Optical connector

Abstract: An optical connector comprises an optical fibre connector ferrule which comprises a substrate plate having at least one optical fibre groove and pin grooves each being formed at one surface thereof, and a cover plate joined to the substrate plate to form at least one optical fibre groove holes into which an optical fibre is inserted; a guide pin means to be inserted into the pin grooves for coupling the optical fibre connector ferrule with another; and means for absorbing the variation in the diameter of the guide pins means.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a filiform material positioning connector, particularly to an optical connector that uses guide pins to couple optical connector plugs together for fixing optical fibres in position in lightwave communications systems. Prior Art Fig. 1 is a sketch of a typical example of the prior art optical connector. In Fig. 1, the numeral 10 denotes an optical connector ferrule formed by resin molding; a ribbon fiber (A) contains five optical fibers 15 which are fixed in position side by side at a pitch of, say, 0.3 mm, and guide pin holes 16 are formed on both sides of the ribbon fiber at a pitch of 3.6 mm. Indicated by 17 is a guide pin having a diameter of, say, 0.7 mm. Two such guide pins 17 are inserted into guide pin holes 16 formed in one optical plug ferrule 10, then inserted into the corresponding holes in the other plug which is positioned in registry with the first plug, and the two optical connectors are coupled together. In the present invention, the term "optical connector plug" is used to designate the most important basic member of an optical connector which fixes optical fibres in position so as to couple them together. When coupling multi-fiber optical plug 10, it is necessary that the optical fibers in one connector should abutt in a very precise manner against those in the other connector in order to minimize the coupling loss. This requirement is particularly stringent when coupling single-mode fibers which have a core diameter of only about 10 µm and even an axial displacement of no more than about 1 µm between fibers will cause a great coupling loss. To avoid this problem optical fibers to be mounted on an optical plug must be positioned in the proper place with very high precision; in coupling two optical connectors, it is also necessary that they should be positioned with high precision by means of guide pins. In order to realize low-loss coupling of multi-fiber optical connectors of the type described above, it is first of all necessary that optical fiber guide holes and guide pin holes should be provided at designed positions by precision machining. But even if this requirement is met, some clearance still remains both between the optical fiber guide holes and optical fibers and between the guide pin holes and guide pins and because of the existence of such clearance, it is not always possible to achieve low coupling loss. Even if the clearance is only about 0.5 µm both between optical fibre guide holes and optical fibres and between guide pin holes and guide pins, optical fibres will experience an axial offset of about 1 µm in an extreme situation. Therefore, in order to realize low coupling loss, it is essential that each of these clearances be entirely eliminated or substantially reduced to zero. However, in consideration of the variation in the inside diameters of optical fiber guide holes and guide pin holes, as well as the variation in the outside diameters of optical fibers and guide pins, it is by no means easy to reduce these clearances. If an optical fiber guide hole should have an inside diameter smaller than the outside diameter of an optical fiber to be inserted thereinto, not only is it impossible to insert the optical fiber but also the fiber itself may break. If the inside diameter of a guide pin hole is smaller than the outside diameter of a guide pin to be inserted thereinto, the guide pin, which must be forced into the guide pin hole, will break either itself or the guide pin hole. Suppose here the case where guide pins are to be inserted into guide pin holes in a multi-fiber optical connector. If the precision of machining is within ± 1 µm both for the guide pin diameter which should be 0.700 mm and for the inside diameter of the guide pin hole which should be 0.701 mm, there is a high likelihood that some of the guide pins have an outside diameter of 0.701 mm while some guide pin holes have an inside diameter of 0.700 mm. In this situation, none of the guide pins can be inserted into any guide pin hole. As described above, the efforts so far made to minimize the clearance that exists between guide holes and wire materials when the latter are to be fixed in position in the former have been limited by the precision of machining and this means that there is a certain limit on the effort toward reducing the coupling loss that occurs in coupling connectors such as multi-fiber optical connectors. Therefore, these problems have been a major obstacle to the goal of achieving low-loss coupling of optical connectors. With an optical connector of the type shown in Fig. 1, some clearance (g), as shown in Fig. 2, is necessary for permitting a guide pin 17 to be smoothly inserted into a guide pin hole 16 in an optical connector ferrule 10. However, the provision of this clearance (g) causes the problem that the coupling loss occurring in coupling optical connectors, in particular, those optical