Patent Description:
Some embodiments described herein relate generally to methods and apparatus for remote management of an optical transceiver. In particular, but not by way of limitation, some embodiments described herein relate to methods and apparatus for remote management of an optical transceiver via an embedded communication channel (ECC).

Optical transceivers used in WDM systems transmit and receive data by combining a number of different optical channels or signals at different wavelengths onto a single optical fiber or a set of optical fibers. Each wavelength can be associated with a different WDM channel. Light for these WDM channels can be modulated to produce optical signals at different wavelengths to carry data separately.

In an optical network with a number of optical transceivers, each optical transceiver can have its status monitored and troubleshooting can be performed when an optical transceiver fails. Known methods typically provide information regarding the health of an optical transceiver locally. In other words, operational status of a given optical transceiver, such as loss of light, receiving optical power, and faults, are only available at such optical transceiver. Other known methods that use test equipment to examine the operational status of optical transceivers typically involve interrupting the connection to the optical transceivers to retrieve such information.

US<CIT> discloses a signal transmitting device having two transceivers and a controller configured to control a transmission level of signal light in accordance with a reception level of probe light which is input from the receiver over a medium in the transmission line.

Accordingly, a need exists for methods and apparatus to remotely monitor and control an optical transceiver in an optical network without local interruption.

Particular aspects and embodiments are set out in the appended claims.

In some embodiments, an apparatus includes a first optical transceiver. The first optical transceiver includes a set of optical transmitters, an optical multiplexer operatively coupled to the set of optical transmitters, and a variable optical attenuator operatively coupled to the optical multiplexer. The variable optical attenuator is configured to receive a control signal from a controller of the first optical transceiver and modulate a signal representing control information with an output from the optical multiplexer. The control information is associated with the control signal and for a second optical transceiver operatively coupled to the first optical transceiver.

In some embodiments, the apparatus further includes a set of optical receivers, an optical demultiplexer, an optical detector, and an optical tap. The optical demultiplexer is operatively coupled to the set of optical receivers. The optical tap is operatively coupled to the optical demultiplexer and the optical detector. The optical tap is configured to receive a portion of an optical signal received from the second optical transceiver. The optical detector is configured to detect the portion of the optical signal to produce a detected signal. The controller is configured to decode the detected signal to extract an encoded signal from the optical signal.

As used in this specification, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, the term "an optical transceiver" is intended to mean a single optical transceiver or multiple optical transceivers.

<FIG> is a block diagram of a master optical transceiver and a slave optical transceiver, according to an embodiment. The master optical transceiver <NUM> can be any high data rate optical transceiver such as, for example, an on-off-keyed (OOK) transmitter, an optical M-ary quadrature amplitude modulation (M-QAM) transmitter, an optical M-ary pulse amplitude modulation (mPAM) transmitter, a polarization multiplexed (PM) M-QAM transmitter, and/or the like. The master optical transceiver <NUM> includes transmit (Tx) electrical functions (not shown in <FIG>), receive (Rx) electrical functions (not shown in <FIG>), transmit (Tx) optical functions <NUM>, receive (Rx) optical functions <NUM>, and a controller <NUM>. The Tx electrical functions are operatively coupled to the Tx optical functions <NUM>. The Rx electrical functions are operatively coupled to the Rx optical functions <NUM>. The Tx electrical functions, the Rx electrical functions, the Tx optical functions <NUM>, and the Rx optical functions <NUM> are operatively coupled to the controller <NUM>. Each of the Tx electrical functions, the Tx optical functions <NUM>, and the controller <NUM> can send signals to and/or receive signals from each other. Similarly, each of the Rx electrical functions, the Rx optical functions <NUM>, and the controller <NUM> can send signals to and/or receive signals from each other. Although the Tx electrical functions, the Tx optical functions <NUM>, and the controller <NUM> are discussed in connection with in <FIG> as being separate, each needs not be physically separate from the other two. Stated differently, the Tx electrical functions and/or the Tx optical functions <NUM> and/or the controller <NUM> may be co-located and/or integrated together within a single module, subsystem or component. Similarly, although the Rx electrical functions, the Rx optical functions <NUM>, and the controller <NUM> are discussed in connection with in <FIG> as being separate, each needs not be physically separate from the other two. Stated differently, the Rx electrical functions and/or the Rx optical functions <NUM> and/or the controller <NUM> may be co-located and/or integrated together within a single module, subsystem or component.

