Abstract: A fused fiber optic 1.times.4 or 2.times.4 coupler in which four optical fiber segments (A, B, C, D) extend longitudinally beside each other in a coupling region in which the fiber segments are at least partially fused together to form an assembly exhibiting a close packed cross section in which the fiber cores (11) are centered substantially at the corners of a four sided polygon having a pair of opposite internal acute angles substantially less than 90.degree..

Abstract: An optical fiber coupler package comprising an base member having a longitudinal groove disposed therein, and a cover member for the base member, wherein the cover member is shorter in length than the base member and wide enough to completely overlap the groove when placed so as to cover the base member.

Abstract: A method and device is provided wherein a reinforcement is provided for one or more optical fibers. One or more fibers are inserted into a sleeve made of a material that is substantially the same as the material of the cladding of the one or more optical fibers. The bore of the sleeve is sized to accommodate the one or more optical fibers; After the one or more optical fibers is inserted into the sleeve sufficient heat is applied to the sleeve for a duration to collapse the sleeve onto the one or more optical fibers. Preferably, the sleeve is a glass pre-form consisting substantially of 90% or greater silica.

Abstract: A hermetically sealed fiber optic coupler for packaging end joined optical fibers. The device includes at least one first optical fiber having a glass-based portion having a first free end and a second optical fiber having a glass-based portion having a second free end joined to the first free end of the glass-based portion of the first optical fiber to form an end joint. The device further includes an outer chamber having at least one open end, the outer chamber surrounding the end joint, the outer chamber and the end joint being hermetically sealed with a thermosetting plastic. In the preferred embodiment, the device also includes a primary tubular sleeve, positioned between the end joint the outer chamber; epoxy for tacking the glass-based portions of the first and second optical fibers to the primary tubular sleeve; and thixotropic epoxy for hermetically sealing the ends of the primary tubular sleeve.

Abstract: A composite optical fiber including a first optical fiber having a first core with a first diameter being optically fused to a second optical fiber having a second core with a second diameter that is smaller than the first diameter. The first optical fiber has an output end with a tapered end section. The first core tapers down in diameter in the tapered end section from the first diameter and terminates at the output end with a third diameter that is smaller than the first diameter and substantially equal to or smaller than the second diameter. The second fiber has an input end that is optically fused to the output end of the first fiber. The composite optical fiber of the present invention is formed by heating the output end of the first optical fiber, and then pulling the output end of the first optical fiber to form the tapered end section. The output end of the first optical fiber is then optically fused to the input end of the second optical fiber.

Abstract: The present invention provides a connecting member for facilitating connecting of optical fibers, and a connecting method in which the loss due to connecting is small. An optical fiber connecting member is composed of: a retaining portion having through-holes each of which has an inner diameter slightly larger than the outer diameter of optical fibers to be connected; and introduction portions which are integrally formed with and on the opposite end sides of the retaining portion and each of which has introduction grooves communicated with the through-holes to thereby make it easy to insert ends of the optical fibers into the through-holes. Further, the inner diameter of each of the through-holes is reduced by heating the connecting member to thereby make axis alignment of the optical fibers automatically to obtain connecting in which the connecting loss is reduced.

Abstract: A method (38) for packaging a microelectronic device (10) and a device (10) packaged by the method (38). The method (38) includes a step of providing (42) a first material (16) on an active surface of the microelectronic device (10). The first material (16) has a first temperature coefficient of expansion. The method (38) also includes steps of heating (46) the microelectronic device (10) and the first material (16) to a predetermined first temperature and molding (48) a second material (20) about the microelectronic device (10) and the first material (16). The second material (20) has a second temperature coefficient of expansion less than that of the first material (16). A final step of cooling (50) the first material (16), the second material (20) and the microelectronic device (10) provides a packaged microelectronic device (30).

Abstract: An optical device module comprises a module body including an optical device, a first fiber connector holding a first optical fiber, coupled to one end of the optical device, and a second fiber connector holding a second optical fiber, coupled to the other end of the optical device; and an enclosure body integrally molded with a resin such as an epoxy resin, an urethan resin to coat the module body. Almost the whole module body is coated with the integrally molded epoxy resin, so that the module body is protected efficiently from external heat, moisture, mechanical shock etc.

