Abstract:
A detachable optical transceiver includes an optical part configured to convert an electric signal into an optical signal and transmit the optical signal, or to convert an optical signal into an electric signal and output the electric signal; and an electronic circuit part configured to amplify an electric signal input from a host board and output the amplified electric signal to the optical part, and to amplify an electric signal output from the optical part and output the amplified electric signal to the host board, wherein the optical part and the electronic circuit part are formed to have housings and the optical part and the electronic circuit part are connected and disconnected via connectors formed on the respective housings.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority from Korean Patent Application No. 10-2013-0109341, filed on Sep. 11, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The following description relates to an optical transceiver, and more particularly, to a detachable optical transceiver with a detachable part for performing optical processing. 
         [0004]    2. Description of the Related Art 
         [0005]    With the advent of smart devices, such as smart phones, smart TVs, and the like, an excess amount of traffic results in wired and wireless networks. Many researches on the application of a wavelength division multiplexing-based technology to a cable subscriber network or a wired-wireless integrated network to effectively cope with such traffic issues has been conducted. 
         [0006]    Wavelength division multiplexing (WDM) is a technology which multiplexes a number of optical wavelengths and transmits and receives the multiplexed signals over a single strand of fiber. The WDM technology can reduce the cost for paths in proportion to the number of optical wavelengths supported by one strand of fiber, and as separating channels by light wavelengths, WDM can have more advantages in terms of security, quality of service (QoS), and protocol transparency, in comparison with other technologies. 
         [0007]    However, to exploit the WDM technology, a different wavelength needs to be assigned to each optical network unit to enable the communication, and thus as many optical transceivers with their own unique wavelengths are required as the number of subscribers to a cable subscriber network branched by a remote node or as the number of separated base stations used in a wired-wireless integrated network. 
         [0008]    Requiring different types of unique wavelength optical transceivers may mean that multiple particular optical transceivers with different wavelengths should be produced, installed, maintained, and prepared in anticipation of any defects. This may be a great burden to network service providers. 
         [0009]    Therefore, to alleviate such load for the service providers, research and development on colorless optical transceiver have been actively carried out. An optical transceiver with a reflective light source, such as a reflective semiconductor optical amplifier or a Fabry-Perot laser diode, and an optical transceiver with wavelength-variable light source are used as representative colorless optical transceivers. 
         [0010]    The optical transceiver with a reflective light source has a drawback that the quality of signal transmission is dependent on the type and optical power of light externally injected. On the other hand, the wavelength-variable optical transceiver with a wavelength-variable light source uses heat, electricity, physical force as variables, thereby producing a light output with a wavelength varying depending on a control value. A control value needs to be mapped for each light output wavelength in advance. Further, technology to monitor and control an output wavelength needs to be applied and the wavelength-variable optical transceiver is expensive to use in a subscriber network. 
         [0011]    As another method of implementing an optical transceiver with various types of unique wavelengths, a wavelength selector that decides an output wavelength of laser is configured to be detachable by separating it from an external resonant laser that comprises a gain medium and the wavelength selector. However, in this method, the resonance characteristics of the external resonant laser may be altered according to the conditions in which the wavelength selector is detached and attached, and there are several prerequisites to be addressed in terms of reliability of the light source, which impedes the commercialization. 
         [0012]    As for the above reasons, an optical transceiver using a light source, such as a distributed feedback (DFB) laser diode or VCSEL, which has a fixed wavelength, is currently generally used, and if the output wavelength needs to be changed, an optical transceiver may be replaced with an appropriate one. The replacement of optical transceiver may be needed in following cases: where temperature control for an optical module is required due to a change in precision conditions of an output wavelength of an optical transceiver. Where there is a need for change in an output wavelength of the optical transceiver. Where an optical detector of an optical receiver within the optical transceiver needs to be replaced or an optical transmitter needs to be replaced with a new optical transmitter with a different optical power, due to the change in a transmission distance. Where a different data transfer speed is required so that an optical receiver equipped with a pre-amplifier having a frequency response characteristic conforming to the data transfer speed is needed or an optical transmitter with a frequency response characteristic satisfying the requirement is needed. Where the optical transceiver has a degraded part, resulting in a failure to meet the system performance requirements, and thus the part of the optical transceiver needs to be replaced. 
       SUMMARY 
       [0013]    The following description relates to a detachable optical transceiver including detachable optical transmitting and receiving parts and a detachable electronic circuit part, and being capable of being configured to selectively include an optical part that meets performance requirements of a network or system. 
