laser beams such that all of the different wavelengths (λ 1 -λ X ) of the plurality of laser beams are provided to each of the plurality of optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233 . Therefore, it should be understood that the optical marshalling module  233  operates to provide light at all of the different wavelengths (λ 1 -λ X ) of the plurality of laser beams to each one of the optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233 , as indicated in  FIG. 2B . In this manner, for the laser chip  205 , each one of the optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233  provides a corresponding one of a plurality of multi-wavelength laser outputs MWL- 1  to MWL-Y. 
     In some embodiments, the optical marshalling module  233  is configured to maintain a polarization of each of the plurality of laser beams between the plurality of optical input ports  239 - 1  to  239 -X of the optical marshalling module  233  and the plurality of optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233 . Also, in some embodiments, the optical marshalling module  233  is configured such that each of the plurality of optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233  receives a similar amount of optical power of any given one of the plurality of laser beams within a factor of five. In other words, in some embodiments, the amount of light of a given wavelength, i.e., one of the different wavelengths (λ 1 -λ X ), that is provided by the optical marshalling module  233  to a particular one of the optical output ports  241 - 1  to  241 -Y is the same within a factor of five to the amount of light of the given wavelength that is provided by the optical marshalling module  233  to others of the optical output ports  241 - 1  to  241 -Y. It should be understood that the factor of five mentioned above is an example embodiment. In other embodiments, the factor of five mentioned above can be changed to a factor of another value, such as to a factor of two, or three, or four, or six, etc., or to any other value in between or less than or greater than. The point to be understood is that the optical marshalling module  233  can be configured to control the amount of light of a given wavelength that is provided to each of the optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233 , and in turn can be configured to control a uniformity of the amount of light of a given wavelength provided to each of the optical output ports  241 - 1  to  241 -Y of the optical marshalling module  233 . 
     In the example embodiment, of  FIG. 2B , the optical marshalling module  233  is defined as a separate component attached to the substrate  230 . Therefore, it should be understood that in the example embodiment of the laser chip  205 , the laser source  231  and the optical marshalling module  233  are physically separate components. It should be understood that in various embodiments the optical marshalling module  233  can be attached/mounted to the substrate  230  using essentially any known electronic packaging process. Also, in some embodiments, the optical marshalling module  233  is configured as a non-electrical component, i.e., as a passive component, and can be attached/mounted to the substrate  230  using techniques that do not involve establishment of electrical connections between the optical marshalling module  233  and the substrate  230 , such as by use of an epoxy or other type of adhesive material. In some embodiments, rather than being defined as a separate component, the optical marshalling module  233  can be integrated within a PLC on a chip that includes other components in addition to the optical marshalling module  233 . In some embodiments, both the optical marshalling module  233  and the laser source  231  are implemented together within a same PLC. 
     In some embodiments, the laser source  231  is aligned with the optical marshalling module  233  to direct the plurality of laser beams transmitted from the optical outputs  237 - 1  to  237 -X of the laser source  231  into respective ones of the optical input ports  239 - 1  to  239 -X of the optical marshalling module  233 . In some embodiments, the optical marshalling module  233  is positioned spaced apart from the laser source  231 . In some embodiments, the optical marshalling module  233  is positioned in contact with the laser source  231 . And, in some embodiments, a portion of the optical marshalling module  233  is positioned to overlap a portion of the laser source  231 . In the example embodiment of the laser chip  205  as shown in  FIG. 2B , the optical marshalling module  233  is positioned spaced apart from the laser source  231 , and an optical waveguide  243  is positioned between the laser source  231  and the optical marshalling module  233 . The optical waveguide  243  is configured to direct the plurality of laser beams from the laser source  231  into respective ones of the plurality of optical input ports  239 - 1  to  239 -X of the optical marshalling module  233 , as indicated by lines  245 - 1  to  245 -X. 
     In various embodiments, the optical waveguide  243  can be formed of essentially any material through which light can be channeled from an entry location on the optical waveguide  243  to an exit location on the optical waveguide  243 . For example, in various embodiments, the optical waveguide  243  can be formed of glass, SiN, SiO2, germanium-oxide, and/or silica, among other materials. In some embodiments, the optical waveguide  243  is configured to maintain a polarization of the plurality of laser beams between the laser source  231  and the optical marshalling module  233 . In some embodiments, the optical waveguide  243  includes (X) optical conveyance channels, where each optical conveyance channel extends from a respective one of the optical output ports  237 - 1  to  237 -X of the laser source  231  to a respective one of the optical input ports  239 - 1  to  239 -X of the optical marshalling module  233 . In some embodiments, each of the (X) optical conveyance channels of the optical waveguide  243  has a substantially rectangular cross-section in a plane normal to a direction of propagation of the laser beam, i.e., normal to the x-direction as shown in  FIG. 2B , which serves to maintain a polarization of the laser beam as it propagates from the laser source  231  to the optical marshalling module  233 . 
     In the example embodiment of  FIG. 2B , the optical waveguide  243  is defined as a separate component attached to the substrate  230 . Therefore, it should be understood that in the example embodiment of the laser chip  205 , the laser source  231 , the optical waveguide  243 , and the optical marshalling module  233  are physically separate components. It should be understood that in various embodiments the optical waveguide  243  can be attached/mounted to the substrate  230  using essentially any known electronic packaging process. Also, in some embodiments, the optical waveguide  243  is configured as a non-electrical component, i.e., as a passive component, and can be attached/mounted to the substrate  230  using techniques that do not involve establishment of electrical connections between the optical waveguide  243  and the substrate  230 , such as by use of an epoxy or other type of adhesive material. In some embodiments, rather than being defined as a separate component, the optical waveguide  243  can be integrated within a PLC on a chip that includes other components in addition to the optical waveguide  243 . In some embodiments, laser source  231 , the optical waveguide  243 , and the optical marshalling module  233  are implemented together within a same PLC. 
     In some embodiments, the laser chip  205  includes a thermal spreader component disposed proximate to the laser source  231 . The thermal spreader component is configured to spread a thermal output of the plurality of lasers  235 - 1  to  235 -X to provide substantial uniformity in temperature-dependent wavelength drift among the plurality of lasers  235 - 1  to  235 -X. In some embodiments, the thermal spreader component is included within the laser source  231 . In some embodiments, the thermal spreader component is included within the substrate  230 . In some embodiments, the thermal spreader component is defined separate from each of the laser source  231 , the optical marshalling module  233 , and the substrate  230 . In some embodiments, the thermal spreader component is included within the optical marshalling module  233 , with the thermal spreader component portion of the optical marshalling module  233  physically overlapping the laser source  231 . In some embodiments, the thermal spreader component is included within the optical waveguide  243 , with the thermal spreader component portion of the optical waveguide  243  physically overlapping the laser source  231 . In various embodiments, the thermal spreader component is formed of a thermally conductive material, such as a metallic material by way of example. In some embodiments, the thermal spreader component can incorporate an element configured to actively transfer heat away from the plurality of lasers  235 - 1  to  235 -X, such as a thermoelectric cooler by way of example. Also, in some embodiments, the thermal spreader component is formed to have a sufficient bulk mass so as to function as a heat sink for heat emanating from the plurality of lasers  235 - 1  to  235 -X of the laser source  231 . Additional description of various embodiments of the laser chip  205  is provided in U.S. patent application Ser. No. 15/650,586, which is incorporated in its entirety herein by reference, and in U.S. patent application Ser. No. 16/194,250, which is incorporated in its entirety herein by reference. 
       FIG. 2C  shows an example architectural diagram of the TeraPHY chip  203 , in accordance with some embodiments. In the example of  FIG. 2C , the TeraPHY chip  203  includes processor and memory transceiver banks  251 , a processor  253 , a memory bank  255 , and independent transceiver test sites  257 .  FIG. 2C  also shows an enlarged view of an example transmitter bank  251 A that is formed within the processor and memory transceiver banks  251 . The example transmitter bank  251 A includes a optical input  259  for receiving laser light from the laser chip  205 . In some embodiments, the optical input  259  is an optical grating coupler. The transmitter bank  251 A also includes an optical waveguide  261  that extends from the optical input  259  to an optical output  263  of the transmitter bank  251 A. In some embodiments, the optical output  263  is an optical grating coupler. The optical waveguide  261  passes through a series of optical transmitters formed within the transmitter bank  251 A. The example transmitter bank  251 A includes eleven optical transmitters. 
       FIG. 2C  shows an enlarged view of an example optical transmitter  265 . Within the optical transmitter  265 , the optical waveguide  261  passes by/around a ring resonator of microring modulator  267 . Light modulation provided by the microring modulator  267  is controlled by a modulator driver circuit  269 . The modulator driver circuit  269  controls the microring modulator  267  to generate modulated laser light that corresponds to an imprinting of an electrical data communication stream onto continuous wave laser light. The modulated laser light exits the microring modulator  267  through the optical waveguide  261  and continues on to the optical output  263  of the transmitter bank  251 A. The optical transmitter  265  also includes a tuning controller circuit  271  configured and connected to control a temperature of the microring modulator  267  in order to operate the microring modulator  267  at a specific resonant wavelength. In this manner, the modulated laser light generated by the microring modulator  267  is at the specific resonant wavelength. The optical transmitter  265  also includes backend digital circuitry  273  to support operation of the various electrical components within the optical transmitter  265 . The optical transmitter  265  also includes a drop port photodetector  275  that is optically coupled to the microring modulator  267  to provide for detection and measurement of wavelength-specific light absorption within the ring resonator of the microring modulator  267 . 
       FIG. 2C  also shows an enlarged view of an example optical receiver bank  251 B that is formed within the processor and memory transceiver banks  251 . The optical receiver bank  251 B includes multiple optical receivers, each configured and connected to receive modulated laser light and demodulate the received modulated laser light to generate a corresponding digital data communication stream.  FIG. 2C  shows an enlarged view of one of the optical receivers  276 . The optical receiver  276  includes an optical input  277  for receiving modulated laser light. In some embodiments, the optical input  277  is an optical grating coupler. The optical input  277  is connected through a corresponding optical waveguide  279  to a photodetector  281 . The photodetector  281  is controlled and operated to provide wavelength-specific detection of light coming in through the optical waveguide  279 . The optical receiver  276  also includes a receiver circuit  283  configured and connected to generate a digital data communication stream that corresponds to the incoming stream of modulated light as detected by the photodetector  281 . The optical receiver  276  also includes backend digital circuitry  285  to support operation of the various electrical components within the optical receiver  276 . In the example of  FIG. 2C , the optical receiver bank  251 B includes eleven separate optical receivers  276 . In some embodiments, the TeraPHY chip  203  can be configured as described in Sun, Chen, et al. “Single-chip microprocessor that communicates directly using light.”  Nature  528.7583 (2015): 534, which is incorporated in its entirety herein by reference for all purposes. 
       FIG. 2D  shows an example schematic diagram of the TeraPHY chip  203 , in accordance with some embodiments. The TeraPHY chip  203  includes an electrical PHY specification  286 . In some embodiments, the electrical PHY specification  286  is an Advance Interface Bus by Intel. In some embodiments, the electrical PHY specification  286  includes a High Bandwidth Memory (HBM) and Kandou Bus for serialization/deserialization of data. The electrical PHY specification  286  is interfaced with an optical PHY specification  287  through glue logic  289 . The optical PHY specification  287  includes a number of pairs of optical transmitters (Tx) and optical receivers (Rx). The glue logic  289  includes cross-bar switches and other circuitry as needed to interface the electrical PHY specification  286  with the optical PHY specification  287 . In some embodiments, the optical transmitters (Tx) and optical receivers (Rx) are combined in pairs, with each Tx/Rx pair forming an optical transceiver. The optical transmitters (Tx) and optical receivers (Rx) are optically connected to an optical fiber array  290 . The optical fiber array  290  provides for attachment of respective optical fibers to each of the optical transmitters (Tx) and optical receivers (Rx) in the optical PHY specification  287 . In various embodiments, the optical fibers can be optically connected to the optical transmitters (Tx) and optical receivers (Rx) through vertical optical grating couplers, edge optical couplers, or essentially any other type of optical coupling device. The TeraPHY chip  203  also includes management circuits  291  and general purpose input/output (GPIO) components  292  for communicating electrical data signals to and from the TeraPHY chip  203 . In various embodiments, the GPIO components  292  can include Serial Peripheral Interface (SPI) components and/or another type of component to enable off-chip data communication. It should be understood that the TeraPHY chip  203  can also include many other circuits, such as memory (e.g., SRAM), a CPU, analog circuits, or any other circuit that can be designed in CMOS. 