Abstract: An optical coupler to be used for optical telecommunications is disclosed, characterized by portions of exposed optical fiber sections located immediately adjacent to and outside the respective clots of the first adhesive agent as viewed from the welded optical fiber section being coated by a third adhesive agent having a Young's modulus smaller than that of the first adhesive agent.

Abstract: An improved fiber optic connector for supporting therebetween an array of optical fibers, the connector comprising first and second support members, each having on a first surface thereof a parallel array of grooves and at least one side landing section. The side landing section of the support member is substantially planar and has a substantially irregular surface thereon for enhancement of bonding between the support members. The grooves of the first and second support members are adapted to contain therebetween the array of optical fibers. The irregular surfaces of the side landing sections of the first and second support members are juxtaposed to substantially overlap each other when the first and second support members are placed in mating relationship around the array of optical fibers. The irregular surfaces of the side landings are joined together around the array of optical fibers with an adhesive epoxy.

Abstract: A method for manufacturing an optical RF bandpass filter comprises the st of: (1) mounting an optical fiber having first and second ends in a fiber support structure having first and second surfaces so that the first end is exposed at the first surface and the second end is exposed at the second surface; (2) forming a first layered mirror structure on a first substrate to create a first mirror wafer structure having a first reflective surface; (3) forming a second layered mirror structure on a second substrate to create a second mirror wafer structure having a second reflective surface; (4) affixing the first reflective surface of the first mirror wafer structure to the first surface of the fiber support structure; and (5) affixing the second reflective surface of the second mirror wafer structure to the second surface of the fiber support structure.

Abstract: An optical fiber which has an end surface E is inserted into a ferrule, then the end surface E is allocated into a hollow of the ferrule.After the optical fiber and the ferrules are united, the hollow is filled with ultraviolet ray setting resin whose refractive index is matched with the optical fiber.Then, the hollow is covered with a quartz glass, and ultraviolet ray is irradiated to ultraviolet ray setting resin through the quartz glass. So, the optical fiber, the ferrule, the ultraviolet ray setting resin and the quartz glass are unified.

Abstract: A mass-producible optical attenuation fiber assembly is provided with a first optical fiber with a predetermined attenuation, a second optical fiber connected to a first end of the first optical fiber and a ferrule for fixedly holding the other end of the first optical fiber. In this optical attenuation fiber assembly, the first optical fiber is doped with impurities to achieve a predetermined first attenuation and shortened to obtain a predetermined second attenuation. In the optical attenuation fiber assembly, the second optical fiber may also be cut to a fixed length and the cut edge portion of the second optical fiber may be fixed to another ferrule and polished. The latter ferrule is coupled to the former ferrule through an alignment sleeve.

Abstract: A light branching and coupling device excellent both in transmitting performance and in distributing performance in which the intermediate portion of an optical fiber 10a (10b) is thermally drawn to form light transmission fiber portions 11a and 15a (11b and 15b) and a light branching and coupling fiber portion 13a (13b) having a diameter smaller than that of the light transmission fiber portions and, at the same time, form tapering fiber portions 12a and 14a (12b and 14b) between the light transmission fiber portions and the light branching and coupling fiber portion so that the tapering fiber portions are tapered off gradually toward the light branching and coupling fiber portion 13a (13b) side. The light branching and coupling fiber portions 13a and 13b thus formed are fused with each other.

Abstract: The present invention relates to a package in which an optical waveguide module is mounted, at least having such structure as to reduce influence of expansion or contraction (thermal stress) of a metal housing, caused with a temperature change of the external environment and applied on junction parts between an optical waveguide substrate and members for fixedly supporting tip portions of input and output optical fibers. This package comprises a cavity for housing the whole of the optical waveguide module as covered with a buffer protection material, and a metal housing having through holes for leading the above optical fibers to the outside. Particularly, the optical fibers and the through holes are bonded and secured with a filler having higher airtightness than the buffer protection material and having a lower tensile modulus than a metal material forming the housing.

