JPH07176716A - Interconnection device - Google Patents

Abstract

PURPOSE: To achieve a device that is easily used for transferring much information efficiently between circuit part substrates such as printed wiring boards and can transfer the information in this manner. CONSTITUTION: Printed wiring boards 11A-E that are arranged nearly in parallel support a light source element 13A-E and a photo detector 14A-E. Each light source element is connected to all photo detectors of another printed wiring board by an optical fiber that is supported in an arc-shaped groove 16 of a light backplane member 12. Also, each light source element is connected also to a light source terminal, and each photo detector is connected to the terminal of the detector, thus forming a bias interconnection between specific light source element and photo detector. In another embodiment, the wide surface of the light backplane contacts the edge part of the printed wiring board.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to optical interconnections. More particularly, the present invention relates to optical backplanes having fiber optic interconnects.

[0002]

Two important trends in information management and communication technology in recent years are to increase the circuit density used in electronic systems and to increase the usage of optical waveguides for information transmission. For long-distance transmission of information, optical fibers are increasingly replacing conductive cables and wireless transmission systems. High device density is manifested as high circuit density in both microelectronic chips and printed wiring boards (hereinafter "PWB").

Electronic systems are generally organically constructed by mounting various system components on a PWB and interconnecting the PWB with circuit transfer elements known as backplanes. The backplane may include various socket elements to house the PWB.
The PWB is supported by troughs or shelves in a parallel arrangement so that the PWB contacts the socket when the PWB is inserted into the shelf. As printed circuit board circuit densities increase, it becomes increasingly difficult to provide the necessary backplane interconnects. This is because the impedance of the interconnection transmission line increases as it becomes thinner. In addition, the distance over which information must be transmitted by the backplane conductors is generally much longer than the distance transmitted by printed wiring boards. These factors reduce the speed at which the circuit can operate. As a result, the inherent advantages of high circuit density are lost.

In addressing these problems, it has been proposed to connect more electronic systems with optical fibers or other optical waveguides. For example, “Journal of Lightwave Technology (Journal
of Lightwave technology) ”, Vol.7, No.10 (1989
1530-1539 (issued in October, 2010),
A paper entitled "Glass Waveguide on Silicon for Optical Hybrid Packaging" by CH Henry et al. Defines a glass optical waveguide in a manner similar to optical lithographic definition of printed wiring. For that purpose, a method using an optical lithographic method is disclosed. Such "printed wiring" optical waveguides always have much greater losses than optical fibers. Therefore, such a waveguide is only practical for transmitting information over a short distance. Moreover, a sudden change in the direction of the optical waveguide inevitably causes considerable light loss. For this reason, it is difficult to use an optical waveguide to transfer light from one substrate to another.

[0005]

Accordingly, it is an object of the present invention to be readily used to efficiently transfer large amounts of information between circuit component boards, such as printed wiring boards, and to transfer such information. It is to provide a device capable of

[0006]

According to one embodiment of the invention, optical input and output elements are first provided on a corresponding common area near a first end of a flat substrate member such as a printed wiring board. The placement allows a large amount of information to be transferred between adjacent flat substrates. For example, the electronic output of a given PWB is translated by a laser source in a known manner into an optical output.
The photodetector constitutes the input element of each PWB. In some embodiments, the backplane members are then arranged to intersect the parallel array of PWBs. This causes one end of the backplane member to contact one end of each PWB at or near the common area containing the optical input and output elements. A plurality of arcuate grooves for supporting the optical fiber are provided in the optical backplane member. The arcuate groove connects each light output element of each PWB with all of the light input elements of the other PWBs.
Accordingly, the optical backplane member has an intricate array of arcuate grooves of varying depth. Each groove supports an optical fiber,
Such an optical fiber connects each light output element with all of the other PWB's light input elements.

Where each PWB comprises conventional electronic circuitry, each output source can be a laser source that converts an electronic signal into light and each input source can receive optical information from various sources in the PWB.
Can be a light-receiving element that converts to an electrical signal for processing by. If the transmission path on the PWB is an optical waveguide, the optical output is the output of such a waveguide. This output is then transmitted by an optical fiber to the input of the optical waveguide of another PWB. This optical waveguide constitutes the optical input.

Since the optical fiber has a low loss and a large bandwidth, a large amount of information is converted into light by a known method with a single laser source in order to be transmitted to various light receiving elements of other PWB by the optical fiber. be able to. The appropriate addressing means associated with each signal directs the information to the appropriate PWB, and then to the appropriate components of such PWB. The optical backplane member is arranged at 90 degrees with respect to the parallel array of PWBs, and each arcuate groove is formed to have a sufficiently large radius of curvature so that the optical fiber can be easily fitted into the groove. , Can convey information with minimal loss. Needless to say, optical fiber has much lower loss than PWB.