       FIG. 2E  shows an example schematic diagram of chip-to-chip optical data communication, in accordance with some embodiments.  FIG. 2E  shows an example optical transmitter bank  351  within a first chip (chip  1 ) operating to modulate five different wavelengths of continuous wave laser light to in turn generate five modulated light data streams, where each modulated light data stream corresponds to an input electrical data stream. In some embodiments, the example optical transmitter bank  351  represents components within the TeraPHY chip  203 . The optical transmitter bank  351  includes five ring resonators  353 ( 1 )- 353 ( 5 ) respectively controlled by five modulator drivers  355 ( 1 )- 355 ( 5 ). Each of the five ring resonators  353 ( 1 )- 353 ( 5 ) has a corresponding resistive thermal tuner (heater)  357 ( 1 )- 357 ( 5 ) that is controlled to operate the corresponding ring resonators  353 ( 1 )- 353 ( 5 ) at a prescribed optical wavelength. The thermal tuner  357 ( 1 ) controls the ring resonator  353 ( 1 ) to operate at the optical wavelength λ 1 . The thermal tuner  357 ( 2 ) controls the ring resonator  353 ( 2 ) to operate at the optical wavelength λ 2 . The thermal tuner  357 ( 3 ) controls the ring resonator  353 ( 3 ) to operate at the optical wavelength λ 3 . The thermal tuner  357 ( 4 ) controls the ring resonator  353 ( 4 ) to operate at the optical wavelength λ 4 . The thermal tuner  357 ( 5 ) controls the ring resonator  353 ( 5 ) to operate at the optical wavelength λ 5 . The thermal tuners  357 ( 1 )- 357 ( 5 ) are controlled by a ring tuning control circuit  358 . 
     Laser light that includes the five wavelengths λ 1  to λ 5  is transmitted from the laser chip  205  through the optical waveguide  213  to the optical port (optical grating coupler)  359  and through an optical waveguide  361 . The optical waveguide  361  extends past each of the ring resonators  353 ( 1 )- 353 ( 5 ). As the laser light travels through the optical waveguide  361  past a given ring resonators  353 ( 1 )- 353 ( 5 ), the wavelengths λ 1  to λ 5  of the laser light optically couple into the ring resonators  353 ( 1 )- 353 ( 5 ) based on the resonant wavelengths at which the ring resonators  353 ( 1 )- 353 ( 5 ) are operated. In this manner, wavelength λ 1  couples into ring resonator  353 ( 1 ). Wavelength λ 2  couples into ring resonator  353 ( 2 ). Wavelength λ 3  couples into ring resonator  353 ( 3 ). Wavelength λ 4  couples into ring resonator  353 ( 4 ). Wavelength λ 5  couples into ring resonator  353 ( 5 ). 
     The modulator driver  355 ( 1 ) receives an electrical data communication stream b 0  as an input. The modulator driver  355 ( 2 ) receives an electrical data communication stream b 1  as an input. The modulator driver  355 ( 3 ) receives an electrical data communication stream b 2  as an input. The modulator driver  355 ( 4 ) receives an electrical data communication stream b 3  as an input. The modulator driver  355 ( 5 ) receives an electrical data communication stream b 4  as an input. The modulator drivers  355 ( 1 )- 335 ( 5 ) operate to modulate the light coupled into the respective ring resonators  353 ( 1 )- 353 ( 5 ) to respectively generate modulated light streams representing the input electrical data communication streams b 0 -b 4 , respectively. The modulated light streams travel on through the optical waveguide  361  and through an optical output port  363  (optical grating coupler). The modulator drivers  355 ( 1 )- 335 ( 5 ) operate in accordance with clock signals generated by a clock distribution circuit  365 . 
     The five modulated light streams travel from the optical output port  363  through an optical waveguide  367  to a second chip (chip  2 ) in which an example optical receiver bank  369  operates to demodulate the five modulated light streams of different wavelengths λ 1  to λ 5  to in turn generate five electrical data communication streams that match the five electrical data communication streams b 0 -b 4 . The five modulated light streams travel from the optical waveguide  367  through an optical input port  371  (optical grating coupler) and into an optical waveguide  373 . 
     The optical receiver bank  369  includes five ring resonators  375 ( 1 )- 375 ( 5 ) respectively connected to five receiver circuits  377 ( 1 )- 377 ( 5 ). Each of the five ring resonators  375 ( 1 )- 375 ( 5 ) has a corresponding resistive thermal tuner (heater)  379 ( 1 )- 379 ( 5 ) that is controlled to operate the corresponding ring resonators  375 ( 1 )- 375 ( 5 ) at a prescribed optical wavelength. The thermal tuner  379 ( 1 ) controls the ring resonator  375 ( 1 ) to operate at the optical wavelength λ 1 . The thermal tuner  379 ( 2 ) controls the ring resonator  375 ( 2 ) to operate at the optical wavelength λ 2 . The thermal tuner  379 ( 3 ) controls the ring resonator  375 ( 3 ) to operate at the optical wavelength λ 3 . The thermal tuner  379 ( 4 ) controls the ring resonator  375 ( 4 ) to operate at the optical wavelength λ 4 . The thermal tuner  379 ( 5 ) controls the ring resonator  375 ( 5 ) to operate at the optical wavelength λ 5 . The thermal tuners  379 ( 1 )- 379 ( 5 ) are controlled by a ring tuning control circuit  381 . 
     The optical waveguide  373  extends past each of the ring resonators  375 ( 1 )- 375 ( 5 ). As the five modulated light streams travel through the optical waveguide  373  past the ring resonators  375 ( 1 )- 375 ( 5 ), the wavelengths λ 1  to λ 5  of the laser light optically couple into the ring resonators  375 ( 1 )- 375 ( 5 ) based on the resonant wavelengths at which the ring resonators  375 ( 1 )- 375 ( 5 ) are operated. In this manner, wavelength λ 1  couples into ring resonator  375 ( 1 ). Wavelength λ 2  couples into ring resonator  375 ( 2 ). Wavelength λ 3  couples into ring resonator  375 ( 3 ). Wavelength λ 4  couples into ring resonator  375 ( 4 ). Wavelength λ 5  couples into ring resonator  375 ( 5 ). 
     The receiver circuit  377 ( 1 ) generates the electrical data communication stream b 0  as an output based on the light of wavelength λ 1  coupled into the ring resonator  375 ( 1 ) from the optical waveguide  373 . The receiver circuit  377 ( 2 ) generates the electrical data communication stream b 1  as an output based on the light of wavelength λ 2  coupled into the ring resonator  375 ( 2 ) from the optical waveguide  373 . The receiver circuit  377 ( 3 ) generates the electrical data communication stream b 2  as an output based on the light of wavelength λ 3  coupled into the ring resonator  375 ( 3 ) from the optical waveguide  373 . The receiver circuit  377 ( 4 ) generates the electrical data communication stream b 3  as an output based on the light of wavelength λ 4  coupled into the ring resonator  375 ( 4 ) from the optical waveguide  373 . The receiver circuit  377 ( 5 ) generates the electrical data communication stream b 4  as an output based on the light of wavelength λ 5  coupled into the ring resonator  375 ( 5 ) from the optical waveguide  373 . The receiver circuits  377 ( 1 )- 377 ( 5 ) operate in accordance with clock signals generated by a clock detection and redistribution circuit  383 . 
       FIG. 2F  shows an example transceiver macro implemented within the TeraPHY chip  203 , in accordance with some embodiments. The transceiver macro includes Glue Logic Interfaces (Glue I/F) that include the digital logic required to tie the Optical PHY  287  (Tx and Rx) to the rest of the TeraPHY chip  203 . The Glue I/F can include the electrical PHY  286  on the TeraPHY chip  203 . The transceiver macro also includes a Phase-Locked Loop Up (PLLU) and a Phase-Locked Loop Down (PLLD). The transceiver macro also includes reference clocks (Ref Clks), which are electrical clock signals used to synchronize operations within the transceiver macro. The transceiver macro also includes a Clock Spine, also referred to as a Clock Tree or a Clock Distribution. The Clock Spine is a set of CMOS circuits that distribute the clock generated by the PLLU/PLLD to the Tx Slices and Rx Slices in the transceiver macro so that operations are appropriately synchronized. A laser input (Laser) fiber-to-chip coupling point (e.g., optical grating coupler, optical edge coupler, etc.) is provided for the transceiver macro. A transmitter output (Tx Out) fiber-to-chip coupling point (e.g., optical grating coupler, optical edge coupler, etc.) is provided for the transceiver macro. A receiver input (Rx In) fiber-to-chip coupling point (e.g., optical grating coupler, optical edge coupler, etc.) is provided for the transceiver macro. The transceiver macro also includes an number Transmitter Slices (Tx Slice). The Tx Slice is a set of circuits that make up the transmit function. Tx Slice components include clock distribution to the channels (such as to channels b 0  to b 4  shown in  FIG. 2E ), modulator drivers, modulators (the ring resonators), thermal tuners, and the ring tuning control. The transceiver macro also includes a number of Receiver Slices (Rx Slice). The Rx Slice is a set of circuits that make up the receive function. Rx Slice components include detection and redistribution to the electrical data communication channels (such as to b 0  to b 4  shown in  FIG. 2E ), receivers (e.g., CMOS circuits including components such as transimpedance amplifiers, etc.), photodetectors (the ring resonators), and ring tuning control. In various embodiments, the Tx Slices and the Rx Slices in the TeraPHY chip  203  can be implemented in different ways. Some example Tx Slice and Rx Slice implementations are described in Akhter, Mohammad Shahanshah, et al. “WaveLight: A Monolithic Low Latency Silicon-Photonics Communication Platform for the Next-Generation Disaggregated Cloud Data Centers.”  2017  IEEE 25th Annual Symposium on High-Performance Interconnects (HOTI). IEEE,  2017 , which is incorporated herein by reference in its entirety for all purposes. 
     Arrayed optical waveguide gratings (AWG) are commonly used as optical (de)multiplexers in wavelength division multiplexed (WDM) systems. Passive AWG&#39;s include of an array of optical waveguides of different lengths which determine the frequency channelization of the device. Active AWG&#39;s add active thermal tuning to each optical waveguide in order to finely tune the frequency channelization response of the device and stabilize the frequency channelization response against process and temperature variations. 
     The use of passive AWG&#39;s as filtering elements in dense WDM systems is made difficult by process and temperature variations which can cause a shift in AWG channel characteristics. These issues necessitate use of either a first option that includes a WDM system with tunable laser sources that can adapt to the shift in AWG channel characteristics, or a second option that includes a thermally-stabilized AWG that adapts its frequency characteristics to the dense WDM wavelength grid. Both of the above-mentioned first and second options increase the overall cost and energy footprint of the system. Therefore, it is of interest to have additional options for managing effects of process and temperature variations in dense WDM systems. In this regard, the SmartDistribuTOR modules  111 - 1  through  111 -K provide a small (hence cost-effective) and low-energy adaptive optical multiplexer/demultiplexer (mux/demux) solution. 