Abstract: A method for tuning fiber optic coupler and wavelength division multiplexer devices comprises the steps of fusing optical fibers having a refractive index responsive to ultraviolet radiation to form a coupling region having a coupling ratio dependent upon the refractive index, and subjecting the coupling region to ultraviolet radiation to adjust the coupling ratio to a predetermined value at a given operating wavelength.

Abstract: Apparatus for forming a refractive index grating in a waveguide in accordance with the invention includes a waveguide formed from a material that changes its index of refraction when exposed to a beam of optical radiation, a source of coherent optical radiation for forming a beam of radiation, a mirror arranged to intercept a first part of a beam and to reflect the first part of the beam through an angle, and a phase delay plate arranged to intercept a second part of the beam for delaying the second part of the beam propagating through the plate, in which the mirror and the phase delay plate are arranged so that the first part of the beam and the second delayed part of the beam form an interference pattern on the waveguide for changing the index of refraction of the waveguide, in a pattern corresponding to the interference pattern for forming an index grating in the waveguide.

Abstract: In a case where an arrayed optical fiber coupler obtained from a tape ribbon 1 is fixed to an reinforcement case 3, a glass portions 2b as a non-elongated portion outside of the elongated portions 2c of the coupler and a protection coating layers 2a at the back thereof are fixed to the reinforcement case 3 with an adhesive layer 4. A collectively coating resin layer 1a of the tape ribbon 1 is not fixed to the reinforcement case 3. The resin layer 1a is fixed to the reinforcement case 3 with a soft adhesive layer 5 different from the above adhesive layer 4, if necessary. As the resin of the adhesive layer 4, there is preferable an adhesive having the viscosity of 50 to 200 P and thermosetting property in addition to ultraviolet cure property.

Abstract: This invention relates to an optical waveguide module having stable temperature characteristics and moist heat characteristics even in a severe environment. This optical waveguide module includes a waveguide component having an optical waveguide on a waveguide substrate made of silicon or silica glass as the first material, and a ferrule made of a plastic material as the second material. An end face of an optical fiber is fixed by adhesion while it is inserted in a through hole of the ferrule, the through hole having a continuous inner wall. This ferrule is fixed with an adhesive having a predetermined strength so that its the end face opposes the end face of the waveguide component. The second material satisfies a relationship:.vertline..DELTA.L/(E.sub.1 /E.sub.2).vertline.<3.0.times.10.sup.-6 (.degree.C..sup.-1)with respect to the first material forming the waveguide substrate, where .DELTA.L is a difference in thermal expansion coefficient between the first material and the second material, E.sub.

Abstract: The arrangement for coupling optoelectronic components and optical waveguides to one another includes a carrier substrate (11); at least one optoelectronic component (9) or one optical waveguide (1) secured on the carrier substrate (11) and at least one lens (8) provided with an essentially planar surface and a spherical surface located opposite the essentially planar surface. The carrier substrate is provided with a depression (5) for a lens (8) having walls and the lens (8) is inserted into the depression (5) so that the lens (8) rests with its spherical surface contacting the walls of the depression (5) at at least 3 points and is rotatable about its spherical curvature center point. An adjustment device for rotatably positioning the lens (8) in the depression and a method of securing the lens in position after an adjustment are described.

Abstract: Overclad fiber optic couplers are made by inserting the uncoated portions of a plurality of optical fibers into the bore of a glass tube, collapsing the tube midregion onto the fibers and stretching the central portion of the tube midregion. The present method utilizes a glass tube the bore of which includes a circular portion and a recess. A plurality of optical fibers are sequentially inserted into the tube by threading the coated end into the circular bore portion until the uncoated portion of fiber is centered in the tube. The uncoated portion of fiber is then transferred laterally into the bore recess. After all fibers have been threaded into the circular bore portion and transferred to the recess, a filler fiber is inserted into the circular bore portion. The resultant coupler exhibits low excess loss.

Abstract: An apparatus for selecting waveguide modes in optical fibers is disclosed, which comprises an optical fiber having of a core and a cladding sheathing the core. The optical fiber has a selected portion of the cladding removed and forms a recessed space in the cladding while preserving a predetermined thickness of the cladding remaining covering the core. The optical fiber is selected for allowing the transmission of light having multiple waveguide modes with radial and azimuthal electric field components. The apparatus further comprises a birefringent material filled in the recessed space. The birefringent material has the first and second refractive indices and the first refractive index is larger than the core index of the optical fiber, while the second refractive index is smaller than the cladding index of the optical fiber.

