Abstract:
A bi-directional light signal separation device that separates light signals into the component incoming and outgoing light signals has a a female connector that is connected to a near end of a first fiber optic cable conveying the bi-directional light signal. A light signal separation device connected to the female connector to separate the bi-directional light signal into the individual incoming and outgoing light signals. A plurality of second type connectors connected to convey the individual incoming or outgoing light signals. The light signal separation device has a plurality of light filters and reflectors such that a light signal incoming to the second type connector is transmitted through the filter and conveyed to the female connector and such that the light signal incoming from the first connector and reflected by the light filter is reflected and conveyed to be outgoing on the second connector.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to transmission and reception of electromagnetic signals in a medium. More particularly this invention relates to the multiplexing and demultiplexing of multiple signals from a cable. Even more particularly this invention relates to the separation simultaneously bi-directional light signals into its component incoming and outgoing signals. 
   2. Description of Related Art 
   Wavelength division multiplexing (WDM) is rapidly becoming the means for expanding the bandwidth or amount of information (data, telephony, or video) transported on fiber optic cables. Originally, the data modulated a single frequency or wavelength of light for transmission. The bandwidth being increased by employing time domain multiplexing (TDM) of the data signals. As the capacity of the installed base of the fiber optic cables became saturated with transmission of data, a method for increasing the capacity of the fiber optic cable became desirable. 
   The method developed to increase bandwidth use of fiber optic cable was wavelength division multiplexing. Light signals of different wavelengths are applied to a single fiber optic cable. The easiest, most cost effective method for wavelength division multiplexing is termed coarse wavelength division multiplexing (CWDM). Coarse wavelength division multiplexing employs light signal wavelengths that are widely separated to minimize light signal interaction or cross talk and allow the use of light signal separation techniques that are relatively simple. The light signal wavelengths are chosen such that the materials utilized have minimum dispersion and attenuation. The current preferred light signal wavelengths are 850 nm, 1310 nm, and 1550 nm. 
   Implementation of the wavelength domain multiplexing requires a multiplexer to combine the light signal wavelength for transmission of the combined light signals and a demultiplexer to separate the received light signals into the individual component light signals. Further, it is desirable to simultaneously transmit and receive signals from both ends of a fiber optic cable. This requires a combination of a multiplexer and demultiplexer to be present at both ends of the fiber optic cable. In fiber optic communication systems using two light signal wavelength such as 1310 nm and 1550 nm, the multiplexer/demultiplexer that separates the two bi-directional light signals is referred to as diplexers. Such companies as Koncent, Inc., Oplink Communications, Inc., and Harmonic, Inc. market diplexers or coarse wavelength division multiplexers that combine monochromatic light signals in the 1310 nm and 1550 nm wavelength range to form a bi-directional polychromatic light of the combined wavelengths and separate the bi-directional polychromatic light into the separate 1310 nm and 1550 nm wavelength light signals. 
   U.S. Pat. No. 5,673,342 (Nelson, et al.) teaches an optical fiber communication system having an optical fiber filter that can be manufactured at low cost and that can be conveniently incorporated into the system, substantially like a conventional fiber jumper. The filter comprises a length L of axially uniform optical fiber selected to have substantially no loss (e.g., &lt;1 dB) at a wavelength λ 1 , and to have relatively high loss (e.g., &gt;20 dB) at a wavelength λ 2 . The length L will typically be less than 100 m. In one embodiment the optical fiber is a single mode optical fiber at λ 1  (e.g., 1.3 μm) that does not have a guided mode at λ 2  (e.g., 1.55 μm). In another embodiment the fiber contains a dopant that does not substantially absorb radiation of wavelength λ 1 , but substantially absorbs at λ 2 . In the second embodiment, λ 1  can be greater than λ 2 . 