       FIG. 3  shows a schematic of one SmartDistribuTOR module  111 - x , ( 111 - x  corresponds to any one of  111 - 1  through  111 -K) with an example downlink fiber wavelength plan for the downlink optical fiber  115  and an example uplink fiber wavelength plan for the uplink optical fiber  117 , in accordance with some embodiments. As shown in  FIG. 3 , the SmartDistribuTOR module  111 - x  enables splitting and aggregation of wavelengths on multiple optical channels within the optical fiber to multiple optical fibers. In some embodiments, dense WDM can be used to pack a large number of optical channels and increase the number of servers reachable via a single pair of optical fibers, e.g., via the downlink optical fiber  115  and the uplink optical fiber  117 . 
     In some embodiments, the downlink optical fiber  115  and the uplink optical fiber  117  can be connected to the duplex connector  113  exposed at a surface of the SmartDistribuTOR module  111 - x . The duplex connector  113  functions to enable connection of two external optical fibers to the downlink optical fiber  115  and the uplink optical fiber  117 , respectively. The example embodiment of  FIG. 3  shows eight optical channels Ch 1  to Ch 8  on the downlink optical fiber  115 , with one modulated wavelength  301 ( 1 )- 301 ( 8 ) per optical channel, respectively, and with one continuous wave wavelength  303 ( 1 )- 303 ( 8 ) per optical channel, respectively. Also, the example embodiment of  FIG. 3  shows eight optical channels Ch 1  to Ch 8  on the uplink optical fiber  117 , with one modulated wavelength  305 ( 1 )- 305 ( 8 ) per optical channel, respectively. In some embodiments, each modulated wavelength  301 ( 1 )- 301 ( 8 ) and  305 ( 1 )- 305 ( 8 ) can carry 100 Gbps of data, by way of example. In some embodiments, the wavelengths conveyed to and/or from the SmartDistribuTOR module  111 - x  are in the O-band wavelength range. In some embodiments, the wavelengths conveyed to and/or from the SmartDistribuTOR module  111 - x  are in the C-band or L-band wavelength range. 
       FIG. 3  also shows the tunable optical DEMUX block  119  within the SmartDistribuTOR module  111 - x , in accordance with some embodiments. The tunable optical DEMUX block  119  is configured to split wavelengths on the multiple optical channels Ch 1  to Ch 8  within the downlink optical fiber  115  to multiple optical waveguides/fibers  123 ( 1 ) to  123 ( 8 ), respectively. Each of the multiple optical waveguides/fibers  123 ( 1 )- 123 ( 8 ) is connected to a respective duplex connector  307 ( 1 )- 307 ( 8 ) exposed at a surface of the SmartDistribuTOR module  111 - x . The duplex connectors  307 ( 1 )- 307 ( 8 ) function to enable connection of the optical waveguides/fibers  123 ( 1 )- 123 ( 8 ) to corresponding external optical fibers. 
       FIG. 3  also shows the tunable optical MUX block  121  within the SmartDistribuTOR module  111 - x , in accordance with some embodiments. The tunable optical MUX block  121  is configured to aggregate multiple wavelengths from multiple optical waveguides/fibers  125 ( 1 )- 125 ( 8 ) onto the multiple optical channels Ch 1  to Ch 8 , respectively, within the uplink optical fiber  117 . Each of the multiple optical waveguides/fibers  125 ( 1 )- 125 ( 8 ) is connected to a respective one of the duplex connectors  307 ( 1 )- 307 ( 8 ) exposed at the surface of the SmartDistribuTOR module  111 - x . The duplex connectors  307 ( 1 )- 307 ( 8 ) function to enable connection of the optical waveguides/fibers  125 ( 1 )- 125 ( 8 ) to corresponding external optical fibers. 
       FIG. 4  shows a schematic of the tunable optical DEMUX block  119  within the SmartDistribuTOR module  111 - x , in accordance with some embodiments. The tunable optical DEMUX block  119  includes an input optical waveguide  401 . In various embodiments, the input optical waveguide  401  can be an optical fiber or a solid optical waveguide structure formed of silicon, glass, or other suitable optical waveguide material. The input optical waveguide  401  is coupled to receive light incoming from the downlink optical fiber  115 . In some embodiments, the polarization of light coming into the tunable optical DEMUX block  119  is unknown, which necessitates a downlink polarization management block  403  to be integrated together with the tunable optical DEMUX block  119  on the same die. In the tunable optical DEMUX block  119 , polarization management/control is needed only on the input optical waveguide  401 , as shown by the downlink polarization management block  403 . In some embodiments, the downlink polarization management block  403  includes a polarization splitting optical grating. In some embodiments, the downlink polarization management block  403  includes a polarization independent optical coupler followed by a polarization splitter-rotator. In some embodiments, after polarization splitting is done by the downlink polarization management block  403 , the two paths (polarizations) are combined into a single optical waveguide  405  using a thermally controlled Mach-Zehnder interferometer tuned to maximize the optical power on each wavelength at its output. 
     The downlink polarization management block  403  is electrically connected to an embedded master controller  421 , as indicated by a connection  409 . The embedded master controller  421  is configured to control operation of the downlink polarization management block  403  by directing transmission of control signals through the connector  409 . The embedded master controller  421  is also configured to receive monitored/measured signals from the downlink polarization management block  403  through the connection  409 . It should be understood that the connection  409  can include multiple independent electrical conductors and/or electrical traces in various embodiments. 
     The tunable optical DEMUX block  119  includes a tunable optical ring resonator filterbank  407  that includes (N) optical ring resonator filters  413 ( 1 )- 413 (N) corresponding to Channel  1  through Channel N, respectively. Each of the optical ring resonator filters  413 ( 1 )- 413 (N) includes at least one ring resonator  417 ( 1 )- 417 (N), respectively, arranged next to the optical waveguide  405  to define a desired channel transfer function. In some embodiments, each of the optical ring resonator filters  413 ( 1 )- 413 (N) includes at least one embedded heating element  415 ( 1 )- 415 (N), respectively, that is connected and configured for control by an embedded electronic control loop  419 ( 1 )- 419 (N), respectively. In some embodiments, the optical ring resonator filters  413 ( 1 )- 413 (N) are designed in a Complementary Metal-Oxide Semiconductor (CMOS) Silicon on Insulator (SOI) process, and are integrated monolithically on the same die as the transistors that comprise the circuitry of the embedded electronic control loops  419 ( 1 )- 419 (N). In some embodiments, each of the optical ring resonator filters  413 ( 1 )- 413 (N) includes a respective embedded photo-detector, which is used/operated as a sensor for wavelength lock. 
     In some embodiments, a given ring resonator  417 ( 1 )- 417 (N) of a corresponding optical ring resonator filter  413 ( 1 )- 413 (N) is heated by driving electrical current directly through the silicon body of the ring resonator  417 ( 1 )- 417 (N). Because the ring resonator  417 ( 1 )- 417 (N) is resistive, the ring resonator  417 ( 1 )- 417 (N) will heat up when electrical current is driven through it. In these embodiments, a change in the electrical current that is driven through the ring resonator  417 ( 1 )- 417 (N) will occur due to photon-induced carrier generation in the ring resonator  417 ( 1 )- 417 (N). This change in the electrical current due to photon-induced carrier generation in the ring resonator  417 ( 1 )- 417 (N) can be used to sense the proximity of laser wavelength to the resonance wavelength of the ring resonator  417 ( 1 )- 417 (N). In some embodiments, when a given optical ring resonator filter  413 ( 1 )- 413 (N) is heated by driving electrical current directly through the silicon body of the corresponding ring resonator  417 ( 1 )- 417 (N), the embedded heating element  415 ( 1 )- 415 (N) is not disposed and/or used within the given optical ring resonator filter  413 ( 1 )- 413 (N). 
     In some embodiments, the ring resonator  417 ( 1 )- 417 (N) is a p-i-n doped type of ring structure with the p and n region being the contact regions used to sense the generated photon-induced carriers. In these embodiments, the embedded heating element  415 ( 1 )- 415 (N) can be a separate structure formed outside of the ring resonator  417 ( 1 )- 417 (N). When the ring resonator  417 ( 1 )- 417 (N) is defined as the p-i-n doped type of ring structure, the ring resonator  417 ( 1 )- 417 (N) can be reversed biased to sweep the generated photon-induced charge carriers into a sensing circuit that then drives the embedded electronic control loop  419 ( 1 )- 419 (N) to lock the optical ring resonator filter  413 ( 1 )- 413 (N) to a particular wavelength. Also, in some embodiments, the silicon body of the ring resonator  417 ( 1 )- 417 (N) has defect states that enable generation of photon-induced charge carriers, which is enough to sense the optical power in the ring resonator  417 ( 1 )- 417 (N) without embedding a photodetector. 
     In some embodiments, each embedded electronic control loop  419 ( 1 )- 419 (N) includes an analog front-end which converts sensed electrical current into a voltage. Also, each embedded electronic control loop  419 ( 1 )- 419 (N) includes a digitizer that generates a digital representation of the voltage output by the analog front-end. Also, each embedded electronic control loop  419 ( 1 )- 419 (N) includes control loop logic and a digital-to-analog converter that outputs electrical current to drive the embedded heating element  415 ( 1 )- 415 (N) or to drive electrical current directly through the silicon body of the ring resonator  417 ( 1 )- 417 (N). In some embodiments, the embedded master controller  421  controls each embedded electronic control loop  419 ( 1 )- 419 (N) through respective electrical connections  423 ( 1 )- 423 (N) to ensure locking of each optical ring resonator filter  413 ( 1 )- 413 (N) to a desired wavelength in the dense WDM spectrum. The resonance wavelengths of the ring resonators  417 ( 1 )- 417 (N) are controlled such that the optical ring resonator filters  413 ( 1 )- 413 (N) optically couple a particular wavelength onto a corresponding output optical waveguide  425 ( 1 )- 425 (N), thereby providing the modulated wavelengths  301 ( 1 )- 301 (N) on the channels Ch 1  to ChN, respectively. 
       FIG. 5  shows a schematic of the tunable optical MUX block  121  within the SmartDistribuTOR module  111 - x , in accordance with some embodiments. The tunable optical MUX block  121  includes N input optical waveguides  501 ( 1 )- 501 (N). In various embodiments, each of the input optical waveguides  501 ( 1 )- 501 (N) can be an optical fiber or a solid optical waveguide structure formed of silicon, glass, or other suitable optical waveguide material. Each of the input optical waveguides  501 ( 1 )- 501 (N) is coupled to receive light incoming from the multiple optical waveguides  125 ( 1 )- 125 (N). In some embodiments, the polarization of light coming into the tunable optical MUX block  121  is unknown, which necessitates a number N of polarization management blocks  503 ( 1 )- 503 (N) to be integrated together with the tunable optical MUX block  121  on the same die. In the tunable optical MUX block  121 , polarization management/control is provided for each of the input optical waveguides  501 ( 1 )- 501 (N), as shown by the polarization management blocks  503 ( 1 )- 503 (N). In some embodiments, each of the polarization management blocks  503 ( 1 )- 503 (N) includes a polarization splitting optical grating. In some embodiments, each of the polarization management blocks  503 ( 1 )- 503 (N) includes a polarization independent optical coupler followed by a polarization splitter-rotator. In some embodiments, after polarization splitting is done by the polarization management block  503 ( 1 )- 503 (N), the two paths (polarizations) are combined into a single optical waveguide  505 ( 1 )- 505 (N) using a thermally controlled Mach-Zehnder interferometer tuned to maximize the optical power on each wavelength at its output. 
     Each polarization management block  503 ( 1 )- 503 (N) is electrically connected to an embedded master controller  509 , as indicated by electrical connections  507 ( 1 )- 507 (N). The embedded master controller  509  is configured to control operation of the polarization management blocks  503 ( 1 )- 503 (N) by directing transmission of control signals through the connections  507 ( 1 )- 507 (N). The embedded master controller  509  is also configured to receive monitored/measured signals from the polarization management blocks  503 ( 1 )- 503 (N) through the connections  507 ( 1 )- 507 (N). It should be understood that each of the connections  507 ( 1 )- 507 (N) can include multiple independent electrical conductors and/or electrical traces in various embodiments. 