In another embodiment of the invention, each light output or light source is connected to the detector end of the backplane member by an optical fiber. As will be apparent from the discussion below, the backplane has an inherently complex interconnect arrangement.

Therefore, it is difficult to fix a broken or damaged optical fiber after mounting and operation. Providing the light source and detector terminals facilitates bypassing the broken connection portion of the backplane member by providing a "jumper" interconnect between the appropriate optical fibers of the light source.

In yet another embodiment of the present invention, the optical backplane member is arranged such that its large surface contacts the end of the PWB. The thickness of the optical backplane is PWB
It is thick enough to provide a sufficiently large radius of curvature for an optical fiber supported on a large surface opposite to. The optical fiber extends through an opening in the backplane member. Since more than one aperture can be provided for each PWB, the input and output elements of the PWB are each PWB.
Can be placed at two or more locations. A convenient way of implementing such an arrangement contributes to its practicality, as described below.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the drawings.

Referring to FIGS. 1, 2, and 3. here,
A parallel arrangement of printed wiring boards (PWB) 11A-11E is schematically shown. It contacts the optical backplane member 12 along one end of the PWB. The PWB has light emitting elements 13A-13E at one end and light receiving elements 14A-14E at the other end. The backplane 12 has a plurality of arcuate grooves 16. Each arcuate groove 16 connects the light emitting element 13 to one of the light receiving elements 14. Light emitting element 13A
-13E constitutes the optical output of the PWB, and the light receiving element 14A-
14E constitutes the optical input of each PWB.

FIGS. 1, 2 and 3 are only schematic and not to scale. It has also been significantly simplified to aid understanding. Therefore, in these figures, PWB 11A. Only the grooves associated with 11C and 11E are shown. The purpose of the groove 16 is to support the optical fiber. For clarity of illustration, this optical fiber is not shown in FIG. Further, in order to facilitate the understanding of the present invention, the groove 16 connecting the light emitting element 13E to the light receiving elements 14A and 14C is shown by a thick black line,
The groove 16 interconnecting the light emitting element 13A to the light receiving elements 14C and 14E is shown by a thick black line in the middle, and the groove 16 associated with the light emitting element 13C is shown by a bright thick line. Only a limited number is shown because it would be difficult to track the state of the interconnect if all the grooves were shown for all five PWBs. Therefore, although not shown in the drawing, the groove connects the light emitting element 13B to the light receiving elements 14A, 14C, 1
4D and 14E, the light emitting element 13D is connected to the light receiving elements 14A, 14B, 14C, and 14E, and the light receiving element 14B is connected to the light emitting elements 13A, 13C, and 13E.
D, and 13E, and photodetector 14
D is interconnected to light emitting devices 13A, 13B, 13C, and 13E.

FIG. 4 also shows a cross-section of a backplane member having multiple grooves 16 although the actual dimensions are different. A number of arcuate grooves converge at each light emitting and light receiving element, and in these areas, the grooves 16 are deep enough to accommodate a number of optical fibers 18 equal to the number of PWBs (ie, 5). Is formed.

The purpose of the arcuate groove is for each light emitting element 1 of each PWB.
3 to support the optical fibers interconnecting all the light receiving elements 14 of other PWBs. Again, for clarity, only a few fiber optic interconnection paths are shown in FIGS. 1 and 4. For example, as shown in FIGS. 4 and 1, the optical fiber 18A (see FIG. 4) interconnects the light emitting element 13A (see FIG. 1) with the light receiving element 14E,
It is supported by grooves 16A having different depths. Similarly,
As shown in FIG. 4, the optical fiber 18C includes the light emitting device 1
3C is interconnected with the light receiving element 14E, and the grooves 1 of different depths are connected.
It is supported by 6C. Many grooves 16 in FIG. 1 have different depths, the deepest point being the convergence point of the light emitting element and light receiving element areas. A large number of grooves intersect each other, and the optical fiber crosses over at the intersections, but such crossover causes no problem. This is because optical fibers are usually located at different depths.