   U.S. Pat. No. 6,289,148 (Lin, et al.) teaches a free-space micro-mirror wavelength add/drop multiplexer with full connectivity for two-fiber ring networks. The free-space nature of the switch mirrors allows use of the front and back sides of the mirrors for reflecting signals. According to one embodiment of the present invention a wavelength add/drop multiplexer is provided in which micro machined switch mirrors are arranged in a polygonal (e.g., hexagonal) geometry, which allows full connectivity. According to one embodiment a wavelength add/drop multiplexer is provided for deployment in a unidirectional two-fiber optical network including service and protection fiber routes. According to this embodiment the wavelength add/drop multiplexer includes a first input port for receiving a wavelength division multiplexed signal from the service fiber route and a second input port for receiving a wavelength division multiplexed signal from the protection fiber route. The wavelength add/drop multiplexer also includes a first output port for transmitting a wavelength division multiplexed signal to the service fiber route, a second output port for transmitting a wavelength division multiplexed signal to the protection fiber route, a third input port for receiving local signals from a local access port and a third output port for dropping signals to a local access port. The wavelength add/drop multiplexer further includes a reconfigurable switching matrix comprising a plurality of free-space micro mirrors, for performing routing of signals from the various input ports to the various output ports. According to an alternative embodiment a wavelength add/drop multiplexer is provided for deployment in a bi-directional two-fiber optical network including two service/protection routes. 
   U.S. Pat. No. 6,289,155 (Wade) discusses wavelength division multiplexing/demultiplexing devices using dual high index of refraction crystalline lenses. The wavelength division multiplexing device comprises a crystalline collimating lens for collimating a plurality of monochromatic optical beams, a diffraction grating for combining the plurality of collimated, monochromatic optical beams into a multiplexed, polychromatic optical beam, and a crystalline focusing lens for focusing the multiplexed, polychromatic optical beam. 
   U.S. Pat. No. 6,339,663 (Leng, et al.) provides a bi-directional wavelength division multiplexed optical communication system having bi-directional optical service channels. The bi-directional WDM optical communication system includes a bi-directional optical waveguide configured to carry a bi-directional optical communication signal comprising counter propagating WDM optical signals. Each WDM optical signal includes plural optical channels and an optical service channel. A bi-directional optical add-drop multiplexer optically communicates with the waveguide. A first optical service channel selector optically communicates with the first bi-directional optical add-drop multiplexer input/output port. The first optical service channel selector is configured to separate the first optical service channel from the first WDM optical communication signal such that the first WDM signal enters the first input/output port of the bi-directional optical add-drop multiplexer and the first optical service channel is routed to a service channel module. Similarly, a second optical service channel selector optically communicates with the second input/output port of the bi-directional optical add-drop multiplexer and routes the second optical service channel to a service channel module. 
   U.S. Pat. No. 4,776,660 (Mahlein, et al.) teaches a light branching element or diplexer comprising a first bi-directional light connection and a second and third unidirectional light connection. The unit is formed by a block having a straight surface groove with an embedded glass fiber which fiber is interrupted by a partially transmissive mirror lying on a slanting plane relative to the axis of the fiber. The light sensitive location of a light receiving semiconductor element is secured to the block adjacent to the mirror and the plane of the mirror is selected so that its normal extends out of the block at an angle of incidence smaller than 45° to the axis of the fiber to reduce reflections from the semiconductor member back to the mirror and into the fiber. 