     The tunable optical MUX block  121  includes a tunable optical ring resonator filterbank  511  that includes (N) optical ring resonator filters  513 ( 1 )- 513 (N) corresponding to Channel  1  through Channel N, respectively. Each of the optical ring resonator filters  513 ( 1 )- 513 (N) includes at least one ring resonator  517 ( 1 )- 517 (N), respectively, arranged next to a respective one of the optical waveguides  505 ( 1 )- 505 (N) to define a desired channel transfer function. In some embodiments, each of the optical ring resonator filters  513 ( 1 )- 513 (N) includes at least one embedded heating element  515 ( 1 )- 515 (N), respectively, that is connected and configured for control by an embedded electronic control loop  519 ( 1 )- 519 (N), respectively. In some embodiments, the optical ring resonator filters  513 ( 1 )- 513 (N) are designed in a CMOS SOI process, and are integrated monolithically on the same die as the transistors that comprise the circuitry of the embedded electronic control loops  519 ( 1 )- 519 (N). In some embodiments, each of the optical ring resonator filters  513 ( 1 )- 513 (N) includes a respective embedded photo-detector, which is used/operated as a sensor for wavelength lock. 
     In some embodiments, a given ring resonator  517 ( 1 )- 517 (N) of a corresponding optical ring resonator filter  513 ( 1 )- 513 (N) is heated by driving electrical current directly through the silicon body of the ring resonator  517 ( 1 )- 517 (N). Because the ring resonator  517 ( 1 )- 517 (N) is resistive, the ring resonator  517 ( 1 )- 517 (N) will heat up when electrical current is driven through it. In these embodiments, a change in the electrical current that is driven through the ring resonator  517 ( 1 )- 517 (N) will occur due to photon-induced charge carrier generation in the ring resonator  517 ( 1 )- 517 (N). This change in the electrical current due to photon-induced charge carrier generation in the ring resonator  517 ( 1 )- 517 (N) can be used to sense the proximity of laser wavelength to the resonance wavelength of the ring resonator  517 ( 1 )- 517 (N). In some embodiments, when a given optical ring resonator filter  513 ( 1 )- 513 (N) is heated by driving electrical current directly through the silicon body of the corresponding ring resonator  517 ( 1 )- 517 (N), the embedded heating element  515 ( 1 )- 515 (N) is not disposed and/or used within the given optical ring resonator filter  513 ( 1 )- 513 (N). 
     In some embodiments, the ring resonator  517 ( 1 )- 517 (N) is a p-i-n doped type of ring structure with the p and n region being the contact regions used to sense the generated photon-induced charge carriers. In these embodiments, the embedded heating element  515 ( 1 )- 515 (N) can be a separate structure formed outside of the ring resonator  517 ( 1 )- 517 (N). When the ring resonator  517 ( 1 )- 517 (N) is defined as the p-i-n doped type of ring structure, the ring resonator  517 ( 1 )- 517 (N) can be reversed biased to sweep the generated photon-induced charge carriers into a sensing circuit that then drives the embedded electronic control loop  519 ( 1 )- 519 (N) to lock the optical ring resonator filter  513 ( 1 )- 513 (N) to a particular wavelength. Also, in some embodiments, the silicon body of the ring resonator  517 ( 1 )- 517 (N) has defect states that enable generation of photon-induced charge carriers, which is enough to sense the optical power in the ring resonator  517 ( 1 )- 517 (N) without embedding an actual photodetector. 
     In some embodiments, each embedded electronic control loop  519 ( 1 )- 519 (N) includes an analog front-end which converts sensed electrical current into a voltage. Also, each embedded electronic control loop  519 ( 1 )- 519 (N) includes a digitizer that generates a digital representation of the voltage output by the analog front-end. Also, each embedded electronic control loop  519 ( 1 )- 519 (N) includes control loop logic and a digital-to-analog converter that outputs electrical current to drive the embedded heating element  515 ( 1 )- 515 (N) or to drive electrical current directly through the silicon body of the ring resonator  517 ( 1 )- 517 (N). In some embodiments, the embedded master controller  509  controls each embedded electronic control loop  519 ( 1 )- 519 (N) through respective electrical connections  523 ( 1 )- 523 (N) to ensure locking of each optical ring resonator filter  513 ( 1 )- 513 (N) to a desired wavelength in the dense WDM spectrum. 
     The tunable optical ring resonator filterbank  511  operates the (N) optical ring resonator filters  513 ( 1 )- 513 (N) to combine selected ones of the (N) modulated wavelengths  305 ( 1 )- 305 (N) received on the multiple optical waveguides  125 ( 1 )- 125 (N) onto an output optical waveguide  521 . In some embodiments, the tunable optical MUX block  121  can be controlled to combine all (N) modulated wavelengths  305 ( 1 )- 305 (N) onto the output optical waveguide  521 . In some embodiments, the tunable optical MUX block  121  can be controlled to combine less than all of the (N) modulated wavelengths  305 ( 1 )- 305 (N) onto the output optical waveguide  521 , where the particular ones of the modulated wavelengths  305 ( 1 )- 305 (N) that are combined onto the output optical waveguide  521  can be selected through control of the optical ring resonator filters  513 ( 1 )- 513 (N) by way of the embedded master controller  509 . The output optical waveguide  521  is optically connected to the uplink optical fiber  117 . 
     In some embodiments, the SmartDistribuTOR module  111 - x  is autonomous (self-managed) upon power-up. In some embodiments, the SmartDistribuTOR module  111 - x  can be managed remotely through a microprocessor/microcontroller embedded on the same die/chip or on the same module board as the SmartDistribuTOR module  111 - x . In various embodiments, the SmartDistribuTOR module  111 - x  disclosed herein provides for robust, temperature-variation-insensitive, process-variation-insensitive, and polarization-variation-insensitive optical multiplexing and demultiplexing for dense WDM systems. In various embodiments, the SmartDistribuTOR module  111 - x  can operate in either the O-band wavelength range, the C-band wavelength range, or the L-band wavelength range. The SmartDistribuTOR module  111 - x  has low energy consumption and has a small area footprint on the die/chip. In various embodiments, the SmartDistribuTOR module  111 - x  is a self-adaptive system that does not require external control. 
     In some embodiments, the SmartDistribuTOR module  111 - x  disclosed herein provides a tunable optical multiplexer/demultiplexer based on tunable optical ring resonator filterbank operation with embedded heaters controlled by an electronic control loop. In some embodiments, the electronic control loop has a local per channel controller and global master controller. In some embodiments, the electronic control loop is integrated on the same die/chip as the optical ring resonators. In some embodiments, an embedded optical polarization management block is coupled to the electronic control loop. 
     In some embodiments, the tunable optical ring resonator filterbank is configured to enable detection of the proximity of the resonance to wavelength by way of charge carrier generation within the passive ring resonator filter. In some embodiments, the passive ring resonator filter has an embedded heater. In some embodiments, the proximity of the resonance to wavelength is detected through a change in heater electrical current. In some embodiments, an embedded photodetector is provided in a small portion/slice of the passive ring resonator filter. 
     In some embodiments, the SmartDistribuTOR module  111 - x  disclosed herein provides for tunable ring resonator multiplexing/demultiplexing in dense WDM systems to multiplex/demultiplex wavelengths to servers in a server rack. In some embodiments, the SmartDistribuTOR module  111 - x  disclosed herein is located in a top region of the server rack. In some embodiments, the SmartDistribuTOR module  111 - x  provides for multi-ring per channel add/drop of wavelength(s) with embedded resonance control. 
     In current data-centers, servers are organized in racks. Each rack includes a Top-of-Rack (TOR) switch, which connects the servers in the rack to the rest of the data-center network (typically called the core or the spine). Each server is connected to the TOR switch via copper cables. Optical pluggable transceivers connect the TOR switch with the rest of the data-center network. Systems and methods are disclosed herein that utilize highly integrated electronic-photonic transceiver technology to enable one or more direct optical links from the data-center network to each server, without needing to have the optical source component, i.e., laser, in the server-side electro-optical module. The server-side electro-optical module can be referred to as a Reverb module. 
       FIG. 6  shows a schematic of a server-side electro-optical module  601  (“Reverb”) within a server  600 , in accordance with some embodiments. The server  600  represents any of the servers  1  through M shown in  FIG. 1 . Also, the electro-optical module  601  represents any of the electro-optical modules Rvb- 1  through Rvb-M shown in  FIG. 1 . In some embodiments, the electro-optical module  601  includes a Reverb chip  603  and a SerDes chip  605 . In some embodiments, the electro-optical module  601  includes the Reverb chip  603  without the SerDes chip  605 . In some embodiments, the Reverb chip  603  includes optical components and electrical components integrated monolithically together on the same die. In some embodiments, the Reverb chip  603  includes only optical components. In some embodiments, the electro-optical module  601  is an active-optical-cable (AOC), where the optical fiber that connects the electro-optical module  601  to the SmartDistribuTOR module  111 - x  in the same rack is directly attached to the Reverb chip  603 . In some embodiments, the Reverb chip  603  is optical fiber pigtailed and connectorized at the edge of the electro-optical module  601 . 
     The electro-optical module  601  couples to an optical fiber pair  607  and receives and transmits optical signals on the optical fiber pair  607 . In some embodiments, the optical fiber pair  607  is terminated with a connector  609 , such as with an LC duplex connector or other suitable type of optical fiber connector. A first optical fiber  607 A of the optical fiber pair  607  carries a modulated wavelength with downlink data and one unmodulated (continuous wave (CW)) wavelength to the server  600  on which the electro-optical module  601  is installed. A second optical fiber  607 B of the optical fiber pair  607  carries a modulated wavelength with uplink data from the server  600  on which the electro-optical module  601  is installed to the data-center network. In some embodiments, the optical fibers  607 A,  607 B of the optical fiber pair  607  are directly pigtailed to the Reverb chip  603  in the electro-optical module  601 , so as to constitute an Active Optical Cable (AOC). In some embodiments, the Reverb chip  603  is pigtailed and the pigtail is connectorized on a face-plate of the electro-optical module  601  with a connector, such as with an LC duplex connector or other suitable type of optical fiber connector. 
     The Reverb chip  603  is configured to receive the modulated downlink wavelength and convert the received modulated downlink wavelength to an electrical data stream, and provide the electrical data stream to the server  600  through an electrical bus  611  and a network interface card  613 . The Reverb chip  603  is also configured to modulate the received unmodulated (CW) wavelength with uplink data traffic for transmission from the server  600  on which the electro-optical module  601  is installed to the rest of the data-center network. The Reverb chip  603  receives electrical data communication signals from the server  600  through the network interface card  613  an the electrical bus  611 . The Reverb chip  603  modulates the unmodulated CW wavelength to generate modulated light that conveys the data included in the electrical data communication signals received from the server  600 . In some embodiments, the SerDes chip  605  operates to serialize parallel data received through the electrical bus  611  from the server  600  in route to the Reverb chip  603 . Also, in some embodiments, the SerDes chip  605  operates to deserialize serial data into parallel data for transmission through the electrical bus  611  and network interface card  613  to the server  600 . 
     In some embodiments, the Reverb chip  603  is an electronic-photonic chip and includes both photonic components (optical couplers, optical waveguides, optical modulators, photodetectors, optical filters, etc.) and electronic components (transistors, electrical conductors, etc.). In some embodiments in which the Reverb chip  603  is the electronic-photonic chip, the photonic components and the electronic components of the Reverb chip  603  are integrated monolithically on the same die formed in a CMOS fabrication process. In some embodiments, the Reverb chip  603  is configured to include just the photonic components, while the SerDes chip  605  is configured to include the electronic components and circuits that interface and control the photonic Reverb chip  603 . In some embodiments in which the Reverb chip  603  is the electronic-photonic chip, the Reverb chip  603  includes electronic circuitry that controls a polarization and a resonant wavelength of the photonic components within the Reverb chip  603 . In some embodiments in which the Reverb chip  603  is the electronic-photonic chip, the Reverb chip  603  includes additional non-retimed electronic interface circuitry (such as receivers, modulator drivers, etc.). In some embodiments in which the Reverb chip  603  is the electronic-photonic chip, the Reverb chip  603  also includes retiming electronic circuits (serializer, deserializer, clock generators—phase locked loop and clock-data-recovery loop, etc.). 