The continuous separation of PWB 11 depends on these P
The arcuate optical fibers that interconnect the WBs are large enough that they do not have small radii of curvature that interfere with transmission. For example, increasing the loss of an optical fiber as the curvature increases is known as “Journal of the Optical Society.
Journal of the Optical Society of Am
erica) ”, Vol.66, No.3 (March 1976) 216-
D. Marcu, page 220
se), "Optical Fiber Curvature Loss Equation". The optical fiber is used as a bus transmission line for transmitting the output of each PWB 11A-E to the input of all other PWBs.

Each PW to convert electrical output to optical output
The apparatus used in B is shown in FIG. In FIG. 2, PWB1
1E has a plurality of electric transmission lines 20, which are directed to a processor 21 which controls a light emitting element 13E. Please refer to FIG. The processor 21 excites the laser 21. The laser emits light into a graded index rod lens 23 and then toward a fiber optic bundle 24 as shown in FIG. The fiber optic bundles of FIG. 6 are arranged in a vertical array held in place by a support member 25. The optical fiber 18 of FIG. 5 is then transferred to the other PWBs of FIG.
Is placed in the groove of the backplane member 12, as shown in FIG. Other light sources such as light emitting diodes (LEDs) can be used in place of laser 22.

The light-receiving elements 14A-E can be constructed in almost the same manner. However, the laser element 21 is replaced by a photodetector. This photodetector converts the incoming light energy into electrical energy and transmits it to the microprocessor. The microprocessor then properly distributes this electrical energy to the elements of the PWB. This is shown in FIG. The photodetector 22 'receives light from the graded index rod lens 23' and converts it into an electric signal, which is transmitted to the processor 21 'and distributed to the transmission line of the PWB. Appropriate holes through the PWB connect the side surface of the light receiving element to the side surface of the light emitting element.

Please refer to FIG. 8 and FIG. The support element 25 of FIG. 5 can consist of a pair of silicon elements 28,29. The device is engraved with a plurality of mating "V" grooves to hold the optical fibers 18 and 24. The support element 25 attaches the optical fiber 18 associated with the backplane member 12 to the associated optical fiber 24 of each PWB.
It can also be a fiber optic connector for interconnection to. Such connectors are known to those skilled in the art as Multiple Fiber Array (MAC) connectors. Various M's for aligning and supporting opposing optical fibers
AC connectors are disclosed, for example, in US Pat. Nos. 4,998,796 and 4,818,058.

The backplane member 12 is illustrated as having a socket arrangement for receiving and receiving the PWB 11.
This type of arrangement is used with existing electrical backplanes to help insert and remove PWBs. However, it is not always necessary to carry out the present invention. In short, the PW that forms the contact point with the backplane member 12
It is only necessary to have the light emitting element 13 and the light receiving element 14 in the common region of each PWB near the end of B. A conventional electrical backplane is typically 9 with respect to the plane of the backplane 12.
It is placed in a plane with an angle of 0 degrees. The reason the backplane extends in the direction shown is to support the optical fiber in such a way that the direction of the optical fiber need not be inadvertently changed. Therefore, the U-shaped arcuate groove can also be formed to have a sufficiently large radius of curvature at every location to avoid considerable loss by the optical fiber. If the backplane member 30 were bent at a 90 degree angle with respect to that shown, the optical fiber would also have to be bent abruptly, causing bending losses.

Collecting the complicated electric circuits of each PWB at one point,
It is a matter for a person skilled in the art to convert an electronic signal into an optical signal and transfer it into a single light beam. Generally, processor 2
1 adds address signals to various electronic signals. This electronic signal is converted into an optical signal. This address directs the signal to the proper destination after being detected by the optical fiber. Due to the high transmission capacity of optical fibers, a single fiber is sufficient for transmitting information between PWBs. It is also a matter for a person skilled in the art to convert an optical signal into an electronic signal by a photodetector and appropriately distribute it.

The construction of the backplane member 12 is complex because it has a large number of arcuate grooves of varying depths.
The present invention is useful with 6 or more PWBs forming a more complex groove assembly. Another advantage is that the backplane of the present invention can be mass-produced for use as a general purpose backplane for interconnecting various different types of PWBs. Therefore, in a given system, for example, PWB11E through PWB11B
There is no need to convey information to. However, the present invention has the ability to provide very flexible design freedom that can be used in any electronic system. The actual size of the optical fiber is very small. Generally, the diameter is 250 microns. Also, the package size of the light source such as a laser and the photodetector is extremely small, so that the system is not bulky. If a thin plastic coating is used, the optical fiber diameter can be as high as 140 microns. The backplane member 12 can be formed of plastic and can be inexpensively manufactured by injection molding. The optical fiber 18 may then be affixed to the backplane 12 for connection to the PWB assembly.