   U.S. Pat. No. 5,144,637 and U.S. Pat. No. 5,031,188 (Koch, et al.) present a diplex lightwave transceiver that achieves full duplex light wave communications. The diplex transceiver is realized in a semiconductor photonic integrated circuit having an inline interconnecting waveguide integral with the transmitting and receiving portions of the transceiver. Semiconductor lasers and detectors operating at different wavelengths permit diplex or wavelength-division-multiplexed operation. In the transceiver, light wave signals from the laser propagate through the detector without interfering with the detector operation or the light wave signals being detected. 
   U.S. Pat. No. 5,712,864 (Goldstein, et al.) discusses a semiconductor photonic diplex transceiver. The photonic diplex transceiver includes a laser to generate a first optical signal having a certain wavelength and a photodetector to detect a second optical signal having another wavelength. The diplex transceiver also includes an absorber of the first signal disposed between the laser and the detector, which form integral parts of an optical waveguide. The laser generates the first signal in the form of a continuous wave and is disposed between the absorber and a selective modulator of the first signal. This reduces the problems of optical and electrical crosstalk between the transmit and receive functions. 
   “Bi-directional Single Fiber Links for Base Station Remote Antenna Feeding,” Steiner et al., European Conference on Networks &amp; Optical Communications NOC 2000, Jun. 6–9, 2000, Stuttgart, Germany, discusses a bi-direction module employing a WDM beam splitter. 
   “1.3/1.55 Microns Duplex-Diplex Optical Transmission: The Brazilian Technology,” Celaschi, et al., Telecommunications Symposium, 1990. ITS &#39;90 Symposium Record, SBT/IEEE International, pp. 454–457, September 1990, Rio de Janeiro, Brazil, presents results from the first experimental Brazilian route in which two separate optical channels have been combined in both duplex and diplex transmission. The experiments were demonstrated over 18 km of standard single-mode fiber using 1.29 and 1.52 micron edge-emitting laser diodes at 34 Mbit/s. The optical emitters and detectors were linked to the single mode fiber through specially designed wavelength division multiplexing couplers. The results indicate that either duplex or diplex transmission can be implemented in any installed standard single mode route up to 40 km. 
   “A 1.3/1.55 μm Wavelength-Division Multiplexing Optical Module Using a Planar Lightwave Circuit for Full Duplex Operation,” Hashimoto, et al.”, Journal of Lightwave Technology, IEEE, November 2000, Volume: 18 Issue: 11, pp. 1541–1547, discusses development of a hybrid integrated optical module for 1.3/1.55 μm wavelength-division multiplexing (WDM) with full-duplex operation. The optical circuit was designed to suppress the optical and electrical crosstalk using a wavelength division multiplexing filter, and an optical crosstalk of −43 dB and an electrical crosstalk of −105 dB were achieved with a separation between the transmitter laser diode and the receiver photodiode of more than 9 mm. 
   “Planar Lightwave Circuit Platform with Coplanar Waveguide For Opto-Electronic Hybrid Integration,” Mino, et al., Journal of Lightwave Technology, IEEE, December 1995, Volume: 13 Issue: 12, pp. 2320–2326 describes a planar lightwave circuit (PLC) platform constructed on a silica-on-terraced-silicon (STS) substrate for opto-electronic hybrid integration. This platform consists of an embedded silica PLC region, a terraced silicon region for optical device assembly, and a high-speed electrical circuit region. In the electrical circuit region, the coplanar waveguides (CPW) are prepared on a thick-silica/silicon substrate. This structure reduces the propagation loss of the CPW drastically to 2.7 dB/cm at 10 GHz, because the loss tangent (tan Δ) of the dielectric constants of silica is much smaller than that of silicon. 
   SUMMARY OF THE INVENTION 
   An object of this invention is to provide a device for separation of bi-directional light signal into the component incoming and outgoing light signals. 
   To accomplish this object, a fiber optical signal separation apparatus has a substrate onto which a female type connector is attached. The female type connector is connected to a near end of a first fiber optic cable conveying the bi-directional light signal. A light signal separation device is affixed to the substrate and connected to the female type connector to separate the bi-directional light signal into the individual incoming and outgoing light signals. A plurality of second type connectors are attached to the substrate and connected convey the individual incoming or outgoing light signals. 