connectors which are used to achieve precise positioning of single-mode fibres with a core diameter of 10 µm, will vary as a result of repeated connect-disconnect cycles. Stated more specifically, if a variation of 0.5 µm occurs on account of the clearance (g) as a result of repeated connect/disconnect cycles, the optical connectors that were initially connected to produce a coupling loss of 0.5 dB will eventually produce a variation of about ± 0.3 dB after repeated connect and disconnect operations. This amount of variation is greater than the initial value of coupling loss. It is therefore clear that in order to realize low-loss and stable coupling of single-mode fibers, the connect/disconnect variation resulting from the clearance (g) for guide pins 17 must be reduced. However, if the clearance (g) is reduced, it becomes difficult to smoothly insert the guide pin 17 into the guide pin hole 16. These problems could be solved by employing a guide pin that is in the form of an elastic slit pipe 18 which has a longitudinal slit 18a as shown in Fig. 3. However, in order to fabricate a slit pipe having an outside diameter of 0.7 mm with a wall thickness of 0.1 mm, the pipe must be worked to have an inside diameter of 0.5 mm and it is difficult and very expensive to achieve by such micro-machining the precise working of the pipe to attain perfect roundness in its outside diameter and accuracy in other shape parameters. In order to reduce the size of an optical connector, the size of guide pins must also be reduced but to this end, the diameter of each guide pin has to be decreased to 0.5 mm and even to 0.3 mm, making the machining of an elastic slit pipe 18 more and more difficult. Document JP-58-88711 describes the manufacturing of a plastic connector comprising a base and a cover being provided with guide grooves for accommodating guide pins. When the guide pins are inserted into the guide grooves, the gaps between the pins and the grooves are filled with a silicone rubber. Finally, the base and the cover as well as the filled rubber are deposited with a metal for manufacturing a high-precision plastic connector. Furthermore, document EP-A-0 077 478 relates to an optical fiber connector being provided with identical connector halves both being provided with optical fiber accommodating grooves. For an improved positioning of the optical fibers in the grooves, the latter are provided with supporting rails being made from a soft metal. SUMMARY OF THE INVENTION An object of the invention is to provide an optical fibre connector that is free from the aforementioned problems. Another object of the invention is to provide an optical fibre connector which is equipped with guide pins that are reduced in diameter and which ensures high dimensional precision and can be produced in large quantities. A further object of the invention is to provide an optical fibre connector that tolerates a certain dimensional variation in working due to the limited percision of machining skill and that enables a wire material to be precisely positioned with reduced clearance. These objects are solved by an optical connector with the features of claim 1. Advantageous embodiments of the optical connector according to the present invention are defined in the dependent claims. The aforementioned object of the present invention can be achieved by providing an optical fibre connector having a filiform material positioning member in which a slit that runs substantially parallel to the axial direction and which communicates with the guide hole is provided either in part of the wall of the guide hole or in the vicinity of the guide hole. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sketch showing a typical example of the prior art optical connector; Fig. 2 illustrates the problem that affects the optical connector shown in Fig. 1; Fig. 3 is a perspective view showing an elastic slit pipe used as a guide pin; Figs. 4A, 4B and 5 are cross sections of a wire material positioning member according to the present invention; Fig. 6 is a perspective view of a wire material positioning member according to the present invention; Fig. 7 is a multi-fibre optical connector showing one example of the applications of the wire material positioning member of the present invention; Figs. 8A to 8C show various slit configurations that can be employed in the present invention; Fig. 9A is a perspective view of an optical fibre coupling member according to one embodiment of the present invention; Fig. 9B is a cross section of an optical fibre coupling member shown in Fig. 9A; Fig. 9C is a top view of the optical fibre coupling member shown in Fig. 9A; Fig. 9D is a side view of the optical fibre coupling member shown in Fig. 9A; Figs. 10A to 10C illustrate a technique for establishing direct silicon-to-silicon bonding; Fig. 11A is a perspective view of an optical connector according to one embodiment of the present invention in which part of the optical connector ferrule is cut out; Fig 11B is a cross section of Fig. 11A as seen in the direction indicated by arrows X 1 -X 1 ; Fig 11C is a top view of fig. 11A; Fig 12 is a side view showing one example of the guide pin used in coupling optical connectors. Figs. 13A and 13B illustrate an optical connector ferrule according to one embodiment of the invention into which guide pins have been inserted and which is equipped with a clamp mechanism, in which Fig. 13A is a longitudinal section and Fig. 13B is a top view; Fig. 14 