The original motivation for the present invention was to mitigate the PWB interconnect's reactivity and resistive losses that limit the operating speed of the system. Also, the same motive is for each PW
It also leads to the inclusion of an optical fiber in B. This attempt is being accomplished. In fact, all transmission lines of the PWB can be optical waveguides. In this case, it is not necessary to use a separate laser source or photodetector for the interconnection. That is, if the transmission lines 20 of FIG. 2 are optical waveguides, they can be directly coupled to the optical fiber 18 of FIG. The transmission lines on the PWB can obviously also be a combination of electrical and optical transmission lines.

Referring again to FIG. In addition to interconnecting PWBs, each light emitting element 13A-13E and light emitting element terminal 26
An interconnection path is formed between the light receiving elements 14A-14E and the light receiving element terminals 27. Please refer to FIG. The light receiving element terminal 27 exposes the optical fiber 18 connected to the PWB light receiving element, while the terminal 26 exposes the optical fiber 18 connected to the light emitting element. In operation, if any interconnection between any light emitting element and any light receiving element is damaged or destroyed, interconnect the appropriate terminal ends of light receiving element 27 and light emitting element 26. Can be easily connected and repaired. For example, refer to FIG. When the optical fiber 18A interconnecting the light emitting element 13A and the light receiving element 14E is accidentally destroyed, the optical fiber of the terminal 26 connected to the light emitting element 13A and the optical fiber of the terminal 27 connected to the light receiving element 14E are arranged, Alternate interconnections can then be formed by interconnecting these optical fibers with external optical fibers. This repair capability is more practical for securing optical fiber 18 within the backplane member. For example, after mounting the optical fiber 18, the groove 16 can be filled with an epoxy resin.

As explained above, the greatest use of the invention lies exclusively in the novel method of organizing the system. For example, all PWBs for different types of systems
It can be formed to have a light source and a light receiving element on the common area of the PWB. The same backplane member can then be used to form the interconnect, regardless of system requirements. The processor on each PWB provides the proper routing to achieve the system requirements.

Compared to conventional electronic backplanes, the optical backplane of FIG. 1 lacks compactness and takes up more space. Another drawback is that all optical inputs and outputs are
It must be placed on the same common area of WB. Please refer to FIG. 10 and FIG. These problems are mitigated by using the optical backplane member 32 to support multiple PWBs 31A-31C. One wide surface abuts the end of the PWB 31A-31C and the other wide surface supports the interconnect optical fiber 35, as shown in FIG. The optical fiber 35 is connected to the PWB's optical fiber 36 by a support element or MAC connector 25. This MAC connector may be the same as that shown in FIGS. 8 and 9. The PWB optical fiber 36 can be connected to the PWB at one or several points on the PWB.
It can be connected to a light source, a photodetector or an optical waveguide associated with B. As mentioned above, the photodetector converts the incoming light energy into electrical energy and the light source converts the delivered electrical energy into light energy. The optical fiber 35 can also be connected to an external circuit by a MAC connector 25A (preferably located near the periphery of the optical backplane member 34).

The optical backplane member 32 has the facing surface 3
It has a sufficient thickness between 3 and 34 to provide a suitably large radius of curvature. Each optical fiber has a surface 34 within this radius of curvature.
And the MAC connector 25 must be bent in making the connection. Typical dimensions of the backplane 32 are 8 inches x 16 inches x 3 inches (thickness). For digital transmission at practical power levels, the minimum radius of curvature that allows an optical fiber to bend without suffering significant loss is 1 inch. Although 3 inches thick is thicker than a typical electrical backplane, it does not add significant bulk to the device of Figures 1 and 2 and gives the optical fiber a sufficiently large radius of curvature to avoid substantial losses. You can FIG. 16 is an enlarged view of the opening 37 in the optical backplane 32. The optical fiber 35 extends through the opening 37. After the assembly is completed, the wall portion 38 of the opening 37 is rounded so that the curvature of the optical fiber can gradually become the proper radius. In addition to the optical fibers shown, the optical backplane member 32 also supports power and / or ground wires for the PWB. This is also true for the embodiment of FIG.

12-17 show a method of assembling the structure of FIGS. 10 and 11 according to the present invention. Referring to FIG. The first step is to form a suitable opening 37 in the optical backplane member 32. The optical backplane member 32 is, for example, solid plastic and has an opening 37.
Is a properly rounded wall surface 3 as described in FIG.
8 is formed.