The slave optical transceiver <NUM> is substantially the same in physical structures and functionality as the master optical transceiver <NUM>. The slave optical transceiver <NUM> can be any high data rate optical transceiver such as, for example, an on-off-keyed (OOK) transmitter, an optical M-ary quadrature amplitude modulation (M-QAM) transmitter, an optical M-ary pulse amplitude modulation (mPAM) transmitter, a polarization multiplexed (PM) M-QAM transmitter, and/or the like. The slave optical transceiver <NUM> includes transmit (Tx) electrical functions (not shown in <FIG>), receive (Rx) electrical functions (not shown in <FIG>), transmit (Tx) optical functions <NUM>, receive (Rx) optical functions <NUM>, and a controller <NUM>.

The Tx electrical functions of the master optical transceiver <NUM> generate and/or process electrical signals sent to the Tx optical functions <NUM> of the master optical transceiver <NUM>. The Tx electrical functions are the electronic components of the master optical transceiver <NUM>. For example, the Tx electrical functions can include a set of electrical transmitters that transmit a set of electrical signals from a set of electrical channels. The set of electrical signals are transmitted to the optical functions <NUM> and converted to optical signals. An example of the Tx electrical functions is discussed in co-pending <CIT>, and entitled "Method and Apparatus for Self Healing of an Optical Transceiver in a Wavelength Division Multiplexing (WDM) System".

The Tx optical functions <NUM> are the photonic components of the master optical transceiver <NUM>. For example, the Tx optical functions <NUM> may include a set of optical transmitters <NUM>(<NUM>) - <NUM>(n), and an optical multiplexer (MUX) <NUM> operatively coupled to the set of optical transmitters <NUM>(<NUM>) - <NUM>(n), and a variable optical attenuator <NUM> operatively coupled to the optical multiplexer.

Each optical transmitter <NUM>(<NUM>) - <NUM>(n) from the set of optical transmitters in the Tx optical functions <NUM> can transmit at a unique wavelength from a set of wavelengths. Similarly, each optical receiver from the set of optical receivers <NUM>(<NUM>)-<NUM>(n) in the master optical transceiver <NUM> can receive at a unique wavelength from a set of wavelengths.

The optical multiplexer <NUM> is a hardware device that can, for example, multiplex and route different channels of light or optical signals into or out of, for example, a single mode fiber (SMF). The optical multiplexer <NUM> can multiplex the optical signals generated and/or transmitted by the different optical transmitters from the set of optical transmitters <NUM>(<NUM>) - <NUM>(n) onto a single optical fiber (or multiple optical fibers) <NUM>. and send the different channels of optical signals to the variable optical attenuator (VOA) <NUM>. When multiplexed onto multiple optical fibers, two or more optical signals can be multiplexed by the optical multiplexer <NUM> onto each of the multiple optical fibers.

The variable optical attenuator (VOA) <NUM> includes, for example, a Mach-Zehnder Modulator (MZM), a micro-electromechanical system (MEMS), or other technology that varies an optical signal amplitude as a function of an applied electrical signal. The VOA <NUM> modulates the optical signal from each optical channel received from the MUX <NUM> such that the amplitude of the optical signal from each optical channel is varied based on an electrical signal input. The VOA <NUM> can send the optical signals to a single mode fiber <NUM> (or multiple optical fibers). The different channels of optical signals can be sent to the slave optical transceiver <NUM> via such single mode fiber.