is a longitudinal section of two optical connector ferrules that have been coupled together end to end by means of guide pins; and Figs. 15A to 15C show other embodiments of the area where the guide pin holes are exposed. Fig. 4A is a cross section of a filiform material positioning member according to one specific embodiment of the present invention as it is seen from the front side. The wire material positioning member is composed of a grooved substrate 501 having V grooves formed on its top surface and a flat holding plate 502, which are joined to form guide holes 503 in the interior of the assembly through which a wire material (A) is to be inserted. Each of the guide holes 503 is provided with four slits 504 that run substantially parallel to the axis of the guide hole 503 and which communicate with the same guide hole 503. The wire material (A) inserted into the guide hole 503 makes contact with the wall of the guide hole at three points (a), (b) and (c). At the lower points (b) and (c), the wire material (A) also makes contact with part of the two beams 505 that are defined by the four slits 504. Therefore, even if the outside diameter of the wire material (A) is slightly greater than the diameter of the circle that is internally tangent on the guide hole 503, the beams 505 that come in contact with the wire material will deform as shown in Fig. 4B, thereby allowing it to be smoothly inserted into the guide hole 503. In other words, the slits 504 permit the wall of the guide hole 3 to partly undergo elastic deformation and absorb any slight variation in the diameter of the wire material (A), thereby ensuring three-point supporting of the wire material without leaving any clearance from the guide hole 503. If desired, the bottom of each slit 504 may be rounded so as to inhibit the occurrence of cracking in this area. According to the present invention, slits 504 are provided either in a guide hole 503 or in the vicinity of this hole and the presence of such slits might deteriorate the overall strength of the positioning member. In particular, the beams 505 which are subject to a large amount of deformation might be affected by a bending stress that is exerted upon the base of the beams 505, or the vicinity of the bottom of slits 504. If a tiny initial crack occurs in this area during machining, it will later develop to a large crack that may eventually destroy the beams 505. Therefore, by rounding the bottom of each slit 504, the occurrence of initial cracking can be prevented to improve the overall strength of the positioning member. Fig. 5 is a cross section of a wire material positioning member according to another specific embodiment of the present invention as it is seen from the front side. As shown, some of the slits 504 are filled with a material 507 that has a different elasticity than the material of which the positioning member is made. This embodiment is effective for the purpose of changing the elastic strength of the beams 505. If an external force such as a bending stress is exerted upon the wire material (A) inserted into the guide hole 503, the stress will be propagated to the wall of the guide hole 503 but part of the transmitted stress is absorbed by the elastic deformation of the beams 505. In addition, the strength of the beams can be adjusted by the material 507 filled in the slits 504. Therefore, according to the embodiment shown in Fig. 5, the positioning member is capable of withstanding an external force without breaking and yet the beams can be adjusted to have a capability of undergoing an adequate amount of deformation. Fig. 6 is a perspective view of a wire material positioning member according to still another embodiment of the present invention. In addition to filling some slits with a certain material 507 as in the embodiment shown in Fig. 5, the strength of the beams 505 can also be adjusted by providing an additional slit 508 in a direction substantially perpendicular to the axis of the guide holes 503 as shown in Fig. 3. If more than one slit 508 is provided, the strength of the beam 505 that is present between adjacent slits 508 is determined by the distance from one slit 508 to another. Therefore, the slits 508 are also effective for the purpose of easily adjusting the strength of the beams 505. Example: Fig. 7 shows a multi-fiber optical connector which is one example of the application of the wire material positioning member of the present invention. The groove substrate 511 and the holding plate 512, which are the two principal components of the multi-fiber optical connector, are each made of silicon which, because of its hard and brittle nature, will not readily deform under external force. In the body of the connector, two guide pin holes 513 and five optical fiber guide holes 514 are formed, and guide pins and optical fibers are inserted into these guide holes 513 and 514, respectively, so that they can be fixed in position in these holes. Each of the guide holes 513 is provided with three slits 515 to define two beams 517 and each of the guide holes 514 is also provided with three slits 516 to define two beams 518. The guide pins 519 have an outside diameter of 0.35 mm and the optical fibres 520 have an outside diameter of 0.125 mm. The guide holes 513 and 514 are so designed that their inside diameters are smaller by a very small amount than the dimensions that permit free insertion of the guide pins 519 and optical fibers 520, respectively. The guide pins and