Abstract: A laser guide optical fiber (100) used for transmitting a laser beam includes an optical fiber body (110) including a core (111) and a clad (112), and a quartz chip (120) integrally provided at an end surface on the light entering side of the optical fiber body (110) and including an optical waveguide portion, where at least the optical waveguide portion of the quartz chip (120) is made of pure quartz. The quartz chip (120) includes a light entering surface subjected to surface fusion treatment.

Abstract: A method of forming a light guide, web structures and light guide structures are described herein. The method includes cutting a web to provide film pieces, where a first major surface of each film piece is capable of emitting light when light is injected into the film piece from a first cut edge of the film piece. The step of cutting produces structures on the first edge of the film.

Abstract: An optical transmission apparatus includes a light receiving element and an optical waveguide. The light receiving element receives light. The optical waveguide includes a core, a clad and a concave portion. The clad is adjacent to the core. The concave portion is formed in a portion of the core or a portion of the clad and diffuses the light. The portion of the core or the portion of the clad emits the light toward the light receiving element.

Abstract: A light transmission module includes a reinforcement component for reinforcing a substrate. The reinforcement component is arranged on a surface mounted with the optical element of the substrate. The reinforcement component includes at least two structural portions longer than a maximum length portion of the optical element when seen from a direction perpendicular to the substrate surface. The two structural portions are arranged facing each other with a region, where at least the optical element is arranged, in between when seen from the direction perpendicular to the substrate surface.

Abstract: A method positions a first end of an optic fiber a distance from a target and applies a laser light to a second end of the optic fiber such that the laser light is guided by the optic fiber from the second end to the first end of the optic fiber and is emitted from the first end of the optic fiber toward the target as a beam of light. The beam of light has a first area of incidence at the target. The optic fiber is then bent such that the beam of light continues to reach the target and such that the area of incidence of the beam of light at the target changes without changing the distance between the first end of the optic fiber and the target. A device having two plates with raised portions inside a metal case is provided for bending the optic fiber.

Abstract: Provided is a near field light generator to be utilized, effectively generating near field light with respect to a recording medium. Thus, disclosed is a near field light generator possessing a waveguide comprising a core and a cladding brought into contact with the core, to guide light having an electric field component perpendicular to an interface between the core and the cladding, and a metallic structure body provided on an outputting end face onto which light of the waveguide is output, to generate near field light by receiving light guided by the waveguide, wherein the metallic structure body is placed straddling the core and the cladding on the outputting end face in such a way that the metallic structure body receives the electric field component protruding from the interface to the cladding.

Abstract: An aspect of the present disclosure may include an apparatus having an optical waveguide. The optical waveguide may have a distal end surface non-normal to a longitudinal centerline of a distal end portion of the optical waveguide, wherein the distal end surface may define a portion of an interface configured to redirect electromagnetic radiation propagated from within the optical waveguide and incident on the portion of the interface to a direction offset from the longitudinal centerline. The apparatus may further include a capillary component which may have a first portion of an inner surface heat-fused to a portion of an outer surface of the optical waveguide.

Abstract: A mirror embedded optical waveguide according to the present invention comprises: a core; an angled cut face in the core; an adhesive layer on the angled cut face, the adhesive layer having approximately the same refractive index as that of the core; and a metal film on the adhesive layer, the metal film being formed by transfer.

Abstract: Embodiments of the invention are directed to an optical device, such as an optical device for use in a laser system. One embodiment of the optical device includes first and second components. A fluorocarbon polymer layer is between the first and second components. Embodiments of the fluorocarbon polymer layer comprise a fluorocarbon polymer in the form of an adhesive, an oil, a lubricant or a paste. In one embodiment, the fluorocarbon polymer layer is in the form of an adhesive that bonds the first and second components together.

Abstract: A method of making a planar lightwave circuit (PLC) waveguide capable of being integrated with a surface-mounted component is presented. The method entails etching a silicon substrate to form a slanted wall, forming a nonreflective waveguide portion on the silicon substrate, and depositing a reflective layer on the slanted wall. Light travels through the nonreflective waveguide portion in substantially a first direction, and the light from the nonreflective waveguide portion strikes the reflective layer to be redirected in a second direction. The second direction may be the direction toward the surface-mounted component. A PLC waveguide device made with the above method is also presented.