Referring to the embodiment of the master optical transceiver <NUM> shown in <FIG>, the master optical transceiver <NUM> further includes Rx optical functions <NUM>. As discussed in detail herein, the Tx optical functions <NUM> can receive optical signals from the Tx electrical functions (not shown in <FIG>) and send optical signals to the slave optical transceiver <NUM>. The Rx optical functions can receive optical signals from the slave optical transceiver <NUM> and send optical signals to the Rx electrical functions (not shown in <FIG>). Additionally, the optical functions <NUM>/<NUM> can also send signals to and/or receive signals from the controller <NUM>.

The Rx optical functions <NUM> include the photonic components of the master optical transceiver <NUM>. The Rx optical functions <NUM> may include a set of optical receivers <NUM>(<NUM>) - <NUM>(n), and an optical demultiplexer (DMUX) <NUM> operatively coupled to the set of optical receivers <NUM>(<NUM>) - <NUM>(n). The Rx optical functions <NUM> also include an optical tap <NUM> and an optical detector <NUM>. Each optical receiver from the set of optical receivers <NUM>(<NUM>) - <NUM>(n) in the Rx optical functions <NUM> can receive at a unique wavelength from a set of wavelengths.

The optical demultiplexer <NUM> is a hardware device that can, for example, demultiplex and route different channels of light or optical signals received from, for example, a single mode fiber (SMF). The optical demultiplexer <NUM> can demultiplex the optical signals received from a single optical fiber <NUM> (or multiple optical fibers) (or the optical tap <NUM>), and can transmit to different optical receivers from the set of optical receivers <NUM>(<NUM>) - <NUM>(n).

The optical tap <NUM> is a hardware device that can, for example, divert a portion of the one of more of the optical signals received from the optical fiber <NUM> to the optical detector <NUM>. The optical detector <NUM> can detect the received portion(s) of the optical signal(s) from the optical tap <NUM>. The optical detector <NUM> can include, for example, a monitor photodiode (MPD). The optical signal from the MPD can be further filtered by a low pass filter (LPF) (not shown in <FIG>), amplified by an amplifier, (not shown in <FIG>) and sent to the controller <NUM>.

The controller <NUM> sends and/or receives control signals including control information to other components in the master optical transceiver <NUM>. Although <FIG> shows the controller <NUM> to be separate from the Tx optical functions <NUM> and the Rx optical functions <NUM>, the controller <NUM> may be physically co-located with the electrical functions (not shown in <FIG>), the Tx optical functions <NUM>, and/or the Rx optical functions <NUM>. For example, in some configurations, the controller <NUM> may be physically disposed within an integrated circuit package co-packaged with the set of electrical transmitters, the set of electrical receivers, switches (not shown in <FIG>), the set of optical transmitters <NUM>, the set of optical receivers <NUM>, the optical multiplexer <NUM> and/or the optical demultiplexer <NUM>.

In some embodiments, the controller <NUM> includes a processor <NUM>, a memory <NUM>, a decoder <NUM> and an encoder <NUM>. The memory <NUM> can be, for example, a random-access memory (RAM) (e.g., a dynamic RAM, a static RAM), a flash memory, a removable memory, a database and/or so forth. In some implementations, the memory <NUM> can include or implement, for example, a database, process, application, and/or some other software modules (stored in memory <NUM> and/or executing in processor <NUM>) or hardware modules configured to execute remote management and control process and/or one or more associated methods for the remote management and control of the optical transceiver <NUM>. In such embodiments, instructions for executing the remote management and control of optical transceivers process and/or the associated methods can be stored within the memory <NUM> and executed at the processor <NUM>.

The processor <NUM> can include, for example, a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC), a digital signal processor (DSP), and/or the like. The processor <NUM> can be configured to, for example, write data into and read data from the memory <NUM>, and execute the instructions stored within the memory <NUM>. The processor <NUM> can also be configured to execute and/or control, for example, the operations of the optical transmitters <NUM>(<NUM>)-<NUM>(n), switches (not shown in <FIG>), the set of optical receivers <NUM>(<NUM>) - <NUM>(n), the variable optical attenuator (VOA) <NUM>, the optical tap <NUM>, and/or the optical detector <NUM>. In some implementations, based on the methods or processes stored within the memory <NUM>, the processor <NUM> can be configured to execute the remote management and control of optical transceivers process, as described in <FIG>.