   The fiber optic signal separation apparatus has a first graded index lens placed between the female type connector and the light signal separation device to concentrate the bi-directional light signal prior to conveyance between the female connector and the light signal separation device. A first ferrule containing a fiber optic core is placed between the female type connector and the first graded index lens to transfer the bi-directional light signal between the female type connector and the first graded index lens. 
   The fiber optic signal separation apparatus has a plurality of second graded index lenses. Each second graded index lens is placed between one of the plurality of second type connectors and the light signal separation device to concentrate one of the individual incoming or outgoing light signals. The fiber optic signal separation apparatus further has a plurality of second ferrules. Each of second ferrules contains a fiber optic core and is placed between one of the plurality of second graded index lenses and one of the plurality of second type connectors to transfer one of the individual incoming or outgoing light signals. 
   The light signal separation device is comprised of a plurality of light filters attached to the substrate. Each light filter is aligned such that light signals incoming from the female type connector are reflected by the light filter and aligned with one of the second type connectors such that a light signal incoming to the second type connector is transmitted through the filter and conveyed to the female type connector. The light signal separation device also has a plurality light reflectors attached to the substrate. Each light reflector is aligned with the light filter and with one of the second type connectors such that the light signal incoming from the female type connector and reflected by the light filter is reflected and conveyed to be outgoing on the second type connector. 
   Alternately, the light signal separation device has a plurality of light couplers attached to the substrate. Each light coupler has a first port connected to the female type connector to convey the bi-directional light signal. A second port is connected to one of the second type connectors to receive the incoming light signal and convey the incoming light signal to the female type connector for transmission to the first fiber optic cable. A third port is connected to one of the second connectors to transmit an incoming signal of the bi-directional signal from the female type connector to one of the second fiber optic cables. A separation coupler directs the incoming light signal from one of the second connectors to the female type connector and to direct the incoming light from the first female connector to another of the second connectors. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram illustrating a first embodiment a diplexer of this invention. 
       FIG. 2  is a schematic diagram illustrating a second embodiment a diplexer of this invention. 
       FIG. 3  is a top plan view of a first mode of the first embodiment of the diplexer of this invention. 
       FIG. 4  is a top plan view of a second mode of the first embodiment of the diplexer of this invention. 
       FIG. 5  is a top plan view of the second embodiment of the diplexer of this invention. 
       FIGS. 6   a – 6   d  are respectively the front, top, left side, and right side plan views of the packaged diplexer of this invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Wide bandwidth networks such as those used to communicate data, telephony, and video within a metropolitan area have routers that provide steering of the wideband data, telephony, and video signals between nodes of the network. The router systems are composed of switch cards that receive, route, and retransmit the wideband data, telephony, and video signals between the nodes of the network. Generally, the switch cards currently have only an electronic interface for the transmitters and receivers of the links to carry the wideband data, telephony, and video signals. To provide for fiber optic cabling as the physical link from the nodes of the network to the switch cards, fiber optic transmitters and receivers are placed at the interface of the switch cards and the fiber optic cabling. 