Abstract: A method for producing a hybrid integrated optical circuit which utilizes a molding tool having holding devices for an electrooptic semiconductor component and negative molds for a waveguide trench and holding devices for an optical waveguide. The holding devices of the molding tool adjust the electrooptic semiconductor component with respect to the negative mold of the waveguide trench during reshaping with a polymer. The basic unit produced consists of the electrooptic semiconductor component, which is adjusted with respect to the waveguide trench molded in the polymer. Adjoining the waveguide trench are holding devices, which are molded in the polymer and by means of which an optical waveguide can be coupled to the waveguide trench in a self-adjusting fashion. The basic unit and the optical waveguide are permanently connected to one another with the aid of a cover, the waveguide trench being filled with an optically transparent material, as a result of which a waveguide is formed.

Abstract: Optical coupling between the end of a laser (10) mounted on a silica motherboard (12) and an optical fibre (11) is effected with the aid of a silicon platform (14) to which the end of the fibre (11) is secured. The motherboard (12) and fibre platform (11) are crystallographically etched to provide complementary mating profiles with a clearance of less than 10 .mu.m when alignment is established. While that alignment is maintained, resin (23) is introduced between motherboard and the fibre platform, and is cured. The minimal thickness of the cured resin minimises misalignments caused by resin shrinkage.

Abstract: A varied ratio coupler, and a method of forming the same, constructed and arranged, in a unitary structure, to cause optical power in an input optical fiber to couple asymmetrically to at least two output optical fibers in a manner establishing different insertion losses between the input fiber and at least two output optical fibers. The coupler includes a central fiber surrounded by a close-packed ring of fibers. In certain preferred embodiments, the coupler has a bend that lies in a preselected plane and has a radius of curvature that is selected to provide the above difference in the insertion losses.

Abstract: A method resulting in a package for a fiber optic component includes positioning the fiber optic component within a primary protective body. A flat wrappable secondary protective material having an adhesive on one side thereof is then wrapped around the primary protective body a plurality of times. The flat wrappable secondary protective material may be marked prior to wrapping the primary protective body. The adhesive on the flat wrappable secondary protective material may include a pressure sensitive adhesive allowing the primary protective body to be unwrapped.

Abstract: The fibers are connected to the component by adhesive means comprising a plurality of drops (11.sub.i, 12.sub.i) of an adhesive product, each of them fixing to the component between 1 and (N-1) adjacent fibers of the array, each of these drops being non-contiguous with at least one other of these drops, and at least one of the drops being longitudinally and laterally offset with respect to at least one other drop of the plurality.

Abstract: Overclad fiber optic couplers typically include an elongated glass body having a solid midregion through which at least two glass optical fibers extend in optical signal coupling relationship. At each end of the midregion is an end region containing a bore from which optical fiber pigtails extend. In accordance with the invention, each end region includes a first projecting portion, one surface of which forms a ledge. That end of each bore opposite the midregion terminates at a recessed face that intersects the respective ledge. One end of at least the first fiber extends from the first bore. That portion of the first fiber outside the first bore has a coating that extends along the ledge, the coating terminating outside the first bore. A mass of glue extends between the ledge and the recessed face and encompasses the bare portion of the first fiber that extends along the first ledge and at least a portion of the first coating that extends along the first ledge.

Abstract: An optical device, e.g. a signal generator adapted to provide an optical signal to a fibre tail or to a socket adapted to receive a fibre tail, is assembled by two thin films of adhesive. One film is normal to the beam path and, preferably 50-200.mu. thick. The other film is parallel to the beam path, e.g. surrounding the beam path, and preferably 30-90.mu. thick. Conveniently the device includes an intermediary component and end of said film adheres one of said components to said intermediary component.

Abstract: Signal energy in an installed optical fiber is extracted without using a physical connector, by an improved process in which the fiber is bent to within a prescribed range of angles, then controllably heated, and thereafter controllably cooled. The resulting structure exhibits relatively low permanent stress. A fiber end conventionally placed at the bend point receives unusually useful amounts of optical signal which can be routed to optical branch circuits in, for example, a building or a LAN.