optical fibers used in practice have tolerances for their outside diameters but these tolerances are on the order of ± 2 µm, which can be easily absorbed by the elastic deformation of part of the wall of the guide holes, namely, the beams 517 and 518. Therefore, the optical connector shown in Fig. 7 has the advantage that all of the guide pins and the optical fibers can be reliably supported at three points without leaving any clearance from the guide holes. In the example described above, silicon which is extremely resistant to deformation is used as the material of the wire material positioning member and if the guide holes were not provided with any slit as in the prior art, it would be entirely impossible for them to permit the insertion of a wire material whose outside diameter exceeds the inside diameter of these holes no matter how small the difference may be. However, the wire material positioning member of the present invention has no difficulty in absorbing a difference on the order of 2 - 3 µm and even a hard material like silicon becomes capable of undergoing a certain amount of deformation because of the provision of beams, thereby reducing the clearance between guide holes and the wire material to the smallest possible level. Compared with a prior art multi-fibre optical connector that had guide holes without slits and which produce an average coupling loss of 0.38 dB (on single-mode fibers), the multi-fiber connector of the present invention achieved an average coupling loss of 0.18 dB, and this demonstrates the fact that highly precise positioning can be accomplished by the present invention. It should be noted that the position of the slits to be provided in the wire material positioning member of the present invention is by no means limited to part of the wall of guide holes and the slits may be provided in any area in the vicinity of guide holes so long as the slits define beams that are capable of undergoing a small amount of deformation. Other parameters of slits, such as their number, width and depth, may also be set to any desired values. Figs. 8A to 8C show various slit configurations that can be employed in the present invention. In Fig. 8A, two slits 504 are provided distant form the guide hole 503. in Fig. 8B, a single slit 504 is provided distant form an asymmetric guide hole 503. Fig. 8C shows the case where slits 504 having different depths and widths are provided. In the above described embodiments, the material of the guide pin may be preferably made of ceramics, particularly of zirconia. The zirconia is tougher than alumina, and the outer diameter of the crystal thereof is not larger than 0.5 µm so that the surface thereof is smooth and slidable. Further, according to the present invention, at least one of the substrate and the holding plate may be made of silicon as, ceramics, in which the former may be different from the latter in material. The filiform material positioning member of the present invention offers the following advantages. (1) Even a filiform member that is slightly larger than the inside diameter of a guide hole can be inserted into that hole since the wall of the latter has the ability to deform. Any stress that is externally exerted upon the wire material that has been inserted into the guide hole can be relieved as a result of slight deformation that occurs in the wall of the guide hole. (2) If a positioning member is made of a hard and brittle material such as silicon, said member is highly prone to be nicked around the receiving edge of a guide hole when a wire material is being inserted into that hole. This problem is greatly mitigated in the positioning member of the present invention since the wall of a guide hole is capable of deforming in response to the insertion of a wire material. (3) The strength by which the wall of a guide hole can withstand deformation without breaking can be easily adjusted by various methods such as filling slits in the wall of a guide wall with a material that has a different elasticity than the material of which the positioning member is made, or changing the depth or width of the slits, or providing additional slits in a direction substantially perpendicular to the axis of the guide hole. (4) If the bottom of slits is rounded, they are rendered sufficiently resistant to cracking to prevent the failure of the positioning member. Figs. 9A to 9D illustrates a specific embodiment of the optical fiber coupling member of the present invention wherein a cover plate 312 placed on top of a grooved substrate 311 that has optical fiber guide grooves 313 and guide pin grooves 314 formed in its top surface is heated at an elevated temperature without employing any adhesive agent so as to produce a unitary assembly which has optical fiber guide holes 313' and guide pin holes 314' formed in its interior. A cutout 315 is formed in the rear portion of the cover plate 312 in such a way that part of the optical fiber guide grooves 313 becomes exposed to facilitate subsequent insertion of optical fibers. The grooved substrate 311 is joined to the cover plate 312 in the following manner. The surfaces of the two members at which they are to be joined together are ground and polished to high dimensional precision and direct bond is temporarily established by wringing; the combination is then heated to an elevated temperature, say, 1,000°C or more so that any impurities, water and other unwanted matter present at the interface between the two members are