       FIG. 7  shows a schematic of the Reverb chip  603 , in accordance with some embodiments. The Reverb chip  603  includes a downlink polarization control block  703 , a downlink data receiver block  709 , an uplink data modulator block  711 , and an electrical input/output (I/O) block  713 . The Reverb chip  603  includes an optical waveguide  701  through which the downlink modulated light  704  and the CW light  702  is received from the optical fiber  607 A. The downlink polarization control block  703  is optically connected to receive the downlink modulated light  704  and the CW light  702  from the optical waveguide  701 . In some embodiments, the downlink polarization block  703  includes a polarization splitting optical grating. In some embodiments, the downlink polarization block  703  includes a polarization independent optical coupler followed by a polarization splitter-rotator. In some embodiments, after polarization split in the downlink polarization block  703 , the two paths (polarizations) are combined into a single optical waveguide  705  using a thermally controlled Mach-Zehnder interferometer, tuned to maximize the optical power on each optical wavelength at its output. 
     In some embodiments, the downlink data receiver block  709  optically couples to an optical output of the downlink polarization control block  703 . The downlink data receiver block  709  is configured to filter the downlink modulated wavelength  704  and convert the filtered downlink modulated wavelength  704  into an electrical signal. The downlink data receiver block  709  is also configured to pass the unmodulated (CW) wavelength  702  to the uplink data modulator block  711 . The uplink data modulator block  711  is configured to imprint an uplink electrical data stream on the unmodulated (CW) wavelength  702  to create an uplink modulated wavelength light signal  706 . The uplink data modulator block  711  is configured to transmit the uplink modulated wavelength light signal  706  through an optical waveguide  707  to the uplink optical fiber  607 B. 
     In some embodiments, the downlink data receiver block  709  includes one or more resonant ring filters configured to drop one or more modulated downlink data wavelengths to one or more corresponding photodetectors. In some embodiments, the corresponding photodetector is integrated in the resonant ring filter. In some embodiments, the resonant ring filter is tuned to the modulated downlink data wavelengths using an embedded heater. In some embodiments, the embedded heater of the resonant ring filter is controlled by an embedded digital control loop which senses the amount of light that the resonant ring drops (or absorbs). In some embodiments, the digital control loop for the embedded heater of the resonant ring filter is placed on another CMOS chip in the electro-optical module  601 . 
     In some embodiments, the uplink data modulator block  711  includes one or more resonant ring modulators. In some embodiments, the resonant ring modulators of the uplink data modulator block  711  are tuned to one or more CW wavelengths using embedded heaters. In some embodiments, the embedded heater of the resonant ring modulator is controlled by an embedded digital control loop which senses the amount of light that the resonant ring drops (or absorbs). In some embodiments, the digital control loop for the embedded heater of the resonant ring modulator is placed on another CMOS chip in the electro-optical module  601 . 
     In some embodiments, the electro-optical module  601  receives one modulated wavelength and one CW wavelength on the downlink optical fiber  607 A, and modulates the received CW wavelength from the downlink optical fiber  607 A onto the uplink optical fiber  607 B. In some embodiments, the electro-optical module  601  receives multiple modulated wavelengths and multiple CW wavelengths on the downlink optical fiber  607 A, and modulates the received CW wavelengths from the downlink optical fiber  607 A onto the uplink optical fiber  607 B. In some embodiments, the electro-optical module  601  is configured to receive optical signals from multiple downlink optical fibers  607 A and provide optical signals to multiple uplink optical fibers  607 B. In these embodiments, each of the multiple downlink optical fibers  607 A conveys one or more modulated wavelength(s) and one or more unmodulated CW wavelength(s) to the electro-optical module  601 , and each of the multiple uplink optical fibers  607 B conveys one or more modulated wavelength(s) from the electro-optical module  601 . In some embodiments, the wavelengths conveyed to and/or from the electro-optical module  601  are in the O-band wavelength range. In some embodiments, the wavelengths conveyed to and/or from the electro-optical module  601  are in the C-band or L-band wavelength range. 
       FIG. 8  shows an example uplink and downlink wavelength plan per downlink optical fiber  607 A and uplink optical fiber  607 B, in accordance with some embodiments. In some embodiments, dense wavelength division multiplexing can be used to pack a large number of optical channels and increase the number of servers reachable via a single uplink and downlink optical fiber pair  607 . The example embodiment of  FIG. 8  shows eight optical channels Ch 1  to Ch 8  on the downlink fiber  607 A, with one modulated wavelength  301 ( 1 )- 301 ( 8 ) per optical channel, respectively, and with one continuous wave wavelength  303 ( 1 )- 303 ( 8 ) per optical channel, respectively. Also, the example embodiment of  FIG. 8  shows eight optical channels Ch 1  to Ch 8  on the uplink fiber  607 B, with one modulated wavelength  305 ( 1 )- 305 ( 8 ) per optical channel, respectively. In some embodiments, each modulated wavelength  301 ( 1 )- 301 ( 8 ) and  305 ( 1 )- 305 ( 8 ) can carry 100 Gbps of data, by way of example. In various embodiments, a passive or active optical multiplexer/demultiplexer, such as the SmartDistribuTOR module  111 - x , separates one or more channels to be forwarded to the electro-optical module  601  in each server. 
     It should be understood that the electro-optical module  601  enables high-bandwidth, low-energy and low-cost optical connection from each server to the data-center network by leveraging advances in electronic-photonic integration in CMOS and low-cost dense wavelength division multiplexing (DWDM). Miniaturization of optical components in standard CMOS chips and temperature control of those components using on-chip digital logic for auto-feedback loops enables a reliable, low-cost, and high-bandwidth system for connecting racks of servers. This interconnectivity of thousands of servers enables disaggregation of compute, memory, and storage resources across many racks, making flexible real-time allocation of compute jobs across racks possible. 
     In various embodiments, the electro-optical module  601  provides for having no lasers in the servers  1  through M, because of continuous wave laser light forwarding from the TORminator module  107  through the SmartDistribuTOR module  111 - x  to the electro-optical module  601  in the server. The electro-optical module  601  also provides for a ubiquitous server-side module in that any server module can work at any DWDM wavelength in the wavelength range of interest (e.g., O-band). The electro-optical module  601  also provides for operation over standard duplex single mode (SM) optical fiber pairs, with a single fiber pair connection to server. The electro-optical module  601  also provides for scalability through parallel transmission and processing of different wavelengths of light. 
     In some embodiments, the electro-optical module  601  does not have an onboard laser, but rather is configured to receive at least one CW wavelength and at least one modulated wavelength. The electro-optical module  601  is configured to modulate the CW wavelength for uplink data transmission. The electro-optical module  601  includes the Reverb chip  603  that can include silicon-photonic components. In some embodiments, the Reverb chip  603  can include monolithically integrated transistors and photonic components. In some embodiments, the Reverb chip  603  can include photonic resonant components with embedded heaters. In some embodiments, the Reverb chip  603  can include photonic resonant components and embedded tuning circuits. In some embodiments, the Reverb chip  603  can include photonic resonant components and embedded tuning circuits, along with photonic link transceivers (receivers and modulator drivers). In some embodiments, the Reverb chip  603  can include photonic resonant components and embedded tuning circuits, along with photonic link transceivers (receivers and modulator drivers), and a retimed interface (serializer and deserializer). In some embodiments, the Reverb chip  603  can include photonic resonant components and embedded tuning circuits, and photonic link transceivers (receivers and modulator drivers), and a retimed interface (serializer and deserializer), and a clock and data-recover loop. In some embodiments, the Reverb chip  603  includes active polarization control/combining in the Reverb chip  603 . In some embodiments, the Reverb chip  603  includes a polarization splitting coupler. In some embodiments, the Reverb chip  603  includes a polarization independent coupler and a polarization splitter/rotator. 
     In some embodiments, the Reverb chip  603  includes one or more resonant filters to drop the modulated downlink wavelengths. In some embodiments, the one or more resonant filters include passive, tunable ring filters. In some embodiments, the one or more resonant filters include active, tunable, ring-resonator-based photodetectors. In some embodiments, the Reverb chip  603  includes one or more tunable resonant modulators to modulate the received CW wavelengths for the uplink data. 
       FIG. 9  shows the TORminator system  100  implemented across multiple racks within a datacenter, in accordance with some embodiments. The example of  FIG. 9  corresponds to the TORminator system  100  example of  FIG. 1 . Therefore, 128 servers (M=128) are distributed across 16 racks (K=16)  901 - 1  to  901 - 16 , with each rack including a separate SmartDistribuTOR module  111 - 1  to  111 - 16  and 8 servers (N=8). One rack (rack  901 - 1  in the example of  FIG. 9 ) includes the EOR/MOR switch linecard  101  that services all 16 racks  901 - 1  to  901 - 16 . In this configuration, the TORminator system  100  provides for optical data communication between the EOR/MOR switch linecard  101  and each of the 128 servers in the 16 racks. 
     It should be understood that the TORminator system  100  disclosed herein creates large pools of highly interconnected servers by leveraging advances in electronic-photonic integration in CMOS and low-cost dense wavelength division multiplexing (DWDM) in the O-band wavelength range. Miniaturization of optical components in standard CMOS chips and robust lock control of those components enable a reliable, low-cost, and high-bandwidth TORminator system  100  for optically connecting multiple racks of servers. It should be understood that the TORminator system  100  disclosed herein can be scaled to interconnect thousands of servers. This interconnectivity of thousands of servers enables disaggregation of compute, memory, and storage resources across many racks, making flexible real-time allocation of compute jobs across racks possible. 
     In various embodiments, the TORminator system  100  disclosed herein provides for low optical fiber count due to efficient wavelength mux-demux for dense wavelength-division multiplexing in the O-band (O-DWDM). 
     In various embodiments, the TORminator system  100  disclosed herein provides for optical communication between multiple servers without having lasers in the multiple servers, because the laser light forwarding from the TORminator module  107  through the SmartDistribuTOR modules  111 - x  to the servers. The TORminator system  100  also provides a ubiquitous server-side electro-optical module  601  that can work at any O-DWDM wavelength. The TORminator system  100  also provides for operation over standard duplex single mode optical fiber pairs. In some embodiments, the TORminator system  100  also provides a low-power system with uncooled lasers within the laser chip  205  in the TORminator module  107  on the EOR/MOR switch linecard  101 . The TORminator system  100  also provides a pluggable architecture with options for in-package integration of the TeraPHY chip  203  with a switch chip (ASIC) within the rack switch  103 . The TORminator system  100  also provides for scalability through parallel transmission and processing of different wavelengths of light. 
     In some embodiments, the TORminator system  100  includes the TORminator module  107  in electrical data communication with the rack switch  103 , and the TORminator module  107  in optical data communication with the SmartDistribuTOR module  111 - x , and the SmartDistribuTOR module  111 - x  in optical data communication with the electro-optical modules  601  of servers. The TORminator system  100  provides for forwarding of laser light to the servers for optical uplink of data (even without the top-of-the-rack optical mux/demux). The TORminator system  100  also provides for multiple channels per optical fiber (one or more for each server). The TORminator system  100  also provides for no laser or optical amplifier at the server side. 
     In some embodiments, the TORminator module  107  includes the TeraPHY chip  203  and the laser chip  205 . In some embodiments, the TORminator module  107  can provide the SOA array chip  207  on the downlink. In some embodiments, the TORminator module  107  can provide the SOA array chip  209  on the uplink (capable of handling both polarizations). In some embodiments, the TORminator module  107  can provide both the SOA array chip  207  on the downlink and the SOA array chip  209  on the uplink (capable of handling both polarizations). 