Abstract: Excess optical power in a waveguide device is appropriately terminated. According to one embodiment of the present invention, the waveguide device comprises a termination structure filled with a light blocking material for terminating light from the end section of a waveguide. This termination structure can be formed by forming a groove on an optical waveguide by removing the clad and core, and filling the inside of that groove with a material attenuating the intensity of the light (light blocking material). In this manner, light that enters into the termination structure is attenuated by the light blocking material, and influence on other optical devices as a crosstalk component can be suppressed. With such termination structure, not only the influence on optical devices integrated on the same substrate, but also the influence on other optical devices directly connected to that substrate can be suppressed.

Abstract: In an embodiment of the invention, an optical connector for optically coupling respective end faces of two optical fiber cables including an optical fiber composed of a core and a cladding includes a beat shrinkable tube, a cable insertion tube disposed in the heat shrinkable tube for inserting thereinto and butting the respective end faces of the two optical fiber cables, an uncured refractive index matching resin disposed between the beat shrinkable tube and the cable insertion tube, and a resin supply hole formed in the cable insertion tube for supplying the uncured refractive index matching resin to an inside of the cable insertion tube.

Abstract: The present invention provides a process for producing an optical connector, an apparatus for producing the same, and a process for forming a polymer coating film on an end face of a fibrous dielectric, which can dispose a refractive index adjuster only onto an end face of an optical transmitting medium with excellent reproducibility. Such a process includes bringing an end surface of the optical transmitting medium close to an end face of a liquid refractive index adjuster, while charging at least one of the optical transmitting medium and the liquid refractive index adjuster, thereby adhering the liquid refractive index adjuster to the end face of the optical transmitting medium, and thereafter solidifying the adhered liquid refractive index adjuster to obtain the refractive index adjuster.

Abstract: Presented herein are methods, systems, devices, and computer-readable media for dual-tube stereoscopes. Embodiments may include an elongated body comprising a proximal end and a distal end, the proximal end having at least one proximal opening, the distal end having first and second distal openings; a first waveguide coupled to the first distal opening; and a second waveguide coupled to the second distal opening. There may also be optics situated near the proximal end of the elongated body and configured to receive light from the first and second waveguides and to transmit the received light through the at least one proximal opening onto a single light-receiving device. Some embodiments include processing a single received digital image, comprising two sub-images, to produce two images viewable stereoscopically, for example.

Abstract: An optical selector switch contains an optical waveguide that includes a first optical waveguide portion having a first light-transmissivity, a second optical waveguide portion having a second light-transmissivity, reflecting members that reflect light, and a light-dividing device that reflects and transmits light; at least one light-emitting unit that emits the light toward the first optical waveguide portion of the optical waveguide; and at least one light-receiving unit that receives the light which is incident to the first optical waveguide portion of the optical waveguide from the light-emitting unit, based on a directivity due to an angle of the incident light to the first optical waveguide portion of the optical waveguide, wherein the incident light to the first optical waveguide portion is emitted radially toward the circumference of the second optical waveguide portion of the optical waveguide.

Abstract: Disclosed herein is a light receiving apparatus, including: a light receiving section including a light receiving element; a transparent part; and a light guiding part inserted in the groove; the groove having, on the front face side, a side face formed as an arcuately curved face convex toward the front face side and having the same shape in any cross section perpendicular to the front face and also to the depthwise direction of the groove; the light guiding part having a side face opposing to the side face of the groove on the front face side and formed as an arcuately curved face which is convex toward the front face side in a state wherein the light guiding part is inserted in the groove and which has the same shape in any cross section perpendicular to the front face and also to the depthwise direction of the groove.

Abstract: The present invention provides an optical device and an exposure apparatus capable of suppressing a reduction in light output. The optical device of the present invention includes a laser light source which emits laser light having a short wavelength (e.g., 160 to 500 nm), a lens, a transparent member and an optical fiber provided with a junction-inhibiting film. The optical device is configured such that light density of abutment faces between the transparent member and the optical fiber formed with the junction-inhibiting film is 4464 W/mm2 or less, thereby suppressing a reduction in light output which may be caused by fusion.

Abstract: The present invention comprises: a laser light source 101 operable to output a laser light; an optical component 114 operable to couple, to an optical fiber 126, the laser light outputted from the laser light source 101; an actuator 118 operable to hold the optical component 114; a photoreceiver 503 operable to monitor the laser light outputted from the optical fiber; and a control device 117 operable to drive the actuator 118 in accordance with a result of the monitoring by the photoreceiver 503, thereby controlling a position of the optical component 114.