   Small form factor pluggable transceiver modules now manufactured by such companies as Stratos Lightwave, Inc. and Finisar Corporation provide optical transmitters and receivers that couple the wideband data, telephony, and video signals modulated on a light signal to the fiber optic cables. These small form factor pluggable transceiver modules are packaged such that they have electrical connectors that mate with a single port of the switch and fiber optic connectors that mate with the fiber optic cables. The spacing of the small form factor pluggable transceiver modules is such that all ports present on the switch have a small form factor pluggable transceiver module connected to each port. The switches transmit the wideband data, telephony, and video signals to be routed to a port on one cable while receiving the wideband data, telephony, and video signals on a second port. This forces each switch of a router to have two cables (one transmit cable and one receive cable) connected to each port of the switch. In networks where there is increasing demand for the wideband data, telephony, and video signals, increasing the number of ports of the switch and the number of nodes on the network requires doubling the number fiber optic cables installed in the network. 
   As described above, wavelength domain multiplexing allows light signals of multiple wavelengths (λ) to be transferred on a single fiber optic cable. The small form factor pluggable transceiver modules as described do not have a facility for providing the wavelength domain multiplexing to reduce the required number of fiber optic cables as the network increase in the number of nodes. A diplexer, as described above, provides the combination and separation of transmitted and received light signals to allow the simultaneous bi-directional transmission light signals on a single fiber optic cable. 
   Refer now to  FIG. 1  for a description of the diplexer of this invention. The diplexer  10  is connected to the small form factor pluggable transceiver module  15  to couple the light signals λ 1    60  and λ 2    65  from and to the transceiver module  15 . The light signals λ 1    60  and λ 2    65  are modulated with the wideband data, telephony, and video signals from the switch or node originating the wideband data, telephony, and video signals. The small form factor pluggable transceiver module  15  has a receiver  25  that receives the light signal λ 2    65  from the fiber optic cable  85  and a transmitter  30  that transmits the light signal λ 1    60  to the fiber optic cable  85 . The diplexer  10  providing the combination and separation of the signals to allow the simultaneous bi-directional transmission of the light signals λ 1    60  and λ 2    65 . 
   The connectors  50  and  55  are attached to a substrate  45 . The connector  50  is aligned to be inserted to mate with the connector  35  of the transmitter  30  and the connector  55  is aligned to be inserted to mate with the connector  40  of the receiver  25 . The optical filter  70  is mounted on the substrate. The optical filter  70  is constructed to be transmissive to the wavelength of the light signal λ 1    60  and reflective to the wavelength to the light signal λ 2    65 . The optical filter is then aligned with the connector  50  and the female connector  80  to allow the light signal λ 1    60  to pass through the optical filter  70  to the female connector  80  and into the fiber optic cable  85  for transmission to the receiver at the distal end of the fiber optic cable  85 . 
   A mirror  75  that is reflective to the wavelength of the light signal λ 2    65  is attached to the substrate and aligned with the connector  55  to transmit the light signal λ 2    65  through the connector  55  to the receiver  25 . The filter  70  and the mirror  75  are oriented and aligned with respect to each other to allow the light signal λ 2    65  transferred from the fiber optic cable  85  through the female connector  80  to reflect from filter  70  to the mirror  75  and from the mirror  75  to the connector  55 . 
   The diplexer  10  of this invention is packaged and contained within the substrate  45  and has no “pig tail” fiber optic cables as the diplexers of the prior art. The diplexer  10  of this invention allows the fiber optic cable  85  installed to connect another node or switch to the node or switch connected to the small form factor pluggable transceiver module  15  to be easily installed. No special connectors are required to be affixed to the diplexer  10  as with the diplexers of the prior art. 
   The optical filter  70  of the diplexer  10  is designed such that the wavelength of the light signals λ 1    60  and λ 2    65  are different depending on the wavelength of the light signals being transmitted or being received. In coarse wavelength division multiplexing as currently practiced the common wavelengths are 1310 nm and 1550 nm. The combinations of the wavelengths transmitted and reflected by the optical filter are shown in Table 1. 
   