The encoder <NUM> and the decoder <NUM> are modules operatively coupled to each other and to the remaining component(s) (e.g., processor <NUM>, memory <NUM>) of the controller <NUM>. The encoder <NUM> and the decoder <NUM> can be any combination of hardware and/or software (stored and/or executing in hardware) capable of performing one or more specific functions associated with that module. In some embodiments, the encoder <NUM> and the decoder <NUM> can include, for example, a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC), a digital signal processor (DSP), and/or the like.

During transmission of optical signals, the encoder <NUM> applies a low frequency (e.g., <NUM>) electrical signal to the VOA <NUM> to modulate the amplitude of the optical signals. The applied low frequency electrical signal carries control information. The control information can include, for example, an identifier (or an address) of a slave optical transceivers <NUM> (or identifiers/addresses of multiple slave optical transceivers); an instruction to monitor, control, identify, or configure the slave optical transceiver <NUM> (or multiple slave optical transceivers); activate or deactivate an optical channel from the slave optical transceiver <NUM>; update a software program of the slave optical transceiver <NUM>; monitor optical signals received at the slave optical transceiver <NUM>; and/or the like. Such control information can be contained in the magnitude, phase, or both of the low frequency electrical signal. The frequency of the electrical signal carrying the control information is lower than the frequencies of the optical signals (containing the data information) such that the information carried by (or modulated onto) the optical signals are not affected by the low frequency electrical signal. The low frequency electrical signal can be applied to one or multiple optical signals.

During receiving of the optical signals, the optical Rx signals are tapped by the optical tap <NUM> and a portion of the optical Rx signals are detected in the optical detector <NUM>. The optical detector <NUM> can send the optical signals to the decoder <NUM>. The decoder <NUM> extracts the embedded control information and the controller <NUM> analyzes the control information to manage, control, or configure the master optical transceiver <NUM>. Similar to the control information transmitted from the master optical transceiver <NUM> to the slave optical transceiver <NUM>, the control information received at the master optical transceiver <NUM> from the slave optical transceiver <NUM> can include, for example, an identifier (or an address) of a master optical transceiver (or identifiers/addresses of multiple master optical transceivers); an instruction to monitor, control, identify , or configure the master optical transceiver <NUM> (or multiple master optical transceivers); activate or deactivate an optical channel from the master optical transceiver <NUM>; update a software program of the master optical transceiver <NUM>; monitor optical signals received at the master optical transceiver <NUM>; and/or the like. The control information analysis can be implemented by a processor and/or a memory of the controller <NUM> (e.g., processor <NUM> and/or memory <NUM>).

As discussed above, the slave optical transceiver <NUM> is substantially the same in physical structures and functionality as the master optical transceiver <NUM>. The slave optical transceiver <NUM> is communicatively coupled to the master optical transceiver <NUM>. In one implementation, the slave optical transceiver <NUM> can be disposed in the same optical network as the master optical transceiver <NUM>. In another implementation, the slave optical transceiver <NUM> can also be disposed in a different optical network as the master optical transceiver <NUM>. The slave optical transceiver <NUM> includes a receive (Rx) optical functions <NUM>, a transmit (Tx) optical functions <NUM>, and a controller <NUM>. The Rx optical functions <NUM> are substantially the same in physical structures and functionality as the Rx optical functions <NUM> of the master optical transceiver <NUM>. The Tx optical functions <NUM> are substantially the same in physical structures and functionality as the Tx optical functions <NUM> of the master optical transceiver <NUM>. The controller <NUM> is substantially the same in physical structures and functionality as the controller <NUM> of the master optical transceiver <NUM>.