Referring to FIG. The next step is to cover all openings with a "peelable" plastic sheet member 39, as shown. This "peelable"
For example, a plastic sheet member is KAPTON or MYLA
R. All of these are registered trademarks of DuPont. Although the peelable sheet is adhered to the optical backplane member 35, such adhesion is not permanent and can be manually separated from the member at will. Suitable adhesives include PHOTOMOUNT (registered trademark of 3M Company) and various silicone pressure sensitive adhesives. One end of each sheet member 39 is in the lower half of the MAC connector 28. This MAC connector corresponds to the member 28 of FIGS. 8 and 9. The member 28 regulates the arrangement of the V grooves. Each V-groove is suitable for supporting a single optical fiber. The intended path of the optical fiber is shown in FIG. The next step is to apply adhesive to all areas of the optical fiber member 35. This area is intended as part of the fiber optic path. This adhesive is a 500 or 600 series film adhesive commercially available from Bostik, Inc. and also covers the exposed surface of the peelable sheet member 39 and the connector 28.

Referring to FIG. Next, the optical fiber is M
An optical fiber is placed over the adhesive area 40 so as to extend into the AC connector portion 28. (For clarity, see FIG.
4, the adhesive 40 is not shown. ) Optical fiber 3
Although 5 can be placed on the adhesive by hand, it is preferably placed in the desired pattern using known methods of routing thin conductors. For example, US Pat.
Nos. 778 and 4541882 disclose a method for arranging densely packed fine copper conductor wires.

Referring to FIG. Next, an adhesive plastic encapsulation layer is placed over all optical fibers 35. The sectional view of FIG. 16 shows the adhesive layer 4 in this assembly process.
0, the peelable plastic sheet 39, the optical fiber 35, and the sealing layer 42 are shown. Finally, the upper portion of the MAC connector is mated with the lower portion 28 to form the connector element 25 shown in FIG. After peeling off the optical fiber and the peelable sheet from the optical backplane member, the connector element 25 is assembled. At this point, the adhesive 40 maintains the adhesion of the major portion of the optical fiber to the optical backplane member. After assembling the MAC connector 25, the connector is inserted into the opening 37 as shown in FIG. The remaining connector portion 28 is peeled back, assembled in a similar manner into a complete MAC connector and inserted into the adjacent opening 37. The optical fiber ends are then placed as known to those skilled in the art and each PWB 31A
Connect to the corresponding MAC connector at -31C to form a structure as shown in FIGS.

Referring to FIG. This shows another embodiment. After assembling the MAC connector 25 as shown in FIG. 17, this connector is mounted in a plastic housing 44 having a spring clip 45. Figure 1
After being "peeled back" in step 7, the optical fiber is drawn into the housing. The housing is then inserted into the opening in the optical backplane 32 until the stop 46 is reached. After the loading is completed through the opening, the spring clip 45 is opened to prevent it from moving to the left and, together with the stop 46, firmly holds the MAC connector 25 and the optical fiber 35 in the optical backplane 32. The mating MAC connector associated with the PWB optically couples the optical fiber associated with the PWB to the fiber 35.

In the embodiment shown in FIGS. 10 and 11, each PW is
Interconnects for B can be made at more than one location on the PWB. This provides significant design freedom for a given electronic device. Of course, in the embodiment of FIG. 1 as well, the input-output elements can be concentrated at one location on each PWB, if desired. The MAC connector 25A for the external circuit can be located anywhere on the backplane member and is slightly easier to use than the terminals 26 and 27 of FIG.

In the embodiment of FIGS. 10 and 11, a special optical fiber connection is provided for the MAC connector 25 and the external terminal (see FIG. 1).
And performs the same function as terminals 26 and 27 of FIG.
That is, between the broken fiber on the backplane and the terminal for a "jumper" connection that can be replaced).

[0036]

As described above, according to the present invention,
An apparatus that can be easily used to efficiently transfer a large amount of information between circuit component boards such as a printed wiring board and that can perform such transfer is realized.

[Brief description of drawings]

FIG. 1 is a schematic plan view of an optical interconnection device according to an embodiment of the present invention.

2 is a side view of the device of FIG. 1. FIG.

3 is a rear view of the device of FIG. 1. FIG.

4 is a schematic view of a groove for containing an optical fiber in the device of FIG.

5 is a schematic diagram of a light source that can be used in the apparatus of FIG.

FIG. 6 is a schematic diagram of an optical fiber bundle that can be used in the apparatus of FIG.

FIG. 7 is a schematic diagram of a photodetector that can be used in the apparatus of FIG.