evaporated to activate their surfaces to such an extent that they are directly bonded together into a unitary assembly. For the theory of direct silicon-to-silicon bonding, see, for example, Denki Joho Tsushin Gakkai-shi (in Japanese), vol. 70, No. 6, p. 593-595, June 1987, which states as follows: "The surface of a silicon oxide film has OH groups that have been formed as a result of reaction with water. The surface of silicon is in the same state since it has a spontaneously formed oxide film present. If these OH groups are activated and brought into direct contact, hydrogen bonds will be formed (Fig. 10A). Upon further heating, the OH groups will undergo dehydrative condensation to produce Si-O-Si bonds (Fig. 10B). If the oxide film present in silicon-to-silicon bonding is extremely thin, oxygen will diffuse into the bulk of silicon, thereby forming Si-Si bonds (Fig. 10C). As shown in Figs. 9A to 9D, a cover plate 312 which is typically made of silicon is joined to a grooved substrate 311 that may also be made of silicon and which has optical fiber guide grooves 313 and guide pin grooves 314 formed in its top surface by machining so as to provide an assembly having optical fiber guide holes 313' and guide pin holes 314' formed in its interior. The portion of the cover plate 312 which lies over the rear part of the optical fiber guide grooves 311 is removed to form a cutout 315 so that optical fibers can be easily inserted into the optical fiber guide holes 313'. On the other hand, the portion of the cover plate 312 which lies over the guide pin grooves 314 is not removed so that an adhesive agent 318 which is injected in order to securely fix optical fibers in the optical fiber guide holes 313' and grooves 313 will not flow into the guide pin grooves. In one specific embodiment of the present invention, optical fiber guide holes are formed by simply joining a grooved substrate and a cover plate. Therefore, optical fibers can be easily inserted and assembled to provide a coupling member that is capable of positioning optical fibers with dimensional precision. In accordance with a specific embodiment of the present invention a cutout is provided by removing the portion of the cover plate which lies over the rear part of the optical fiber guide grooves and this allows optical fibers to be easily inserted into the optical fiber guide holes. If, in this case, the portion of the cover plate which lies over the guide pin grooves is left intact (i.e., remains bonded to the grooved substrate), it can be ensured that an adhesive agent used in order to fix optical fibers will not flow out of the system or flow into the guide pin grooves. According to a further embodiment of the invention as shown in Figs. 11A to 11C, part of the optical connector ferrule 401 is cut out so that part of the guide pin holes 402 is exposed in that area indicated by 403. When two optical connectors are coupled together with guide pins inserted into such partly exposed guide pin holes 402 in the connector ferrule 401, the guide pins will also become exposed in the area 403 where the guide pin holes are exposed. Fig. 12 is a side view showing one example of the guide pin 404 used in coupling optical connectors according to the present invention. As shown, the guide pin 404 is provided with a recess 405 in that portion which is to be situated in the area 403 when it is inserted into a guide pin hole 402 in the connector ferrule 401 shown in Figs. 11A to 11C. The guide pin 404 can be secured in position by causing a clamp mechanism to act in the recess in the manner to be described later in this specification. It is not always necessary to provide the recess 405 and if it is not provided, the guide pin may be clamped by allowing the necessary amount of lateral pressure to act on the pin. Figs. 13A and 13B illustrate a specific embodiment of the ferrule of the present invention into which guide pins have been inserted and which is equipped with a clamp mechanism. Fig. 13A is a longitudinal section and Fig. 13B is a top view. In the embodiment shown in Figs. 13A and 13B, the optical connector ferrule 401 is provided with a flange 406 in its rear portion and this flange 406 has a clamp mechanism as an integral part thereof. Stated more specifically, the top of the flange 406 provides an elastic beam 407 from which a plunger 408 projects downwardly. By exerting pressure on the elastic beam 407, the plunger 408 moves downward until it contacts the bottom of the recess 405 in the guide pin 404. According to this specific embodiment of the present invention, the optical connector is disconnected after the plunger has been urged into contact with the bottom of the recess 405, so the guide pins 404 are always left behind in the connector ferrule that has this urged elastic beam. Fig. 14 is a longitudinal section of two optical connector ferrules 401a and 401b that have been coupled together end to end by means of guide pins 404. As shown, the connector ferrules 401a and 401b are equipped with flanges 406a and 406b having elastic beams 407a and 407b, respectively. The elastic beam 407a shown on the right-hand side of Fig. 14 is urged downward to bring the plunger 408a into contact with the bottom of recess 405a in the guide pin 404. On the other hand, the other elastic beam 407b is not urged, so the plunger 408b remains distant from the bottom of the other recess 405b in the guide pin 404. If the connector ferrule 401a under this condition is disconnected