In use, the optical signals from each optical transmitter from the set of optical transmitters <NUM>(<NUM>) - <NUM>(n) are multiplexed by the multiplexer <NUM> and transmitted to the VOA <NUM>. The encoder <NUM> of the master optical transceiver <NUM> sends a low frequency electrical signal carrying control information to the VOA <NUM>. The VOA <NUM> modulates the optical signals based on the low frequency electrical signal and produces modulated optical signals carrying data information and control information. The modulated optical signals are transmitted via the optical fiber <NUM> to the optical tap <NUM> of the slave optical transceiver <NUM>. The modulated optical signals then tapped by the optical tap <NUM> of the slave optical transceiver <NUM> and a portion of the modulated optical signals are detected in the optical detector <NUM>. The optical detector <NUM> can send the modulated optical signals to the decoder <NUM> of the slave optical transceiver <NUM>. The decoder <NUM> extracts the embedded control information and the controller <NUM> analyzes the control information to manage, control, or configure the slave optical transceiver <NUM>.

Similarly, the Tx optical functions <NUM> of the slave optical transceiver <NUM> can transmit optical signals to the Rx optical functions <NUM> of the master optical transceiver <NUM>. The encoder <NUM> of the slave optical transceiver <NUM> sends a low frequency electrical signal carrying control information to the VOA <NUM>. The VOA <NUM> modulates the optical signals based on the low frequency electrical signal and produces modulated optical signals carrying data information and control information. The modulated optical signals are transmitted via the optical fiber <NUM> to the optical tap <NUM> of the master optical transceiver <NUM>. The modulated optical signals then tapped by the optical tap <NUM> of the master optical transceiver <NUM> and a portion of the modulated optical signals are detected in the optical detector <NUM>. The optical detector <NUM> can send the modulated optical signals to the decoder <NUM> of the master optical transceiver <NUM>. The decoder <NUM> extracts the embedded control information and the controller <NUM> analyzes the control information to manage, control, or configure the master optical transceiver <NUM>.

For example, when the controller <NUM> of the master optical transceiver <NUM> detects a failure associated with an optical transmitter at the master optical transceiver <NUM>, the encoder <NUM> sends a low frequency electrical signal carrying such failure message and/or corresponding control information to the VOA <NUM> of the master optical transceiver <NUM>. The VOA <NUM> modulates optical signals based on the low frequency electrical signal and produces modulated optical signals carrying data information and control information. The modulated optical signals are transmitted to the slave optical transceiver <NUM>. The decoder <NUM> of the slave optical transceiver <NUM> extracts a portion(s) of the embedded control information and the controller <NUM> analyzes the control information. The controller <NUM> sends a signal to activate a spare optical receiver at the slave optical transceiver <NUM> based on the control information such that the optical signal(s) transmitted from the failed optical transmitter at the master optical transceiver <NUM> can be received at the spare optical receiver at the slave optical transceiver <NUM>. Details of such implementation are discussed in co-pending <CIT>, and entitled "Method and Apparatus for Self Healing of an Optical Transceiver in a Wavelength Division Multiplexing (WDM) System".

For another example, the controller <NUM> of the master optical transceiver <NUM> can request status information of the slave optical transceiver <NUM> from the controller <NUM> of the slave optical transceiver <NUM>. A control signal containing the request for the status information can be transmitted via modulated optical signals to the slave optical transceiver <NUM> and such status information can be returned via modulated optical signals to the controller <NUM> of the master optical transceiver <NUM>.

In one configuration, the control information can be encoded onto multiple optical channels simultaneously at a transmit side of an optical transceiver. The control information can then be decoded from multiple optical channels at a receive side of another optical transceiver. In another configuration, the control information is encoded to a single optical channel at a transmit side of an optical transceiver before the optical signals from the set of optical transmitters are multiplexed at a multiplexer. The control information can then be decoded from a single optical channel at a receive side of another optical transceiver.