Abstract: There is disclosed a coupling structure of optical fibers and optical waveguides, comprising optical fibers; an optical fiber arranging connector having a first and second members, the optical fibers being sandwiched by the first and second members to be fixed in the optical fiber arranging connector; a waveguide device having a waveguide substrate, optical waveguides being formed on a surface of the waveguide device, ends of the waveguides and ends of being aligned with each other by abutting end faces thereof against each other; an adhesive interposed and set between said end faces, the adhesive being a photo-setting adhesive, the first member being made of a material preventing light having a wavelength capable of setting said adhesive from passing therethrough, and in at least part of a region where the end faces of the optical fiber arranging connector and the waveguide device oppose to each other, at least one of the optical fiber arranging connector and the waveguide device in the vicinity of the end f

Abstract: A narrowband twisted optical fiber wavelength division multiplexer ("WDM") and a method for fabricating the WDM. The WDM includes a twisted pair of first and second optical fibers that are fused together, each of the first and second fibers having a first and second end. In the WDM, when a first and second light are applied to the first end of the first fiber, they will appear on the second end of the first fiber and the second end of the second fiber, respectively. When the first light enters the second end of the first fiber, and the second light is applied to the second end of the second fiber, they will both appear on the first end of the first fiber.

Abstract: A housing for fiber optic components reduces stress on optical fibers and protects the components from environmental shock and vibration. The housing includes a protective body having a receiving space wherein the fiber optic component is positioned. A rigid adhesive applied to the fibers in a specific stress reducing profile near the ends of the receiving space secures the component out of contact with the wall of the receiving space without inducing stress on the jacketless optical fibers. A gel support material fills the receiving space surrounding the component and providing vibration isolation. The invention is particularly uses for housing fiber optic couplers which are subject to shock, vibration, and temperature extremes.

Abstract: A star coupler for interconnecting optical fibers to distribute optical signals. The method for fabricating the star coupler comprises the steps of preparing a tubular member and first and second groups of optical fibers having bare fiber portions extending from the ends. The bared fiber portions of the first and second groups of optical fibers are inserted into the tubular member, in the opposite directions, in an end-to-end abutting relationship. The contacting ends of the bared fiber portions are then molten and fused together. The fused fiber portions are finally stretched together with the tubular member. It is possible to preheat the tubular member at a relatively low temperature so that the tubular member shrinks relative to the bared fiber portions to retain the latter. The obtained star coupler comprises first and second groups of optical fibers inserted into a tubular member in an end-to-end abutment relationship, with the ends joined together.

Abstract: A coaxial optoelectronic mount is provided. A coax cable having an inner conductor, an outer conductor, and an insulating region therebetween, and an end is formed. The end of the coax cable exposes portions of the inner conductor, the outer conductor, and the insulating region. A photonic device having a working portion, a first contact, and a second contact is mounted on the end of the coaxial cable. An optical fiber having a core region with a refractive index, a cladding region with a refractive index, and a surface is aligned to the working portion of the photonic device. An optical gel having a refractive index is disposed on the surface of the optical fiber and on the working portion of the photonic device operatively coupling the core region of the optical fiber to the working portion of the photonic device.

Abstract: It is an object of the present invention to provide an optical waveguide module in which, under the high temperature and high humidity, degradation of characteristics does not occur and which has strength to the oscillation, simple structure, and high reliability. A module unit 30 is formed by bonding a connector 32 provided at one end of a single-optical fiber cable 22 and a connector 31 provided at one end of a ribbon optical fiber cable 21 at both ends of a waveguide substrate 35 having a 1.times.4 branch optical waveguide by an adhesive having light transmission properties. The module unit 30 is provided in a housing 10, and at least a connecting portion between the optical waveguide and the optical fiber cable is covered with the resin contained in the housing 10. The housing 10 is sealed with a cover unit 15, and the single-optical fiber cable 22 and the ribbon optical fiber cable 21 are tightly inserted into a respective hole at end walls of the housing 10 and led out to the outside.