8 is a cross-sectional view of a multiple fiber connector that can be used with the device of FIG.

9 is a sectional view taken along the line 9-9 in FIG.

FIG. 10 is a schematic view of an optical interconnection device according to another embodiment of the present invention.

11 is a view taken along the line 11-11 in FIG.

FIG. 12 is a view showing one of continuous steps in assembling the device of FIG. 11.

FIG. 13 is a diagram showing one of continuous steps in assembling the device of FIG. 11.

FIG. 14 is a diagram showing one of successive steps in assembling the device of FIG.

FIG. 15 is a diagram showing one of successive steps in assembling the device of FIG. 11.

FIG. 16 is a diagram showing one of continuous steps in assembling the device of FIG. 11.

FIG. 17 is a diagram showing one of continuous steps in assembling the device of FIG. 11.

FIG. 18 is a cross-sectional view of an apparatus that can be used to mount a MAC connector and associated optical fiber in an optical backplane member of the type shown in FIGS. 10 and 11.

[Explanation of symbols]

 11A-11E Printed wiring board 12 Optical backplane member 13 Light emitting element 14 Light receiving element 16 Bow groove 18 Optical fiber 20 Electrical lead 21 Processor 22 Laser 23 Graded index rod lens 24 Optical fiber bundle 25 Supporting member 26, 27 Terminal 28, 29 Silicon element 37 Opening 38 Curved wall 39 Sheet member 40 Adhesive

 ─────────────────────────────────────────────────── ————————————————————————————————————————————————— Inventor Muhammed Afzal Shahed United States 08638 New Jersey, Mercer County, Ewing Township, Lilac Drive 4

Claims (9)

[Claims] 1. A generally parallel array of first flat members (11), each member containing a plurality of conductors for transmitting electrical energy; each first flat member carrying an optical signal. Contains at least one light output element (13) capable of converting a signal; each first flat member comprises at least one light input element (14) capable of converting an optical signal into an electrical signal Each light input element and each light output element is disposed near the first end of the first flat member and is electrically coupled to a conductor of the first flat member. A second side that is generally lateral to the parallel array and is in physical contact with the first end of each first flat member.
A flat member (12); and a plurality of optical fibers (16) supported by said second flat member, at least a plurality of said optical fibers being interconnected to a number of input and output elements of said first flat member. Interconnecting device consisting of things. 2. The apparatus of claim 1, wherein each light output element comprises a light source and each light input element comprises a photodetector. 3. The second flat member has opposing generally flat first and second faces, each face having a length and a length substantially greater than a thickness dimension separating the first and second faces. Has a width dimension; the first surface of the second flat member contains the first end of the first flat member; the optical fiber is supported on the second surface of the second member; 3. The apparatus of claim 2, wherein the optical fiber extends through an opening (37) in the second flat member for contacting the light input and output elements of the first flat member; 4. The openings are defined by sidewalls extending through the thickness of the second member, each opening supporting at least one optical fiber without abruptly changing the orientation of the optical fibers. At least one rounded side wall
The device of claim 3 having a plurality. 5. The at least plurality of apertures extend through the second flat member near the junction with the first flat member; at least a plurality of optical fibers each
A first end extending through the opening for coupling with the first one light input element of the first flat member, and for coupling with the next one light output element of the first flat member. The device of claim 3 having a second end extending therethrough through another opening. 6. The second flat member has opposing generally flat first and second surfaces, each surface having a length and a length substantially greater than a thickness dimension separating the first and second surfaces. Has a width dimension; the end wall of the second flat member has a width equal to the thickness dimension and interconnects the first and second faces; the end wall of the second flat member has a first width Contacting the first end of the flat member of
The apparatus of claim 2 wherein the first and second faces of the second flat member are generally perpendicular to the first end of the first flat member. 7. At least certain ones of the optical fibers each connect an input optical element of one flat member and an output optical element of another first flat member to connect two first flat member 7. The device of claim 6 contained within an arcuate groove in a first surface of a second member extending therebetween. 8. The opposite end portion of each optical fiber is connected to another first flat member; each end portion of each optical fiber is relative to the first flat member to which this end is connected. 8. The device of claim 7, wherein the portions of each optical fiber between the opposing end portions have a generally U-shaped configuration. 9. The printed wiring boards each have a large first flat surface, the first flat surfaces being substantially parallel; the back surface having a large second flat surface, the flat surface extending over the entire first flat surface. 8. The device of claim 7 which is generally perpendicular to and extends through the entire first plane.