         [0014]    In one general aspect, there is provided a detachable optical transceiver including: an optical part configured to convert an electric signal into an optical signal and transmit the optical signal, or to convert an optical signal into an electric signal and output the electric signal; and an electronic circuit part configured to amplify an electric signal input from a host board and output the amplified electric signal to the optical part, and to amplify an electric signal output from the optical part and output the amplified electric signal to the host board, wherein the optical part and the electronic circuit part are formed to have housings and the optical part and the electronic circuit part are connected and disconnected via connectors formed on the respective housings. 
         [0015]    Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a diagram illustrating a general optical transceiver. 
           [0017]      FIGS. 2A and 2B  are diagrams illustrating an exterior of the general optical transceiver of  FIG. 1 . 
           [0018]      FIG. 3  is a diagram illustrating an exterior of a detachable optical transceiver according to an exemplary embodiment. 
           [0019]      FIG. 4  is a diagram illustrating a configuration of the detachable optical transceiver of  FIG. 3 . 
       
    
    
       [0020]    Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience. 
       DETAILED DESCRIPTION 
       [0021]    The following description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. Accordingly, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be suggested to those of ordinary skill in the art. Also, descriptions of well-known functions and constructions may be omitted for increased clarity and conciseness. 
         [0022]    An optical transceiver referred to in the following description may be in the form defined by MSA standards, such as 10 Gigabit Small Form Factor Pluggable (XFP), Small-Form-Factor Pluggable (SFP), Small-Form-Factor (SFF), Gigabit Interface Converter (GBIC), X2, XENPAK, and the like, or be 
         [0023]      FIG. 1  is a diagram illustrating a general optical transceiver. 
         [0024]    Referring to  FIG. 1 , the optical transceiver may largely consist of an optical transmitting part, an optical receiving part, and a control part. 
         [0025]    The optical transmitting part may include a laser diode (LD) driver  10  and an optical transmission assembly (e.g., Transmit Optical Sub-Assembly (TOSA)  11 . The optical receiving part may include a limiting amplifier  20  and an optical receiver assembly (e.g., Receive Optical Sub-Assembly (ROSA))  21  equipped with a pre-amplifier. The control part may include a controller  30  and a thermo electric cooler controller (TEC controller)  31 , and further include a power supply  40 , a ground  41 , and an avalanche photo diode (APD) direct-current (DC) voltage controller  60  for an avalanche photo diode. 
         [0026]    When classified in a different way, the optical transmission assembly  11  and the optical receiver assembly  21  may be included in an optical part to perform optical processing, and the other elements may be classified into an electronic circuit part to control the optical part. 
         [0027]    Conventionally, the optical part and the electronic circuit part are integrated into one piece. That is, an electric board integrating the electronic circuit part  71  and the optical part  72 , as shown in  FIG. 2B , may be mounted within a single housing  70  shown in  FIG. 2A . 
         [0028]    However, to improve the conventional optical transceiver as described above, the electronic circuit part or the housing may be commonly managed, and the optical part that determines an output wavelength may be separately configured. In other words, the optical part with optical properties which are required when building a system may be used as an optical transceiver which is detachable from the electronic circuit part. 
         [0029]      FIG. 3  is a diagram illustrating an exterior of a detachable optical transceiver according to an exemplary embodiment. 
         [0030]    Referring to  FIG. 3 , the detachable optical transceiver includes an optical part  100  and the electronic circuit part  200 , which have individual housings  110  and  210 , respectively. A first connector  120  and a second connector  220  which are formed on the respective housings  110  and  120  allow for connecting and disconnecting between the optical part  100  and the electronic circuit part  200 . The connectors  120  and  220  have frequency response properties required in a system, and the number of pins is dependent on the number of signals to be transmitted and received. 
         [0031]    A first connector  120  may protrude from one side of the housing  110  of the optical part  100  so as to connect the optical part  100  and the housing  210  of the electronic circuit part  200 , or may be formed as an insertable connector with a recess in a shape reverse to the shape illustrated in  FIG. 3 . Although not illustrated, for example, an elastic hook, a stopper formed on the housing of the optical part  100  to allow the optical part  100  to be elastically coupled to electronic circuit part  200  by an elastic connection with the elastic hook, and a guiding groove to guide the elastic hook to the stopper and to prevent the elastic hook to be exposed to the outside. 
         [0032]    In one example, the first connector  120  may be formed as a flexible electronic circuit board which can be inserted in a direction toward the electronic circuit board  200 . 
         [0033]    The second connector  220  may connect the optical part  100  to one end of the housing  210  of the electronic circuit part  200  such that the optical part  100  is detachably coupled to the electronic circuit part  200 . Although not illustrated, the second connector  220  may include a socket within the housing  210  of the electronic circuit part  200  into which pins extending from the optical transmission assembly and optical receiver assembly of the optical part  100  are connected, and a receiving recess may be formed on one end of the housing  210  of the electronic circuit part  200  so as to enable pins of the optical transmission and receiver assemblies equipped within the optical part  100  to be stably connected to the socket. The receiving recess may be a multi-stepwise recess to prevent the optical transmission assembly and the optical receiver assembly from moving. 