Abstract: An optical coupling structure that interfaces between optical devices mounted on a substrate and optical waveguides formed in the substrate. A manufacturing method includes preparing a wafer formed on an inorganic solid material on a dicing tape and cutting the back surface of the wafer to form substantially angled portions using a dicing blade having a point angle. The dicing tape is stripped from the wafer and the wafer is separated at the valleys between the substantially angled portions to obtain an optical coupling element. The obtained optical coupling element is a three-dimensional polyhedral light-reflecting member having a mirror surface corresponding to a surface of the wafer. The obtained optical coupling element is inserted into a trench that opens, substantially perpendicular to an optical waveguide of an optical transmission substrate, in the main surface of the optical transmission substrate to provide a structure for optical coupling with the outside.

Abstract: An acoustic sensor includes at least one photonic crystal structure having at least one optical resonance with a resonance frequency and a resonance lineshape. The acoustic sensor further includes a housing mechanically coupled to the at least one photonic crystal structure. At least one of the resonance frequency and the resonance lineshape is responsive to acoustic waves incident upon the housing.

Abstract: A tunable optical filter is formed by the longitudinal alignment of two opposing end sections of single-mode optical fibers. On at least one of the end sections is a collimator fiber section which is formed from a section of a graded-index, multimode optical fiber which is an odd number of quarter pitches long. The collimator fiber section has an angled end surface which joined to the reciprocally angled end surface of the at least one single-mode optical fiber end section. Piezoelectric material controls the separation between the first and second single-mode optical fiber end sections and sets the wavelengths of optical signals carried through the first and second single-mode optical fiber end sections.

Abstract: A fiber laser device includes a laser pump for irradiating a laser beam, an optical component, an optical fiber and an optical sensor. The optical component has a first and a second output end, wherein a portion of the laser beam is output from the first output end and another portion of the laser beam is output from the second output end. The optical fiber including a core and a cladding layer is optically coupled between the laser pump and the optical component. A inclined angle ? of the first output end satisfies the following relations that ?NA/2????NA, and ?NA=sin?1(NA·ncladding/ncore), where NA is numerical aperture of optical fiber, ncore is refractive index of the core, and ncladding is refractive index of the cladding layer. The optical sensor is disposed at a light-transmission path of the laser beam reflected by the first output end.

Abstract: A laser transmission system is used for inspecting workpieces. The system has a source of laser beams that is coupled to a first lens assembly. A first hollow core waveguide is operably coupled to the first lens assembly. An end of an optical fiber coupled to the first hollow core waveguide. A second hollow core waveguide is coupled to the other end of the optical fiber. A second lens assembly operably coupled to the second hollow core waveguide. The length of the hollow core waveguides range from about 5 to 100 times the focal lengths of the lens assemblies. A motion control system is operably coupled to the second hollow core waveguide and the second lens assembly for controllably displacing the second hollow core waveguide and the second lens assembly with respect to a workpiece.

Abstract: An adapter couples a length of optical fiber to a hollow probe and to an optical coherence tomography instrument. The length of optical fiber may be greater than the length of the adapter itself. The optical fiber is fixed to an optical coupler at a proximal end of the adapter and may be maintained in a curved configuration by features located in an internal cavity of the adapter. An optical fiber advance mechanism be used to advance and/or retract the length of optical fiber to align it within the hollow probe.

Abstract: A laser guide optical fiber (100) used for transmitting a laser beam includes an optical fiber body (110) including a core (111) and a clad (112), and a quartz chip (120) integrally provided at an end surface on the light entering side of the optical fiber body (110) and including an optical waveguide portion, where at least the optical waveguide portion of the quartz chip (120) is made of pure quartz. The quartz chip (120) includes a light entering surface subjected to surface fusion treatment.

Abstract: Disclosed are radiation systems and methods, including a system that includes a waveguide to direct radiation from a first radiation source, a covering to cover at least part of the waveguide and one or more optical fibers embedded in the covering to direct radiation from a second radiation source. Also disclosed is system that includes a hollow waveguide assembly including a proximal portion and a distal portion that can be coupled to the proximal portion at a coupling area, the hollow waveguide assembly being configured to direct radiation from a first radiation source to an output port at a distal end of the distal portion of the hollow waveguide assembly, and a coupling unit to couple into the distal portion of the hollow waveguide assembly radiation from a second radiation source and the radiation from the first source delivered through the proximal portion.

Abstract: Apparatus, systems and methods for use in analyzing discrete reactions at ultra high multiplex with reduced optical noise, and increased system flexibility. Apparatus include substrates having integrated optical components that increase multiplex capability by one or more of increasing density of reaction regions, improving transmission of light to or collection of light from discrete reactions regions. Integrated optical components include reflective optical elements which re-direct illumination light and light emitted from the discrete regions to more efficiently collect emitted light. Particularly preferred applications include single molecule reaction analysis, such as polymerase mediated template dependent nucleic acid synthesis and sequence determination.