In some embodiments, the control signal can be initiated by the controller of the master optical transceiver via a synchronous serial interface such as SPI/MDIO/I2C or asynchronous serial interface via a universal asynchronous receiver/transmitter (UART). The local synchronous/asynchronous interface can be located at the controller.

In one embodiment, each optical transmitter from the set of optical transmitters is configured to send an optical signal having data information associated with a channel from a set of channels. The set of channels is, for example, a set of parallel signal mode (PSM) channels. Each optical transmitter is uniquely associated with a PSM channel from the set of PSM channels. In such embodiment, the VOA <NUM> is located between the set of optical transmitters and an optical splitter that splits the laser power to a set of optical modulators. The control information is encoded on one re more PSM channels. In such embodiment, the optical transceiver may not need an optical multiplexer.

In one embodiment, the optical signals transmitted/received from the set of optical transmitters/receivers can be directly modulated internally by the set of optical transmitters/receivers. In another embodiment, the optical signals transmitted/received from the set of optical transmitters/receivers can be externally modulated by a set of optical modulators.

<FIG> is a block diagram of a controller in a master optical transceiver and a controller in a slave optical transceiver, according to an embodiment. In monitoring the operational health and the connectivity of an optical transceiver network including multiple optical transceivers, remote configuration and management of each optical transceiver without the requirement of local management is beneficial. A virtual bridge (i.e., a communication channel) between a host optical transceiver (also referred herein to as a master optical transceiver) and a remote optical transceiver (also referred herein to as a slave optical transceiver) can be configured to facilitate such remote management and configuration. A communication channel can be out of band (e.g., over the internet, over separate connections, or over a separate network), in band (e.g., using reserved bits in data framing of at least one of the optical channels), or via an embedded communication channel (ECC). The ECC information can be transmitted via the same fiber as the data information and is independent of the data information. To limit the amount of traffic flow across the ECC, a master optical transceiver can be configured to retrieve, for example, up to <NUM> bytes of status from a slave optical transceiver. In one implementation, the ECC is implemented as a point-to-point connection at, for example, <NUM> kbps.

As shown in <FIG>, a network element A <NUM> (also referred herein to as a master network element) includes an optical transceiver <NUM>. The optical transceiver <NUM> is operatively coupled to a host electrical interface(s) <NUM>. The optical transceiver <NUM> includes an embedded communication channel (ECC) encoder <NUM>, an ECC decoder <NUM>, and a 12C/MDIO master/slave module <NUM>. The 12C/MDIO master/slave module <NUM> receives management/control information via a management input/output (I/O) interface <NUM>. A network element B <NUM> (also referred herein to as a slave network element), which is communicatively coupled to the network element A <NUM>, includes an optical transceiver <NUM>. The optical transceiver <NUM> is substantially similar in physical structures and functionality to the optical transceiver <NUM>. The 12C/MDIO master/slave module <NUM> of the optical transceiver <NUM> transmits/receives management/control information via a management I/O interface (not shown in <FIG>) to/from a set of optical/electrical physical medium dependent sublayer (PMD) devices <NUM>(<NUM>) - <NUM>(n). The specifications for PMD include, for example, <NUM> gigabit Ethernet, fast Ethernet, gigabit Ethernet, and/or the like. A specification of 10GBASE-E can be used for single mode fiber operations, which operates in the <NUM> band allowing for distances of up to <NUM> to be reached. In such embodiment, the control information encoded by the optical transceiver <NUM> of the master network element A <NUM> is transmitted to the slave network element B <NUM>. The optical transceiver <NUM> of the slave network element <NUM> decodes the control information and conveys to other devices (such as the PMDs <NUM>(<NUM>) - <NUM>(n)) at the slave network element B <NUM>. Control information can also be transmitted from the PMDs <NUM>(<NUM>) - <NUM>(n), through the optical transceiver <NUM> of the slave network element B <NUM>, to the optical transceiver <NUM> of the master network element A <NUM>, thereby closing the communication link for the control information.