Abstract: A multiple optical fiber connector is constructed from a unitary planar substrate having two surfaces with 1) multiple fiber holes and 2) plural alignment regions located in opposing relationship to each other along edges of the substrate, the multiple fiber holes and plural alignment regions being formed substantially perpendicular to and between the surfaces of the substrate using photolithographical techniques. Each optical fiber is permanently mounted through one of the holes in one surface of the substrate so that the end of each fiber is substantially flush with the other surface of the substrate. Alignment posts which are positioned against the alignment regions and mounted substantially perpendicular to the surfaces of the substrate are used to align optical fibers mounted in the substrate with optical fibers mounted in a substrate of a mating connector.

Abstract: The present relates to the protective structure for an optical fiber coupler made from bare fiber parts of a plurality of optical fibers therein, the bare fiber parts being formed by removing the coating of the plurality of optical fibers and comprises a case made of material having a coefficient of thermal expansion equivalent to optical fibers and having space for enclosing the optical fiber coupler, and fiber supporting portions, being arranged inside of the space of the case and being fused with the bare fiber parts.

Abstract: The protective cladding for a mono-mode directional coupler made of at least two incoming and outgoing fiber optic waveguides which are fused to one another along a coupling segment comprises at least two open cladding parts which can be connected to form a tube-shaped cladding. The material of the cladding parts has the same coefficient of expansion as the waveguide material of the mono-mode directional coupler. The protective cladding, being mechanically tightly connected with the incoming and outgoing fiber optic waveguides while leaving open the coupling segment of the mono-mode directional coupler, is closed off in a gas-tight manner such that in the case of temperature changes, there are no mechanical tensions in the coupling segment.

Abstract: A rigid, low expansion formable housing composition can be used to package optical waveguide couplers. The housing is in intimate contact with and strongly bonded to the coupler being packaged. The housing composition includes a formable polymeric resin, a glass-ceramic or ceramic or glass filler, and, optionally, strengthening fibers. The filler has a low thermal expansion to compensate for the high expansion of the resin. A moisture barrier layer may be placed around the housing composition, and it is possible to incorporate a shock absorbing material between the housing and the moisture barrier layer.

Abstract: An optical component mounting substrate which comprises grooves for holding optical fibers, other grooves for optical components being inserted and optical waveguides is produced with a press molding process. A mold having convex and/or concave surface profiles which are corresponding to the grooves and the optical waveguides to be formed on a surface of the optical component mounting substrate is used as a die in the press molding process. The surface profiles of the mold are precisely transferred onto the surface of a transparent glass base substrate, thereby forming the optical component mounting substrate having a desired surface configuration including the grooves and the optical waveguides. Optical fibers are aligned along the grooves and fixed by a light-curing adhesive.

Abstract: A wide wavelength range-coupler whose light-branching ratio shows low wavelength-dependency, which is provided with a well-shaped light-coupling portion and excellent optical properties and which can easily be connected to other optical fibers as well as a method for the production thereof are herein provided. The light-coupling portion 3 of the optical fiber coupler is formed by fusing and orientating a plurality of single mode optical fibers 1 and 2 partially arranged parallel to one another and these optical fibers 1 and 2 have cores 1a and 2a which are different from one another in diameter, but are substantially identical in the outer diameter of the clad and in the mode field diameter. Each single mode optical fiber as a material for the coupler has a core diameter and a mode field diameter which are correlated through a quadratic function and therefore, there can be selected two optical fibers 1 and 2 which are identical to one another in the mode field diameter, but differ in the core diameter.

Abstract: In a fixing portion of an optical fiber-type wave-divider-multiplexer, an optical fiber glass portion is fixed to a fixing member by an adhesive. A groove reaching at least a core portion of the optical fiber is cut from the fixing member. This groove may be cut up to a position where the optical fiber is cut across. An optical filter is inserted into the cut groove, and is fixed by an adhesive or the like. As a result, the optical fiber can be provided with light passing characteristics corresponding to the characteristics of the optical filter.