Abstract: An optical structure on an optical fiber and a method of fabrication is provided. The optical structure includes an end of an optical fiber and a layer formed on the end of the optical fiber. The layer comprises one or more first portions having a first optical pathlength in a direction perpendicular to the layer and one or more second portions having a second optical pathlength in the direction perpendicular to the layer, the second optical pathlength different from the first optical pathlength.

Abstract: The present invention relates to a method for amplifying the detected signal in a gas sensor. More specifically, the present invention relates to a method for increasing the concentration of the gas which is being detected in a sample or increasing the concentration of a gas which is directly obtained from the gas in the sample by chemical reaction. The gas which is to be detected is nitric oxide (NO). In particular, the method concerns the selective conversion of NO to NO2 which allows a threefold amplification of the number of analyte molecules in NO trace gas analysis in a single amplification cycle. Subsequent reduction or thermal decomposition of the obtained NO2 can provide NO again, which can again be introduced in a new amplification cycle. Multiple (n) amplification cycles can provide a sensitivity amplification by a factor 3n. The method can be combined with a multitude of detection methods and tolerates a high humidity.

Abstract: An optical cable module has an optical waveguide formed by surrounding a core with a clad layer and a light-receiving/emitting element, installed on a supporting substrate. A light-releasing face of the optical waveguide or a light-incident face to the optical waveguide is aligned so as to face a light-receiving face or a light-emitting face of the light-receiving/emitting element. The optical waveguide is formed into a film shape having flexibility, and provided with a reinforcing member that prevents a deflection from occurring in the optical waveguide. The optical waveguide is placed on a protruding portion from a supporting face of the optical waveguide on the supporting substrate.

Abstract: An optical device includes: a first optical member having a light-exit end at which light exits the first optical member; a second optical member having a light-entrance end which abuts the light-exit end through a protective medium and from which the light enters the second optical member; and the protective medium which is arranged between the light-exit end and the light-entrance end, and suppresses fixing together of the light-exit end and the light-entrance end. Specifically, the protective medium is transparent and arranged between the light-exit end and the light-entrance end, and is reusable even after the light-exit end and the light-entrance end are pressed together with a pressure of approximately 0.5 or 1 kgf and are then separated from each other.

Abstract: A method and an apparatus according to an embodiment of the invention includes a capillary for use in side-firing optical fibers. An outer surface of the capillary defines a recessed transmissive portion of the capillary. The area of the recessed transmissive portion can be a four-sided area or an area with a rounded boundary, for example. An optical-fiber-core end portion disposed within the capillary can include an end surface configured to redirect laser energy in a lateral direction and through the recessed transmissive portion of the capillary. The lateral direction can be substantially normal to the recessed transmissive portion of the capillary and offset from a longitudinal axis of the distal end portion of the core. The end surface of the core can be non-perpendicular to the longitudinal axis. In some embodiments, a multilayer dielectric coating can be disposed on the end surface of the core.

Abstract: The subject invention pertains to a method and apparatus for multiplexing in optical fiber communications. The subject invention relates to a method and apparatus for spatial domain modulation in optical wavelengths. In a specific embodiment, the subject invention relates to a spatial domain multiplexer (SDM) for use with an optical fiber. Preferably, the input channels coupled into the fiber optic cable include collimated laser beams. The techniques of the subject invention can be utilized with single mode and multi mode waveguide structures, for example, single mode and multi mode optical fibers. The subject invention is applicable to step index optical fiber and to graded index optical fiber. Applications of the subject technology can include secure data links, for example, which can modulate data such that if the data is intercepted, the data cannot be interpreted. The subject methods and apparatus can also be used in conjunction with other multiplexing techniques such as time-domain multiplexing.

Abstract: An optical intermediary component is suitable for guiding a light from an output optical path into an input optical path. The optical intermediary component includes a light guiding portion extending along a light axis. The light guiding portion has a light incident surface and a light emitting surface at two opposite ends thereof respectively. The light from the output optical path passes through the light incident surface and the light emitting surface of the light guiding portion in sequence, and is guided into the input optical path. The area of the light incident surface is greater than that of the light emitting surface. Therefore, a high assembly tolerance may reduce the manufacturing and assembly cost.