For example, a master optical transceiver can communicate with a set of Quad Small Form-factor Pluggable (QSFP) modules connected to a slave optical transceiver. The master optical transceiver has one slave 12C interface and two master 12C interfaces in addition to <NUM> general purpose input/outputs (GPIOs) that are configured to control and communicate status with a slave optical transceiver (or multiple slave optical transceivers). The slave 12C interface is used for the host to communicate to the master optical transceiver. One of the master 12C interfaces is shared to communicate to all of the QSFPs. <NUM> of the GPIOs are configured to act as ModSelL. Another <NUM> GPIOs are configured to receive indication of the module needing attention via the IntL lines. For the more static indications/control such as ModPrsL and Reset, the second master 12C is connected to an 12C port expander.

<FIG> is a flowchart illustrating a method of transmitting control information from an optical transceiver, according to an embodiment. This method <NUM> can be implemented at a processor and/or a memory (e.g., processor <NUM> or memory <NUM> as discussed in <FIG>) of a controller of an optical transceiver (also referred herein to as a master optical transceiver). The method includes receiving a control signal from a controller of a first optical transceiver. As discussed above, a variable optical attenuator (VOA) of the first optical transceiver receives a low frequency (e.g., <NUM>) electrical signal at <NUM> to modulate amplitudes of optical signals being transmitted within and by the first optical transceiver at <NUM>. The low frequency electrical signal represents, for example, control information including an identifier of a slave optical transceivers (or identifiers of multiple slave optical transceivers); an instruction to monitor, control, or configure a slave optical transceiver (or multiple slave optical transceivers); activate or deactivate an optical channel (or multiple optical channels) from the slave optical transceiver; update a software program of the slave optical transceiver; monitor optical signals received at the slave optical transceiver; and/or the like. Such control information can be contained in the magnitude, phase, or both of the low frequency electrical signal. The frequency of the electrical signal carrying the control information is lower than the frequencies of the optical signals (containing the data information) such that the transmission of the optical signals are not affected by the low frequency electrical signal.

At <NUM>, the VOA forms a modulated signal based on the received control signal (i.e., the low frequency electrical signal). At <NUM>, the master optical transceiver sends to a second optical transceiver (also referred herein to as a slave optical transceiver) a signal having data information and the modulated signal representing the control information. A decoder (such as the decoder <NUM> discussed in <FIG>) at the second optical transceiver decodes the modulated signal and extracts the control information transmitted from the first optical transceiver. A controller of the second optical transceiver sends commands to other components of the second optical transceiver to modify its operation based on the modulated signal.

<FIG> is a flowchart illustrating a method of receiving control information at an optical transceiver, according to an embodiment. This method <NUM> can be implemented at a processor and/or a memory (e.g., processor <NUM> or memory <NUM> as discussed in <FIG>) of a controller of an optical transceiver. The method includes, at <NUM>, receiving at an optical tap of a first optical transceiver (also referred herein to as a slave optical transceiver) an optical signal from a second optical transceiver (also referred herein to as a master optical transceiver).

At <NUM>, the slave optical transceiver detects, at an optical detector, a portion of the optical signal to produce a detected signal. The optical Rx signals are tapped by the optical tap and a portion of the optical Rx signals are detected in the optical detector. The optical detector can send the optical signals to a decoder of the slave optical transceiver.

At <NUM>, a decoder of the first optical transceiver decodes the detected signal to extract an encoded signal from the optical signal. The decoder extracts the embedded control information and the controller analyzes the control information to manage, control, or configure the master optical transceiver. Similar to the control information transmitted from the master optical transceiver to the slave optical transceiver, the control information received at the master optical transceiver from the slave optical transceiver can include an instruction to monitor, control, or configure the master optical transceiver (or multiple master optical transceivers), activate or deactivate an optical channel from the master optical transceiver, update a software program of the master optical transceiver, monitor optical signals received at the master optical transceiver 101and/or the like.