         [0034]    In addition, the first connector  120  and the second connector  220  may be connected and disconnected only by means of a key provided to an authorized user, and a latch may be provided for this purpose. 
         [0035]    Further, the first connector  120  and second connector  220  may have housings in asymmetric shapes in order to prevent the left and right of the connectors  120  and  220  from being switched. 
         [0036]    The housing  110  of the optical part  100  may have a thermal resistance. For the thermal resistance, the housing may be formed of a material with good thermal resistance properties, or an individual means with thermal resistance capabilities may be added. Moreover, to improve the thermal contact, each of the first connector  120  and the second connector  220  may have a contacting portion formed of a metallic material with excellent thermal conductive properties. 
         [0037]    Further, the contacting portion of each of the connectors may be formed as a connecting portion with a flexible printed circuit board. 
         [0038]      FIG. 4  is a diagram illustrating a configuration of the detachable optical transceiver of  FIG. 3 . 
         [0039]    Referring to  FIG. 4 , an interior part  130  mounted on the optical housing  110  includes an optical transmission assembly  131  and an optical receiver assembly  132 . In another example, the optical transmission assembly and the optical receiver assembly may be integrated into one entity functioning as a bidirectional optical sub-assembly (BOSA). 
         [0040]    The optical transmission assembly  131  converts an electric signal output from the electronic circuit part  230  into an optical signal and outputs light containing the optical signal. The number of connection pins of the optical transmission assembly  131  and the optical receiver assembly  132  may be dependent on the number of electric signals to be transmitted to and received from the electronic circuit part  230 . 
         [0041]    The optical transmission assembly  131  and the optical receiver assembly  132  may each be made in the form of a pigtail or receptacle connector. 
         [0042]    The optical transmission assembly  131  may have a single channel optical transmission module embedded therein, or an optical transmission module array embedded therein. Also, the optical receiver assembly  132  may have a signal channel optical receiver module embedded therein, or an optical receiver module array embedded therein. In a case where the optical transmission module array or the optical receiver module array is embedded in the assembly, an MPO connector may be attached to the assembly. 
         [0043]    Additionally, the optical part  130  may previously store identification (ID) information containing driving control value information for optimal operations and output wavelength and optical power of the optical part  130 , using EEPROM or the like. Further, the optical part  130  may include a slow starter-related circuit portion to enable plug-and-play even when the optical transceiver is connected to a power source by being plugged into a host board  300 . 
         [0044]    The circuit board  230  mounted within the housing  210  of the electronic circuit includes a laser diode driver  231 , a limiting amplifier  232 , a controller  223 , a power supply  235 , and a ground  236 . The circuit board  230  may additionally include a thermo electric cooler controller (TEC controller)  234 , and an APD DC voltage controller  250  to drive an avalanche photo diode. The additional thermo electric cooler controller  234  or the APD DC voltage controller  250  may be included in an electronic circuit part  230 , or may be disposed on a separate printed circuit board (PCB), which is afterwards attached onto a top surface or a lower surface of the electronic circuit part  230 . The optical driver and the limiting amplifier may be in the form of an integrated circuit. The laser diode driver and the limiting amplifier may be capable of providing a multi-rate support. The limiting amplifier may have a function to vary a decision threshold. 
         [0045]    The controller  233  monitors whether the optical part  100  is connected to or disconnected from the electronic circuit part  200 . In addition, the controller  233  controls the optical transmission assembly  131  and the optical receiver assembly  132  when the optical part  100  is connected to the electronic circuit part  200 . Further, the controller  233  may report to the host board  300  as to whether the optical part  100  is connected to or disconnected from the electronic circuit part  200 . For example, the controller  233  may report to the host board using a signal, for example, MOD_DEF(0). 
         [0046]    The optical transceiver and the host board  300  may have Tx_Disable, Tx_Fault, LOS, power supply, and GND lines connected thereto, including Tx +/− and Rx +/− data signals, and may conform to particular MSA standard specifications in accordance with the purpose of the detachable optical transceiver. 
         [0047]    The laser diode driver  231  may be included in the optical part  130  for high speed digital signal transmission. 
         [0048]    According to the exemplary embodiments, the optical part is detachable, and thus a WDM optical transceiver can be easily manufactured and its component management is facilitated. Further, when a particular part of the optical transceiver is deteriorated, only the part needs to be replaced and the other parts of the optical transceiver can be continuously used, thereby achieving cost reduction. 
         [0049]    A number of examples have been described above. Nevertheless, it will be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.