Abstract: An optical waveguide device has a casing, a base member housed in the casing, at least one input optical fiber cable and at least one output optical fiber cable which are introduced into the casing, an optical waveguide substrate mounted on the base member and connected to respective ends of the input and output optical fiber cables for transmitting a light signal from the input optical fiber cable to the output optical fiber cable, support bases and holders fixed to the base member for holding end portions of the input and output optical fiber cables on the base member, and a bushing or bushings in the casing for introducing the input and output optical fiber cables into the casing. The optical waveguide substrate has an optical waveguide branched into a plurality of waveguide paths, and input and output optical fiber cables are coupled to each other through the optical waveguide.

Abstract: A fiber optic coupler comprising a plurality of single-mode optical fibers, each of which is tapered to form a small diameter section that extends in contiguous relationship with the small diameter sections of the other fibers to form a coupling region. Each of the fibers has a core surrounded by a cladding of refractive index lower than that of the core. At least one of the fibers has a refractive index pedestal of refractive index n.sub.i between said core and cladding, wherein n.sub.1 >n.sub.i >n.sub.2, n.sub.1 and n.sub.2 being the refractive indices of the core and cladding, respectively.

Abstract: In one aspect, the invention concerns fused fiber optic couplers of the type formed from fibers of transparent substance each having a circular cross-section of preselected diameter. The fibers include a central fiber and at least one ring of closely packed surrounding fibers with at least some of the fibers being optical fibers that have a core and a surrounding cladding. The coupler is formed by the processes of providing the fibers, assembling them in a close-packed relationship, and heating and drawing the assembly of fibers in the close-packed region.We have discovered that the steps involved in forming such a coupler, introduce slight size variations that can seriously affect the performance of the coupler, and that these slight variations can be accommodated by slight, controlled, under-sizing of one or more of the surrounding fibers or over-sizing of the central fiber.

Abstract: In an optical fiber coupler comprising a plurality of optical fibers bundled together and a light-coupling portion which is formed by partially fusing and drawing these bundled fibers and which permits branching of light rays incident upon one of these fibers into the other fibers at a predetermined branching ratio, the optical fiber coupler has a difference between the branching ratio thereof determined immediately after the fusing and drawing operation and that determined after accommodating the coupler in a protective case and then adhering it to the case, equal to or less than 5%. Such an optical fiber coupler can be produced by bundling a plurality of optical fibers 1 and 2, fusing and drawing a part of the bundled optical fibers with heating, fixing the relative positions of these optical fibers 1 and 2 immediately after the fusing and drawing operation and then accommodating in and fixing to a protective case.

Abstract: A fiber optic coupler includes at least two optical fibers having a coupled region and at least one lead portion extending therefrom. The optical fibers have a protective jacket thereon. The protective jacket is removed from the coupled region and from a region of the at least one lead portion adjacent the coupled region resulting in a jacketless coupled region, at least one jacketless lead portion and at least one jacketed lead portion. The fiber optic coupler further includes a protective body having a receiving space therein for receiving the coupled region. The protective body has at least one entrance from which said jacketed lead portion emerges. A rejacket material at least partially surrounds a length of the jacketless lead portion adjacent the jacketed lead portion resulting in a rejacketed lead portion.

Abstract: A transverse load sensitive optical treadle switch. The switch includes a deformable longitudinal housing and a fiber optic assembly positioned within the housing The fiber optic assembly includes an optical fiber having a first end and a second end, the optical fiber being subject to bending upon application of a transverse load to said housing. Means for mounting the optical fiber in the housing so as to permit bending of the fiber in response to application of a transverse load to said housing are provided, the degree of bending sufficient to cause a significant decrease in passage of light through said fiber when said fiber is bent. Means permitting introduction of light into said optical fiber at the first end of the optical fiber and means for permitting the exit of light from the second end are also provided.

Abstract: An achromatic fiber optic coupler of the type wherein a plurality of single-mode optical fibers, each having a core and a cladding, are fused together along a portion of the lengths thereof to form a coupling region. The propagation constants of the fibers are preferably equal; however if the fiber claddings have different refractive indices, the lowest cladding refractive index is n.sub.2. A matrix glass body of refractive index n.sub.3 surrounds the coupling region, n.sub.3 being lower than n.sub.2 by such an amount that the value of .DELTA..sub.2-3 is less than 0.125%, wherein .DELTA..sub.2-3 equals (n.sub.2.sup.2- n.sub.3.sup.2)2n.sub.2.sup.2.