     
       
             
             
             
           
         
             
                 
               TABLE 1 
             
             
                 
                 
             
             
                 
               λ 1  60 
               λ 2  65 
             
             
                 
                 
             
           
           
             
                 
               1310 nm 
               1550 nm 
             
             
                 
               1550 nm 
               1310 nm 
             
             
                 
                 
             
           
        
       
     
   
   Referring to  FIG. 2 , the small form factor pluggable transceiver module  15  may be configured to transmit and the receive the light signals having the same wavelength. In the case of the current wavelengths this means that the transmitter  30  and the receiver  25  both operate at either 1310 nm or 1550 nm. In the second embodiment of the diplexer, as shown in  FIG. 2 , the connectors  50  and  55  are respectively connected to the connectors  35  and  40 . The coupler  100  is a fused optical coupler that is used to split optical signals between two fibers, or to combine optical signals from two fibers into one fiber. The optical coupler  100  is constructed by fusing and tapering two fibers together. 
   The transmitted light signal λ 1T    110  is conveyed from the transmitter  30  through the connectors  35  and  50  to the coupler  100 . The coupler  100  transfers the transmitted light signal λ 1T    110  to the female connector  80  to the fiber optic cable  85 . The received light signal λ 1R    105  is transferred through the female connector  80  to the coupler  100 . The coupler  100  directs the light signal λ 1R    105  through the connectors  55  and  40  to the receiver  25 . 
   Refer now to  FIG. 3  for a discussion of a physical implementation of a first variation of the first embodiment of the diplexer of this invention. The female connector  280  is secured to the substrate  200  and is structured to receive the connector terminating the near end of the fiber optic cable containing the bi-directional light signals λ 1    260  and λ 2    265 . Linked to the female connector  280  is a ferrule  205 . The ferrule  205  is a component (usually a rigid tube) used to align and protect the stripped end of a fiber optic core  207 . A ferrule is used together with the female connector  280  that connects to the connector terminating the end of the fiber cable. The ferrule  205  keeps the fiber optic cores accurately aligned within the connector. Ferrules can be made of glass, plastic, metal, or ceramic material. The ferrule  205  is attached to the substrate  200 . 
   A graded index lens  210  is attached to the substrate and aligned to the ferrule  205  to allow transfer of the light signals λ 1    260  and λ 2    265  from and to the female connector  280 . The graded index lens  210  concentrates or focuses the light signals λ 1    260  and λ 2    265  from the optical filter  270  to the ferrule  205  and from the ferrule  205  to the optical filter  270 . 
   The optical filter  270  is mounted to the substrate  200  and is constructed to be transmissive to the wavelength of the light signal λ 1    260  and reflective to the wavelength to the light signal λ 2    265 . The light signal λ 1    260  is transferred through the optical filter  270  from the graded index lens  215 . The graded index lens  215  is mounted to the substrate and aligned to transfer the light signal λ 1    260  to the optical filter  270 . The ferrule  220  containing the fiber optical core  222  is attached to the substrate  200  and functions as described for the ferrule  205 . The ferrule  220  is aligned to a second ferrule  225  containing the fiber optical core  227 . The ferrule  225  is a component part of the connector  250  and transfers the light signal λ 1    260  from the transmitter through the filter  270  and ultimately to the fiber optic cable. 
   The light signal λ 2    265  is reflected from the filter  270  to the mirror  275 . The mirror  275  is attached to the substrate  200  and is aligned and oriented with the filter  270  such that the light signal λ 2    265  is transferred from the female connector  280  through the ferrule  205  and the graded index lens  210  to be reflected from the filter  270  to the mirror  275 . The light signal λ 2    265  is then reflected from the mirror  275  to the graded index lens  230 . 
   The graded index lens  230  is attached to the substrate  200  and placed adjacent to the ferrule  235 , which contains the fiber optic core  237 . The graded index lens  230  concentrates or focuses the light signal λ 2    265  to the fiber optic core  237  of the ferrule  235 . The ferrule  235  is secured to the substrate  200  and adjoins the ferrule  240 , which contains the fiber optic core  242 . The fiber optic cores  237  and  242  are aligned to allow transference of the light signal λ 2    265 . The ferrule  240  is a component part of the connector  255  for linking with the connector of the small form factor pluggable transceiver module. The connector  255  is attached to the substrate  200 . 