     In some embodiments, the TORminator module  107  is edge-connector pluggable. In some embodiments, the TORminator module  107  is on a mezzanine card. In some embodiments, one or more components of the TORminator module  107  are directly socketed on the EOR/MOR switch linecard  101 . In some embodiments, the TeraPHY chip  203  of the TORminator module  107  is co-packaged with the switch chip within the rack switch  103 , while the laser chip  205  and SOA array chips  207 ,  209  of the TORminator module  107  are either in the TORminator module  107  or socketed on the EOR/MOR switch linecard  101 . 
     In some embodiments, the TeraPHY chip  203  of the TORminator module  107  includes multiple transceiver macros, with each transceiver macro being of multiple wavelength slices. In some embodiments, the slices of the TeraPHY chip  203  include electrical and optical components (transmit and receive macro slices). In some embodiments, an electrical link between the TeraPHY chip  203  and the switch chip in the rack switch  103  is retimed. In some embodiments, an electrical link between the TeraPHY chip  203  and the switch chip in the rack switch  103  is not retimed. In some embodiments, the slices of the TeraPHY chip  203  include only optical components. In some embodiments, modulator slices of the TeraPHY chip  203  modulate a portion of the laser light wavelengths provided by the laser chip  205  and leave a remainder of the laser light wavelengths provided by the laser chip  205  for use by the servers to uplink data. 
     In some embodiments, a data communication system includes a rack switch  103 , a TORminator module  107 , a downlink optical fiber d 1  to dK, an uplink optical fiber u 1  to uK, and a SmartDistribuTOR module  111 - x . The TORminator module  107  is electrically connected to the rack switch  103 . The TORminator module  107  is configured to convert a number (N) of downlink data communication electrical signals received from the rack switch  103  into corresponding N downlink data communication optical signals, where N is greater than one. Each of the N downlink data communication optical signals has a different optical wavelength. The TORminator module  107  is configured to simultaneously direct the N downlink data communication optical signals to a first downlink optical port (half of each of  109 - 1  to  109 -K). The TORminator module  107  is configured to generate N different wavelengths of continuous wave laser light and simultaneously direct the N different wavelengths of continuous wave laser light to the first downlink optical port (half of each of  109 - 1  to  109 -K). The TORminator module  107  includes a first uplink optical port (half of each of  109 - 1  to  109 -K). The TORminator module  107  is configured to convert N uplink data communication optical signals received through the first uplink optical port (half of each of  109 - 1  to  109 -K) into N uplink data communication electrical signals. The TORminator module  107  is configured to transmit the N uplink data communication electrical signals to the rack switch  103 . 
     The downlink optical fiber d 1  to dK has a first end optically coupled to the first downlink optical port (half of each of  109 - 1  to  109 -K) of the TORminator module  107 . The uplink optical fiber u 1  to uK has a first end optically coupled to the first uplink optical port (half of each of  109 - 1  to  109 -K) of the TORminator module  107 . The SmartDistribuTOR module  111 - x  has a second downlink optical port (half of  113 ), a second uplink optical port (half of  113 ), N server downlink optical ports S 1   d  to SNd, and N server uplink optical ports S 1   u  to SNu. The downlink optical fiber d 1  to dK has a second end optically coupled to the second downlink optical port (half of  113 ). The uplink optical fiber u 1  to uK has a second end optically coupled to the second uplink optical port (half of  113 ). The SmartDistribuTOR module  111 - x  is configured to respectively direct the N downlink data communication optical signals and the N different wavelengths of continuous wave laser light received through the second downlink optical port (half of  113 ) to the N server downlink optical ports S 1   d  to SNd. The SmartDistribuTOR module  111 - x  is also configured to simultaneously direct N uplink data communication optical signals received through the N server uplink optical ports S 1   u  to SNu to the second uplink optical port (half of  113 ). 
     In the data communication system, each of N servers is optically connected to a respective one of the N server downlink optical ports S 1   d  to SNd of the SmartDistribuTOR module  111 - x  and to a respective one of the N server uplink optical ports S 1   u  to SNu of the SmartDistribuTOR module  111 - x . Each of the N servers includes a reverb module  601  having an optical input port  607 A and an optical output port  607 B. The optical input port  607 A of the reverb module  601  optically connected to the respective one of the N server downlink optical ports S 1   d  to SNd of the SmartDistribuTOR module  111 - x . The optical output port  607 B of the reverb module  601  optically connected to the respective one of the N server uplink optical ports S 1   u  to SNu of the SmartDistribuTOR module  111 - x . The reverb module  601  configured to convert a respective one of the N downlink data communication optical signals  704  received through the optical input port  607 A into a corresponding downlink data communication electrical signal for processing by the corresponding one of the N servers that includes the reverb module  601 . The reverb module  601  configured to convert an uplink data communication electrical signal provided by the corresponding one of the N servers that includes the reverb module into an uplink data communication optical signal  706  for transmission through the optical output port  607 B of the reverb module  601 . 
     In some embodiments, the reverb module  601  is configured to modulate a respective one of the N different wavelengths of continuous wave laser light  702  received through the optical input port  607 A to convert the uplink data communication electrical signal provided by the corresponding one of the N servers into the uplink data communication optical signal  706  for transmission through the optical output port  607 B of the reverb module  601 . 
     In some embodiments, the reverb module  601  includes the serializer/deserializer (SerDes) chip  605  configured to deserialize serial downlink data within the corresponding downlink data communication electrical signal that is converted from the respective one of the N downlink data communication optical signals  704  received through the optical input port  607 A to obtain parallel downlink data for processing by the corresponding one of the N servers that includes the reverb module  601 . In some embodiments, the SerDes chip  605  of the reverb module  601  is configured to serialize parallel uplink data provided by the corresponding one of the N servers that includes the reverb module  601  to generate the uplink data communication electrical signal prior to modulation of the respective one of the N different wavelengths of continuous wave laser light  702  received through the optical input port  607 A in order to convert the uplink data communication electrical signal into the uplink data communication optical signal  706  for transmission through the optical output port  607 B of the reverb module  601 . 
     In some embodiments, the TORminator module  107  includes the SerDes chip  201  connected to the rack switch  103 . The SerDes chip  201  is configured to serialize parallel downlink data received from the rack switch  103 . The SerDes chip  301  is also configured to deserialize serial uplink data within the N uplink data communication electrical signals for transmission to the rack switch  103 . Also, in some embodiments, the TORminator module  107  includes the laser chip  205  configured and connected to generate the N different wavelengths of continuous wave laser light. In some embodiments, the TORminator module  107  includes the optical amplifier (SOA) chip  207  configured and connected to amplify the N downlink data communication optical signals prior to being directed to the first downlink optical port (half of each of  109 - 1  to  109 -K). In some embodiments, the TORminator module  107  includes an optical amplifier (SOA) chip  209  configured and connected to amplify the N uplink data communication optical signals received through the first uplink optical port (half of each of  109 - 1  to  109 -K). 
     In some embodiments, the SmartDistribuTOR module  111 - x  is configured to direct the N downlink data communication optical signals received through the second downlink optical port (half of  113 ) into N separate optical channels Ch 1  to ChN, and the SmartDistribuTOR module  111 - x  is configured to direct the N different wavelengths of continuous wave laser light received through the second downlink optical port (half of  113 ) into the N separate optical channels Ch 1  to ChN, such that each of the N separate optical channels Ch 1  to ChN includes a different one of the N downlink data communication optical signals and a different one of the N different wavelengths of continuous wave laser light. The SmartDistribuTOR module  111 - x  is also configured to aggregate the N uplink data communication optical signals onto a single optical waveguide  117  for transmission through the second uplink optical port (half of  113 ). In some embodiments, the number N of separate optical channels Ch 1  to ChN is 8. 
     In some embodiments, the TORminator module  107  is configured and connected to receive a number (M) of downlink data communication electrical signals from the rack switch  103 , where M is an integer (K) multiple of N, i.e., M=(K)(N). The TORminator module  107  is configured to convert the M downlink data communication electrical signals into corresponding M downlink data communication optical signals. The M downlink data communication optical signals are distributed into K sets of N downlink data communication optical signals per set. Each of the N downlink data communication optical signals in a given one of the K sets has a different optical wavelength. The TORminator module  107  is configured to simultaneously direct the N downlink data communication optical signals in a given one of the K sets to a respective one of K downlink optical ports (half of each of  109 - 1  to  109 -K) of the TORminator module  107 . The TORminator module  107  is configured to simultaneously direct the N different wavelengths of continuous wave laser light to each of the K downlink optical ports (half of each of  109 - 1  to  109 -K) of the TORminator module  107 . The TORminator module  107  includes K uplink optical ports (half of each of  109 - 1  to  109 -K). The TORminator module  107  configured to convert N uplink data communication optical signals received through each of the K uplink optical ports (half of each of  109 - 1  to  109 -K) into N uplink data communication electrical signals to constitute M uplink data communication electrical signals. The TORminator module  107  configured to transmit the M uplink data communication electrical signals to the rack switch  103 . In some embodiments, K is 16, N is 8, and M is 128. However, in other embodiments, K is greater or less than 16, and/or N is greater or less than 8, and M equals N multiplied by K. 
     In some embodiments, each of K downlink optical fibers d 1  to dK has a first end optically coupled to a respective one of the K downlink optical ports (half of each of  109 - 1  to  109 -K) of the TORminator module  107 . And, each of K uplink optical fibers u 1  to uK has a first end optically coupled to a respective one of the K uplink optical ports (half of each of  109 - 1  to  109 -K) of the TORminator module  107 . Also, each of the K downlink optical fibers d 1  to dK has a second end optically coupled to a downlink optical port (half of  113 ) of a respective one of the K SmartDistribuTOR modules  111 - 1  to  111 -K. Also, each of the K uplink optical fibers u 1  to uK has a second end optically coupled to an uplink optical port (half of  113 ) of a respective one of the K SmartDistribuTOR modules  111 - 1  to  111 -K. Each of the K SmartDistribuTOR modules  111 - 1  to  111 -K has N server downlink optical ports S 1   d  to SNd and N server uplink optical ports S 1   u  to SNu. Each of the K SmartDistribuTOR modules  111 - 1  to  111 -K is configured to respectively direct the N downlink data communication optical signals and the N different wavelengths of continuous wave laser light received through its downlink optical port (half of  113 ) to its N server downlink optical ports S 1   d  to SNd. Each of the K SmartDistribuTOR modules  111 - 1  to  111 -K is configured to simultaneously direct N uplink data communication optical signals received through its N server uplink optical ports S 1   u  to SNu to its uplink optical port (half of  113 ). 
     Each of the N server downlink optical ports S 1   d  to SNd of a given one of the K SmartDistribuTOR modules  111 - 1  to  111 -K is optically connected to an optical input of a different server in a set of N servers. Each of the N server uplink optical ports S 1   u  to SNu of the given one of the K SmartDistribuTOR modules  111 - 1  to  111 -K is optically connected to an optical input of a different server in the set of N servers. In some embodiments, the given one of the K SmartDistribuTOR modules  111 - 1  to  111 -K and the set of N servers are disposed in a same rack. In some embodiments, the K SmartDistribuTOR modules  111 - 1  to  111 -K are collectively connected to optical inputs and optical outputs of M different servers. In some embodiments, the K SmartDistribuTOR modules  111 - 1  to  111 -K and the M different servers are distributed across K racks, with each of the K racks including a different one of the K SmartDistribuTOR modules  111 - 1  to  111 -K and a unique set of N servers of the M different servers. Also, the TORminator module  107  is disposed in one of the K racks. 