from the other ferrule 401b, the guide pin 404 is sure to be left behind in the ferrule 401a which is shown on the right-hand side of Fig. 14. Figs. 15A to 15C show other embodiments of the area where the guide pin holes are exposed. Fig. 15A shows an optical connector ferrule in which a silicon top plate 411 is stacked on a grooved silicon substrate 410 having optical fiber guide grooves and guide pin grooves formed in its top surface and the two members are joined together with an interposing thin layer of an adhesive agent so as to form optical fiber guide holes 413 and guide pin holes 412. As shown, cutouts 414 are formed in part of the top plate 411 so that part of the guide pin grooves is exposed in those areas, and plungers are caused to move downward in such a way that they contact the bottom of the exposed areas 414 to clamp the guide pins. Fig. 15B shows an embodiment in which an optical connector ferrule is formed by joining a grooved silicon substrate 410 and a top silicon plate 411 as in the case shown in Fig. 15A. In this embodiment, part of the guide pin holes 412 is made exposed by entirely removing the rear portion of the top plate 411. A step portion 415 provided in the rear portion of the grooved substrate 410 serves as an area for fixing an array of optical fibers in position. Fig. 15C shows the case of employing a guide pin 404 that is longer than the optical connector ferrule; in this embodiment, the portion 416 that projects form the rear end of the ferrule is used as the area where the guide pin is exposed. For this particular embodiment of the optical connector of the present invention an area where guide pin holes are exposed is provided in part of the optical connector ferrule in such a way that the guide pins will become exposed in this area. If this configuration is combined with a clamp mechanism, the operator can disconnect and connect optical connector ferrules while having exact knowledge as to in which ferrule the guide pins have been left behind. An example of the clamp mechanism that performs its function by exerting pressure is shown in Figs. 13A, 13B and 14 but depending upon the specific use or dimensions of the connector ferrule, various modifications can be made without departing from the scope of the present invention by introducing some special features into the design of the flange to be mounted on the ferrule or of the housing of the connector plug. As described above, according to the present invention, the clearance that would occur between the guide pins and the guide pin holes which are to be coupled thereto is entirely eliminated or reduced to a very small value, thereby realizing low-loss coupling of optical fibers in a consistent manner. Further, the optical connector ferrules of the present invention can be precisely and easily disconnected or connected.

Claims: An optical connector comprising: an optical fiber connector plug which comprise a substrate plate (501) having at least one optical fiber groove and pin grooves each being formed in one surface thereof, and a cover plate (502) joined to said substrate plate to form pin groove holes (503) and at least one optical fiber groove hole into which an optical fiber is inserted; pin means to be inserted into said pin groove holes for coupling said optical fiber connector plug with another; and means for accommodating variation in the diameter of said pin means and of said at least one optical fiber, characterized in that said substrate and cover plates (502) are made out of a hard material such as silicon or a ceramic to aid positioning of said at least one optical fiber and said pin means; said cover plate (502) having a substantially flat planar surface facing said substrate (501); at least one of said at least one optical fiber groove and said pin grooves is provided with at least one slit (504) which runs substantially parallel to the axial direction of its respective groove, said at least one slit forming part of its respective groove and being arranged to define at least one cantilever-like flexible beam member (505) which serves as said accommodating means, whereby the fibre is supported at three points about its circumference. An optical connector as claimed in claim 1, in which said pin means is made of ceramics. An optical connector as claimed in claim 1, in which said pin means is made of zirconia. An optical connector as claimed in claim 1, in which at least one of said substrate and cover plate is made of silicon. An optical connector as claimed in claim 1, in which at least one of said substrate and cover plate is made of ceramics. An optical connector as claimed in claim 1, in which said cover plate is chemically bonded to said substrate plate without an adhesive material. An optical connector as claimed in claim 6, in which said cover plate and said substrate plate are made of silicon, the former being joined to the latter with Si-o-Si bonds. An optical connector as claimed in claim 5, in which said cover plate and substrate plate are made of silicon, the former being joined to the latter with Si-Si bonds.

Inventors: KAKII TOSHIAKI, SAITO KAZUHITO, SUZUKI SHUZO, KAKII, TOSHIAKI, SAITO, KAZUHITO, SUZUKI, SHUZO, Kakii, Toshiaki, c/o Yokohama Works of Sumitomo, SAITO, KAZUHITO, C/O YOKOHAMA WORKS OF SUMITOMO, Suzuki, Shuzo, c/o Yokohama Works of Sumitomo
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO ELECTRIC INDUSTRIES LIMITED
Application year: 1991
Main classification: G02B6
IPC codes: G02B6