   A second variation of the first embodiment of the diplexer of this invention, as shown in  FIG. 4 , excludes the ferrules  220  and  235  with their enclosed fiber optic cores  222  and  237 . The graded index lens  215  is now attached to the substrate  200  adjacent to the ferrule  225  and aligned to receive the light signal λ 1    260  from the fiber optic core  227 . This allows the light signal λ 1    260  to be transferred from the fiber optic cable through the connector  250  to the filter  270 . The light signal λ 1    260 , as described above is transmitted through the filter  270 , the graded index lens  210 , the ferrule  205 , and female connector  280 . 
   The graded index lens  230  is attached to the substrate  200  and situated adjacent to the ferrule  240  and aligned such that the light signal λ 2    265  is concentrated on the fiber optic core  242 . Thus the light signal λ 2    265  is transferred from the female connector  280  to the filter  270  as described above. The light signal λ 2    265  is then reflected to the mirror  275  to the graded index lens  230  for concentration to the fiber optic core  242 . 
   The ferrules  205 ,  225 , and  240  in the first and second variations of the first embodiment of the diplexer of this invention are ceramic ferrules. The ferrules  220  and  235  are glass ferrules. The ceramic ferrules employed for the ferrules  205 ,  225 , and  240  are chosen for their strength and durability. The ferrules  205 ,  225 , and  240  are to respectively components of the female connector  280  and connectors  250  and  255  and will be mating with the connectors of the transceiver module  15  and the female connector  80  of the fiber optic cable  85  of  FIG. 1 . The ferrules  220  and  235  to retain the graded index lens  215  and  230  and do not require the strength of the ceramic ferrule and thus may use the more economical glass ferrule. It is in keeping with the intent of this invention that the ferrules be constructed of any suitable material. 
   The second embodiment of the diplexer of this invention, as shown in  FIG. 5 , has a substrate  300  onto which a female connector  380  is attached. The female connector  380  receives the terminating end of the fiber optic cable having the bi-directional light signals λ 1    110  and λ 2    105  of  FIG. 2 . Affixed to the substrate  300  and the female connector  380  is the ferrule  305 . The ferrule  305  has the fiber optic core  307  that extends from the ferrule  305  to the coupler  310 , which is a fused optical coupler that functions as the coupler  100  of  FIG. 2 . 
   The connector  350  has as a component the ferrule  325  containing the fiber optic core  327 . The connector  350  is connected to the transmitter  30  of  FIG. 2  and conveys the light signal light signal λ 1T    110  through the fiber optic core  327  to the coupler  310 . Similarly, the light signal λ 1R    105  is conveyed from the fiber optic cable connected to the female connector  380  to through coupler to the fiber optic core  342 . The fiber optic core  342  is contained in the ferrule  340  and extended to connect to the coupler  310 . The ferrule  340  is a component of the connector  355  that is connected to the receiver  25  of  FIG. 2 . The light signal λ 1R    105  is propagated through the fiber core  342  and is received by the receiver  25  of  FIG. 2 . 
   The ferrules  305 ,  325 , and  340  of the second embodiment of the diplexer of this invention are ceramic ferrules. 
   The first embodiment of the diplexer of this invention illustrates the splitting and combining of two bi-directional light signals of different wavelengths. It is in keeping with the intention of this invention that the two bi-directional light signals of the first embodiment of this invention may have the same wavelength and perform similarly to that shown in  FIG. 2 . Similarly the second embodiment of the diplexer of this invention illustrates the combining and splitting of two bi-directional light signal of the same wavelength. It too is in keeping with the intent of this invention that the two bi-directional signals of the second embodiment of this invention may have different wave lengths and perform similarly to that shown in  FIG. 1 . 
   Refer now to  FIGS. 6   a – 6   d  for a description of the packaged diplexer  10  of this invention. The substrate  45  onto which the components of the diplexer  10  are mounted has a covering  12  secured to prevent dust and contamination from impacting on the components of the diplexer  12 . The connectors  50  and  55  are structured for plugging into the small form factor pluggable transceiver module  15  of  FIGS. 1 and 2 . The female connector  80  is designed to accept the terminating connector of the fiber optic cable  85  of  FIGS. 1 and 2 . 
   The connectors  50  and  55  and female connector  80  are constructed of any suitable connector form factor, which is determined by the terminating end of the fiber optic cable and the connectors of the small form factor pluggable transceiver module. Generally the connectors are the types generally employed within the optical communications industry. The preferable connectors are the types LC, MT-RJ, MU, and the SC known in the art. 
   While this invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.