     In some embodiments, an optical multiplexer/demultiplexer module is disclosed. This optical multiplexer/demultiplexer module is referred to herein as the SmartDistribuTOR module  111 - x . The SmartDistribuTOR module  111 - x  includes a downlink optical port (half of  113 ), an uplink optical port (half of  113 ), a number (N) of server downlink optical ports S 1   d  to SNd, N server uplink optical ports S 1   u  to SNu, an optical demultiplexer  119 , and an optical multiplexer  121 . The optical demultiplexer  119  is configured to separate N downlink data communication optical signals received through the downlink optical port (half of  113 ) based on optical wavelength. The optical demultiplexer  119  is configured to respectively direct the N downlink data communication optical signals to the N server downlink optical ports S 1   d  to SNd. The optical demultiplexer  119  is also configured to separate N different wavelengths of continuous wave laser light received through the downlink optical port (half of  113 ) based on optical wavelength. The optical demultiplexer  119  configured to respectively direct the N different wavelengths of continuous wave laser light to the N server downlink optical ports S 1   d  to SNd. The optical multiplexer  121  is configured to aggregate N uplink data communication optical signals received through the N server uplink optical ports S 1   u  to SNu onto a single optical waveguide  117  optically coupled to the uplink optical port (half of  113 ). 
     Each of the N server downlink optical ports S 1   d  to SNd is optically coupled to a respective one of N servers, and each of the N server uplink optical ports S 1   u  to SNu is optically coupled to a respective one of the N servers. In some embodiments, the SmartDistribuTOR module  111 - x  and the N servers are disposed within a same rack. In some embodiments, the N different wavelengths of continuous wave laser light are generated by the laser chip  205  disposed separate from the SmartDistribuTOR module  111 - x . The SmartDistribuTOR module  111 - x  is configured to separate the N downlink data communication optical signals into N separate optical channels. The SmartDistribuTOR module  111 - x  is also configured to separate the N different wavelengths of continuous wave laser light into the N separate optical channels. In this manner, each of the N separate optical channels includes a different one of the N downlink data communication optical signals and a different one of the N different wavelengths of continuous wave laser light. In some embodiments, the value of N is 8. However, in other embodiments, the value of N is either greater than or less than 8. 
     In some embodiments, the SmartDistribuTOR module  111 - x  includes a downlink polarization control device  403  configured to split light received through downlink optical port (half of  113 ) into a first polarization of light and a second polarization of light. In some embodiments, the downlink polarization control device  403  includes a polarization splitting optical grating. In some embodiments, the downlink polarization control device  403  includes a polarization independent optical coupler having an optical output coupled to an optical input of a polarization splitter-rotator. In some embodiments, the downlink polarization control device  403  includes a thermally controlled Mach-Zehnder interferometer configured to combine the first polarization of light and the second polarization of light onto the single optical waveguide  405 . 
     In some embodiments, the optical demultiplexer  119  includes the tunable optical ring resonator filterbank  407  that includes N optical ring resonator filters  413 ( 1 ) to  413 (N). Each of the N optical ring resonator filters  413 ( 1 ) to  413 (N) includes at least one ring resonator  417 ( 1 ) to  417 (N) configured to drop one or more wavelengths of the N downlink data communication optical signals to a photodetector corresponding to the optical ring resonator filter  417 ( 1 ) to  417 (N). In some embodiments, the photodetector is integrated within the optical ring resonator filter  413 ( 1 ) to  413 (N). Additional description of photodetector integration within an optical ring resonator is provided in U.S. patent application Ser. No. 15/687,413, which is incorporated in its entirety herein by reference for all purposes. In some embodiments, the photodetector is configured and connected to operate as a sensor for wavelength lock within the optical ring resonator filter  413 ( 1 ) to  413 (N). In some embodiments, the optical demultiplexer  119  includes heaters  415 ( 1 ) to  415 (N) respectively embedded within the at least one ring resonator  417 ( 1 ) to  417 (N). The heaters  415 ( 1 ) to  415 (N) are electrically controllable to enable control of respective resonant wavelength of the at least one ring resonator  417 ( 1 ) to  417 (N). In some embodiments, the optical demultiplexer  119  includes embedded digital control loops  419 ( 1 ) to  419 (N) respectively connected to the heaters  415 ( 1 ) to  415 (N). A given embedded digital control loop  419 ( 1 ) to  419 (N) is configured to sense an amount of light that is absorbed within a given ring resonator  417 ( 1 ) to  417 (N). In this manner, the embedded digital control loops  419 ( 1 ) to  419 (N) are electrically connected to the photodetectors that are integrated within the optical ring resonator filters  413 ( 1 ) to  413 (N), respectively, in order to sense the amount of light that is absorbed within the ring resonators  417 ( 1 ) to  417 (N). 
     In some embodiments, the optical multiplexer  121  includes N optical waveguides  125 ( 1 ) to  125 (N) respectively optically coupled to the N server uplink optical ports S 1   u  to SNu. The optical multiplexer  121  includes N polarization control devices  503 ( 1 ) to  503 (N) optically coupled to the N optical waveguides  125 ( 1 ) to  125 (N). Each of the N polarization control devices  503 ( 1 ) to  503 (N) is configured to split light received through the N optical waveguides  125 ( 1 ) to  125 (N) from the corresponding N server uplink optical ports S 1   u  to SNu into a first polarization of light and a second polarization of light. In some embodiments, each of the N polarization control devices  503 ( 1 ) to  503 (N) includes a polarization splitting optical grating. In some embodiments, each of the N polarization control devices  503 ( 1 ) to  503 (N) includes a polarization independent optical coupler having an optical output coupled to an optical input of a polarization splitter-rotator. In some embodiments, each of the N polarization control devices  503 ( 1 ) to  503 (N) includes a thermally controlled Mach-Zehnder interferometer configured to combine the first polarization of light and the second polarization of light onto a single optical waveguide. The optical multiplexer  121  includes a tunable optical ring resonator filterbank  511  that includes N optical ring resonator filters  513 ( 1 ) to  513 (N). Each of the N optical ring resonator filters  513 ( 1 ) to  513 (N) includes at least one ring resonator  517 ( 1 ) to  517 (N) configured to drop one or more wavelengths of the N uplink data communication optical signals to a photodetector corresponding to the optical ring resonator filter  513 ( 1 ) to  513 (N). In some embodiments, the photodetector is integrated within the optical ring resonator filter  513 ( 1 ) to  513 (N). In some embodiments, the photodetector is configured and connected to operate as a sensor for wavelength lock within the optical ring resonator filter  513 ( 1 ) to  513 (N). 
     In some embodiments, the optical multiplexer  121  includes heaters  515 ( 1 ) to  515 (N) respectively embedded within the at least one ring resonator  517 ( 1 ) to  517 (N). The heaters  515 ( 1 ) to  515 (N) are electrically controllable to enable control of respective resonant wavelength of the at least one ring resonator  517 ( 1 ) to  517 (N). Embedded digital control loops  519 ( 1 ) to  519 (N) are respectively connected to the heaters  515 ( 1 ) to  515 (N). A given embedded digital control loop  519 ( 1 ) to  519 (N) is configured to sense an amount of light that is absorbed within a given ring resonator  517 ( 1 ) to  517 (N). In this manner, the embedded digital control loops  519 ( 1 ) to  519 (N) are electrically connected to the photodetectors that are integrated within the optical ring resonator filters  513 ( 1 ) to  513 (N), respectively, in order to sense the amount of light that is absorbed within the ring resonators  517 ( 1 ) to  517 (N). The tunable optical ring resonator filterbank  511  is configured to aggregate selected ones of the N uplink data communication optical signals onto the output optical waveguide  512 . The output optical waveguide  521  is optically coupled to the uplink optical port (half of  113 ) by way of the uplink optical waveguide  117 . 
     In some embodiments, an electro-optical interface module  601  is disclosed. The electro-optical interface module  601  is also referred to herein as the Reverb module  601 . The electro-optical interface module  601  includes an optical fiber interface configured to optically couple to the first optical fiber  607 A and the second optical fiber  607 B. The electro-optical interface module  601  includes the Reverb chip  603  (electronic-photonic chip) that includes a first optical coupler and a second optical coupler. The first optical coupler is configured and connected to receive light transmitted through the optical fiber interface from the first optical fiber  607 A. The second optical coupler is configured and connected to direct light through the optical fiber interface to the second optical fiber  607 B. In some embodiments, the Reverb chip  603  includes the downlink polarization control device  703  configured to split light received through the first optical coupler by way of the optical fiber  607 A into a first polarization of light and a second polarization of light. The Reverb chip  603  also includes the downlink data receiver device  709  configured and connected to receive light from the downlink polarization control device  703 . The downlink data receiver device  709  is configured and connected to filter downlink modulated light from the light received from the downlink polarization control device  703 , and convert the downlink modulated light into a downlink electrical data signal. The downlink data receiver device  709  is configured and connected to direct unmodulated continuous wave light received from the downlink polarization control device  703  to an optical output of the downlink data receiver device  709 . In some embodiments, the downlink polarization control device  703  includes a polarization splitting optical grating. In some embodiments, the downlink polarization control device  703  includes a polarization independent optical coupler having an optical output coupled to an optical input of a polarization splitter-rotator. In some embodiments, the downlink polarization control device  703  includes a thermally controlled Mach-Zehnder interferometer configured to combine the first polarization of light and the second polarization of light onto a single optical waveguide. 
     The Reverb chip  603  also includes the uplink data modulator device  711  configured and connected to receive the unmodulated continuous wave light from the optical output of the downlink polarization control device  709  by way of optical waveguide  705 . The uplink data modulator device  711  is configured and connected to imprint an uplink electrical data signal on the unmodulated continuous wave light to generate uplink modulated light. The uplink data modulator device  711  is configured and connected to direct the uplink modulated light to the second optical coupler of the Reverb chip  603 . 
     The Reverb chip  603  also includes the electrical input/output block  713  configured and connected to receive the downlink electrical data signal from the downlink data receiver device  709 , and direct the downlink electrical data signal to circuitry external to the Reverb chip  603 . The electrical input/output block  713  is configured and connected to receive the uplink electrical data signal from circuitry external to the Reverb chip  603  and direct the uplink electrical data signal to the uplink data modulator device  711 . 
     In some embodiments, the electronic components and photonic components of the Reverb chip  603  are integrated monolithically on a same die formed in a CMOS fabrication process. In some embodiments, the Reverb chip  603  includes electronic circuitry for controlling a polarization and a resonant wavelength of photonic components within the Reverb chip  603 . In some embodiments, the Reverb chip  603  includes non-retimed electronic circuitry including optical receivers and optical modulator drivers. In some embodiments, the Reverb chip  603  includes retimed electronic circuitry including a serializer circuit, a deserializer circuit, a clock generator, a phase-lock loop, and a clock-data-recovery loop. 
     In some embodiments, the downlink data receiver device  709  includes one or more resonant ring filters configured to drop one or more wavelengths of downlink modulated light to one or more photodetectors respectively corresponding to the one or more resonant ring filters. In some embodiments, the one or more photodetectors are respectively integrated in the one or more resonant ring filters. In some embodiments, the downlink data receiver device  709  includes one or more heaters respectively embedded within the one or more resonant ring filters, where the one or more heaters are electrically controllable to enable control of respective resonant wavelengths of the one or more resonant ring filters. In some embodiments, one or more embedded digital control loops are respectively connected to the one or more heaters, where a given embedded digital control loop is configured to sense an amount of light that is absorbed within a given resonant ring filter corresponding to a given heater connected to the given embedded digital control loop. In some embodiments, the one or more embedded digital control loops are implemented within the Reverb chip  603 . In some embodiments, the one or more embedded digital control loops are implemented within a CMOS chip different from the Reverb chip  603 . 
     In some embodiments, the uplink data modulator device  711  includes one or more resonant ring modulators respectively tuned to one or more wavelengths of the unmodulated continuous wave light received from the optical output of the downlink polarization control device  703 . In some embodiments, the uplink data receiver device  711  includes one or more heaters respectively embedded within the one or more resonant ring modulators, where the one or more heaters are electrically controllable to enable control of respective resonant wavelengths of the one or more resonant ring modulators. In some embodiments, the one or more embedded digital control loops are respectively connected to the one or more heaters, where a given embedded digital control loop is configured to sense an amount of light that is absorbed within a given resonant ring modulator corresponding to a given heater connected to the given embedded digital control loop. In some embodiments, the one or more embedded digital control loops are implemented within the Reverb chip  603 . In some embodiments, the one or more embedded digital control loops are implemented within a CMOS chip different from the Reverb chip  603 . 