At <NUM>, the controller of the slave optical transceiver makes a control decision based on the encoded signal such that the slave optical transceiver modifies its operation based on the encoded signal.

Some embodiments described herein relate to a computer program product such as a computer storage product with a non-transitory computer-readable medium (also can be referred to as a non-transitory processor-readable medium) having instructions or computer code thereon for performing various computer-implemented operations. The computer-program product (or processor-readable medium) may be non-transitory in the sense that it does not include transitory propagating signals per se (e.g., a propagating electromagnetic wave carrying information on a transmission medium such as space or a cable) or transitory in the sense that it includes such signals or other transmission media. The media and computer code (also can be referred to as code) may be those designed and constructed for the specific purpose or purposes. Examples of non-transitory computer-readable media include, but are not limited to: magnetic storage media such as hard disks, floppy disks, and magnetic tape; optical storage media such as Compact Disc/Digital Video Discs (CD/DVDs), Compact Disc-Read Only Memories (CD-ROMs), and holographic devices; magneto-optical storage media such as optical disks; carrier wave signal processing modules; and hardware devices that are specially configured to store and execute program code, such as Application-Specific Integrated Circuits (ASICs), Programmable Logic Devices (PLDs), Read-Only Memory (ROM) and Random-Access Memory (RAM) devices. Other embodiments described herein relate to a computer program product, which can include, for example, the instructions and/or computer code discussed herein.

Examples of computer code include, but are not limited to, micro-code or microinstructions, machine instructions, such as produced by a compiler, code used to produce a web service, and files containing higher-level instructions that are executed by a computer using an interpreter. For example, embodiments may be implemented using imperative programming languages (e.g., C, Fortran, etc.), functional programming languages (Haskell, Erlang, etc.), logical programming languages (e.g., Prolog), object-oriented programming languages (e.g., Java, C++, etc.) or other suitable programming languages and/or development tools. Additional examples of computer code include, but are not limited to, control signals, encrypted code, and compressed code.

Therefore, from one perspective, there has been described an apparatus that includes a first optical transceiver. The first optical transceiver includes a set of optical transmitters, an optical multiplexer operatively coupled to the set of optical transmitters, and a variable optical attenuator operatively coupled to the optical multiplexer. The variable optical attenuator is configured to receive a control signal from a controller of the first optical transceiver and modulate a signal representing control information with an output from the optical multiplexer. The control information is associated with the control signal and for a second optical transceiver operatively coupled to the first optical transceiver.

Claim 1:
An apparatus, comprising:
a first optical transceiver (<NUM>) having:
a plurality of optical transmitters (<NUM>(<NUM>)...<NUM>(n)),
an optical multiplexer (<NUM>) operatively coupled to the plurality of optical transmitters, and
a variable optical attenuator (<NUM>) operatively coupled to the optical multiplexer,
the variable optical attenuator configured to receive a control signal from a controller (<NUM>) of the first optical transceiver,
the variable optical attenuator configured to modulate a first signal representing first control information with an output from the optical multiplexer to produce a first plurality of modulated optical signals, the first control information associated with the control signal,
the variable optical attenuator configured to send the first plurality of modulated optical signals to a second optical transceiver (<NUM>) operatively coupled to the first optical transceiver causing the second optical transceiver to manage or configure the second optical transceiver based on the first control information in response to receiving the first plurality of modulated optical signals,
the first optical transceiver is configured to receive a plurality of encoded optical signals from the second optical transceiver,
the first optical transceiver is configured to decode at least one encoded optical signal from the plurality of encoded optical signals to produce a second signal representing second control information associated with an operational status of the second optical transceiver, wherein
the second optical transceiver is included within a plurality of optical transceivers operatively coupled to the first optical transceiver,
the first optical transceiver is configured to send the first signal to each optical transceiver from the plurality of optical transceivers,
the first control information has a plurality of control information portions, each control information portion from the plurality of control information portions is associated with an optical transceiver from the plurality of optical transceivers and not associated with at least one optical transceiver from the plurality of optical transceivers.