       FIG. 10  shows a flowchart of a method for controlling data communication, in accordance with some embodiments. The method includes an operation  1001  for receiving a number (N) of downlink data communication electrical signals from a rack switch ( 103 ) at a TORminator module ( 107 ). The value of N is greater than one. The method also includes an operation  1003  for operating the TORminator module ( 107 ) to convert the N downlink data communication electrical signals into corresponding N downlink data communication optical signals. Each of the N downlink data communication optical signals has a different optical wavelength. The method also includes an operation  1005  for operating the TORminator module ( 107 ) to simultaneously direct the N downlink data communication optical signals to a first downlink optical port (half of each of  109 - 1  to  109 -K) of the TORminator module ( 107 ). The method also includes an operation  1007  for operating the TORminator module ( 107 ) to generate N different wavelengths of continuous wave laser light. In some embodiments, the method includes operating a laser chip ( 205 ) within the TORminator module ( 107 ) to generate the N different wavelengths of continuous wave laser light. In some embodiments, the value of N is 8. In some embodiments, the value of N is either greater than or less than 8. The method also includes an operation  1009  for operating the TORminator module to simultaneously direct the N different wavelengths of continuous wave laser light to the first downlink optical port (half of each of  109 - 1  to  109 -K) of the TORminator module ( 107 ). The method also includes an operation  1011  for operating the TORminator module ( 107 ) to receive N uplink data communication optical signals through a first uplink optical port (half of each of  109 - 1  to  109 -K) of the TORminator module ( 107 ). The method also includes an operation  1013  for operating the TORminator module ( 107 ) to convert the N uplink data communication optical signals into N uplink data communication electrical signals. The method also includes an operation  1015  for operating the TORminator module ( 107 ) to transmit the N uplink data communication electrical signals to the rack switch ( 103 ). 
     In some embodiments, the method of  FIG. 10  also includes operating a SmartDistribuTOR module ( 111 - x ) to simultaneously receive the N downlink data communication optical signals and the N different wavelengths of continuous wave laser light from the first downlink optical port of the TORminator module ( 107 ) through a single optical waveguide ( 115 ). The method also includes operating the SmartDistribuTOR module ( 111 - x ) to respectively direct the N downlink data communication optical signals and the N different wavelengths of continuous wave laser light to N servers, such that each of the N servers receives a different one of the N downlink data communication optical signals and a different one the N different wavelengths of continuous wave laser light. The method also includes operating the SmartDistribuTOR module ( 111 - x ) to receive N uplink data communication optical signals from the N servers. The method also includes operating the SmartDistribuTOR module ( 111 - x ) to simultaneously direct the N uplink data communication optical signals through a single optical waveguide to the TORminator module ( 107 ). 
     In some embodiments, the method of  FIG. 10  also includes operating N reverb modules ( 601 ) respectively disposed within the N servers to respectively receive the N downlink data communication optical signals and the N different wavelengths of continuous wave laser light from the SmartDistribuTOR module ( 111 - x ). The method also includes operating each of the N reverb modules ( 601 ) to convert the downlink data communication optical signal received from the SmartDistribuTOR module ( 111 - x ) into a corresponding data communication electrical signal for processing by the server in which the reverb module ( 601 ) is disposed. The method also includes operating each of the N reverb modules ( 601 ) to convert a data communication electrical signal provided by the server in which the reverb module ( 601 ) is disposed into an uplink data communication optical signal. The method also includes operating each of the N reverb modules ( 601 ) to transmit the uplink data communication optical signal to the SmartDistribuTOR module ( 111 - x ). Each of the N reverb modules ( 601 ) modulates a respective one of the N different wavelengths of continuous wave laser light to convert the data communication electrical signal provided by the server in which the reverb module ( 601 ) is disposed into the uplink data communication optical signal. 
     In some embodiments, the method of  FIG. 10  includes operating the TORminator module ( 107 ) to receive a number (M) of downlink data communication electrical signals from the rack switch ( 103 ), wherein M is an integer (K) multiple of N, i.e., M=(K)(N), and where the previously mentioned N downlink data communication electrical signals are included in the M downlink data communication electrical signals. In some embodiments, K is 16, N is 8, and M is 128. However, in other embodiments, K is greater or less than 16, and/or N is greater or less than 8, and M equals N multiplied by K. The method also includes operating the TORminator module ( 107 ) to convert the M downlink data communication electrical signals into corresponding M downlink data communication optical signals. The method also includes operating the TORminator module ( 107 ) to distribute the M downlink data communication optical signals into K sets of N downlink data communication optical signals per set. Each of the N downlink data communication optical signals in a given one of the K sets has a different optical wavelength. The method also includes operating the TORminator module ( 107 ) to simultaneously direct the N downlink data communication optical signals in a given one of the K sets to a respective one of K downlink optical ports of the TORminator module ( 107 ). The previously mentioned first downlink optical port of the TORminator module ( 107 ) is a first of the K downlink optical ports of the TORminator module ( 107 ). The method also includes operating the TORminator module ( 107 ) to simultaneously direct the N different wavelengths of continuous wave laser light to each of the K downlink optical ports of the TORminator module ( 107 ). The method also includes operating the TORminator module ( 107 ) to receive N uplink data communication optical signals through each of K uplink optical ports. The previously mentioned first uplink optical port of the TORminator module ( 107 ) is a first of the K uplink optical ports of the TORminator module ( 107 ). The method also includes operating the TORminator module ( 107 ) to convert the N uplink data communication optical signals received through each of the K uplink optical ports into N uplink data communication electrical signals to constitute M uplink data communication electrical signals. The method also includes operating the TORminator module ( 107 ) to transmit the M uplink data communication electrical signals to the rack switch ( 103 ). 
     In some embodiments, the method also includes operating each of K SmartDistribuTOR modules ( 111 - 1  to  111 -K) to receive the N downlink data communication optical signals in a corresponding one of the K sets from the TORminator module ( 107 ). The method also includes operating each of the K SmartDistribuTOR modules ( 111 - 1  to  111 -K) to receive the N different wavelengths of continuous wave laser light from the TORminator module ( 107 ). The method also includes operating each of the K SmartDistribuTOR modules ( 111 - 1  to  111 -K) to separate the N downlink data communication optical signals and respectively transmit the N downlink data communication optical signals to N servers. The method also includes operating each of the K SmartDistribuTOR modules ( 111 - 1  to  111 -K) to respectively transmit the N different wavelengths of continuous wave laser light to the N servers. 
     The method also includes operating each of the K SmartDistribuTOR modules ( 111 - 1  to  111 -K) to receive N uplink data communication optical signals from the N servers. The method also includes operating each of the K SmartDistribuTOR modules ( 111 - 1  to  111 -K) to aggregate the N uplink data communication optical signals onto a single optical waveguide and transmit the N uplink data communication optical signals through the single optical waveguide to the TORminator module ( 107 ), such that the TORminator module ( 107 ) collectively receives M uplink data communication optical signals from the K SmartDistribuTOR modules ( 111 - 1  to  111 -K). The method also includes operating the TORminator module ( 107 ) to convert the M uplink data communication optical signals into M uplink data communication electrical signals. The method also includes operating the TORminator module ( 107 ) to transmit the M uplink data communication electrical signals to the rack switch ( 103 ). 
       FIG. 11  shows a flowchart of a method for operating an optical multiplexer/demultiplexer module, in accordance with some embodiments. The optical multiplexer/demultiplexer module of the method of  FIG. 11  is the SmartDistribuTOR module ( 111 - x ) disclosed herein. The method includes an operation  1101  for receiving a number (N) of downlink data communication optical signals through a downlink optical port (half of  113 ). The method also includes an operation  1103  for separating the N downlink data communication optical signals into N separate optical channels. The method also includes an operation  1105  for receiving N different wavelengths of continuous wave laser light through the downlink optical port (half of  113 ). The method also includes an operation  1107  for separating the N different wavelengths of continuous wave laser light into the N separate optical channels. The method also includes an operation  1109  for respectively directing the N separate optical channels to N server downlink optical ports (S 1   d  to SNd). The method also includes an operation  1111  for respectively receiving N uplink data communication optical signals through the N server uplink optical ports (S 1   u  to SNu). The method also includes an operation  1113  for aggregating the N uplink data communication optical signals onto a single optical waveguide ( 117 ) optically coupled to an uplink optical port (half of  113 ). 
     In some embodiments, the method includes transmitting the N downlink data communication optical signals through a downlink polarization control device ( 403 ) to split each of the N downlink data communication optical signals into a first polarization of light and a second polarization of light. In some embodiments, the operation  1103  for separating the N downlink data communication optical signals into N separate optical channels is performed by operating a tunable optical ring resonator filterbank ( 407 ) that includes N optical ring resonator filters ( 413 ( 1 )- 413 (N)). Each of the N optical ring resonator filters ( 413 ( 1 )- 413 (N)) includes at least one ring resonator ( 417 ( 1 )- 417 (N)) operating to drop one or more wavelengths of the N downlink data communication optical signals to a photodetector corresponding to the optical ring resonator filter ( 413 ( 1 )- 413 (N)). 
     In some embodiments, operating the tunable optical ring resonator filterbank ( 407 ) includes operating heaters ( 415 ( 1 )- 415 (N)) respectively embedded within the at least one ring resonator ( 417 ( 1 )- 417 (N)) to control a respective resonant wavelength of the at least one ring resonator ( 417 ( 1 )- 417 (N)). In some embodiments, the method includes respectively transmitting the N uplink data communication optical signals through N uplink polarization control devices ( 503 ( 1 )- 503 (N)) to split each of the N uplink data communication optical signals into a first polarization of light and a second polarization of light. The method also includes aggregating the N uplink data communication optical signals onto the single optical waveguide ( 117 ) includes operating a tunable optical ring resonator filterbank ( 511 ) that includes N optical ring resonator filters ( 513 ( 1 )- 513 (N)). Each of the N optical ring resonator filters ( 513 ( 1 )- 513 (N)) includes at least one ring resonator ( 517 ( 1 )- 517 (N)) operating to drop one or more wavelengths of the N uplink data communication optical signals to a photodetector corresponding to the optical ring resonator filter ( 513 ( 1 )- 513 (N)). In some embodiments, operating the tunable optical ring resonator filterbank ( 511 ) includes operating heaters ( 515 ( 1 )- 515 (N)) respectively embedded within the at least one ring resonator ( 517 ( 1 )- 517 (N)) to control a respective resonant wavelength of the at least one ring resonator ( 517 ( 1 )- 517 (N)). 
       FIG. 12  shows a flowchart of a method for operating an electro-optical interface of a server, in accordance with some embodiments. The electro-optical interface of the server is the Reverb module  601  disclosed herein. The method includes an operation  1201  for receiving downlink light through a first optical coupler, where the downlink light includes downlink modulated light of a first wavelength and unmodulated continuous wave light of a second wavelength. The method also includes an operation  1203  for filtering the downlink modulated light from the downlink light. In some embodiments, the method also includes splitting the downlink light into a first polarization of light and a second polarization of light prior to filtering the downlink modulated light from the downlink light in operation  1203 . The method also includes an operation  1205  for converting the downlink modulated light into a downlink electrical data signal. The method also includes an operation  1207  for transmitting the downlink electrical data signal to processing circuitry. The method also includes an operation  1209  for imprinting an uplink electrical data signal on the unmodulated continuous wave light to generate uplink modulated light. The method also includes an operation  1211  for transmitting the uplink modulated light through the a second optical coupler. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention. 
     Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the invention description. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the described embodiments.