Abstract: A microsphere-based analytic chemistry system and method for making the same is disclosed in which microspheres or particles carrying bioactive agents may be combined randomly or in ordered fashion and dispersed on a substrate to form an array while maintaining the ability to identify the location of bioactive agents and particles within the array using an optically interrogatable, optical signature encoding scheme. A wide variety of modified substrates may be employed which provide either discrete or non-discrete sites for accommodating the microspheres in either random or patterned distributions. The substrates may be constructed from a variety of materials to form either two-dimensional or three-dimensional configurations. In a preferred embodiment, a modified fiber optic bundle or array is employed as a substrate to produce a high density array. The disclosed system and method have utility for detecting target analytes and screening large libraries of bioactive agents.

Abstract: A method and an apparatus according to an embodiment includes a distal end portion of an optical fiber disposed inside a lumen defined along a curved path within a capillary. The distal end surface of the optical fiber can be substantially flush with a portion of an outside surface of the capillary that defines a transmissive portion. The distal end portion of the optical fiber and the curved path can be collectively configured to direct laser energy through the transmissive portion in a lateral or side-fired direction that is offset from a longitudinal axis or centerline of the capillary. In some embodiments, more than one optical fiber can be disposed along the curved path. In other embodiments, more than one curved path can be defined within the capillary such that a distal end portion of an optical fiber can be disposed along each of the curved paths.

Abstract: The invention relates to a near-field antenna comprising a dielectric shaped body having a tip. The shaped body is characterized in that at least the surface of the tip is metallized, thereby enhancing the sensitivity of devices comprising the near-field antenna, for example, spectroscopes, microscopes or read-write heads.

Abstract: An optical fiber part includes an optical fiber having a main fiber, a taper fiber and a small-diameter fiber. The core diameter of the taper fiber decreases along an optical axis. Further, a heat-radiation silicon adhesive that is a highly heat-conductive material having heat conductivity of 4 W/m·K or higher has been applied to the entire area of the outer circumference of the taper fiber and a part of the small-diameter fiber next to the taper fiber. An input end of the optical fiber is connected to a semiconductor laser having an output power of 10 W. Light output from the laser propagates through the optical fiber and output from the output end. A part of light that has propagated through the main fiber and entered the taper fiber is output through the cladding thereof. Heat generated by light output from the cladding is transferred through the heat-radiation silicon adhesive and radiated.

Abstract: Substrate-guided relays that employ light guiding substrates to relay images from sources to viewers in optical display systems. The substrate-guided relays are comprised of an input coupler, an intermediate substrate, and an output coupler. In some embodiments, the output coupler is formed in a separate substrate that is coupled to the intermediate substrate. The output coupler may be placed in front of or behind the intermediate substrate, and may employ two or more partially reflective surfaces to couple light from the coupler. In some embodiments, the input coupler is coupled to the intermediate substrate in a manner that the optical axis of the input coupler intersects the optical axis of the intermediate substrate at a non-perpendicular angle.

Abstract: Methods and structures for reducing and/or eliminating moisture penetration in an optical package. The optical package may include (1) a layer of inorganic material placed over the points of the optical package susceptible moisture penetration of the optical package; (2) a portion of hygroscopic material placed over the points of the optical package susceptible to moisture penetration; (3) a layer of hygroscopic material placed on the interior surface of the optical package; and/or (4) a layer of hydrophobic material coated on the optical surfaces of the optical package.

Abstract: Aspects of the invention can provide an illumination device capable of preventing or reducing a reduction in efficiency of utilization of lights emitted from the light source, and also suitable to display high-quality moving images, and a display device and a projection type display device using this illumination device.

Abstract: An object of the present invention is to provide an optical transmission structural body capable of preferably transmitting an optical signal between an optical wiring and an optical waveguide irrespective of a shape of a portion of the optical wiring, the portion being connected to a core part of the optical waveguide. The optical transmission structural body of the present invention is constituted so that at least an optical wiring and an optical waveguide are connected to each other and an optical signal can be transmitted between a core of the optical wiring and a core part of the optical waveguide, wherein a portion of the optical wiring, the portion being connected to the core part of the optical waveguide, is not specially subjected to a planarization processing or has a surface roughness Ra based on JIS B 0601 of 0.1 ?m or more.

Abstract: A short-pulse measurement and detection apparatus utilizing an aperiodic non-linear quasi-phase matched (A-QPM) material. The bandwidth of the A-QPM non-linear material is such that an interaction between a first signal and a second signal occurs, facilitating measurements of signal properties by techniques such as intensity auto-correlation, intensity cross-correlation, and pulse sampling.

Abstract: A luminometer is provided comprising a flow through waveguide and one or more detectors. The flow through waveguide has at least two openings and the sample is free to enter from one opening and exit from the other. The flow through waveguide can be made of material that guides emission light to a bottom end of the flow through waveguide. One or more detectors may be provided which detect the emission light coming out of the bottom of the flow through waveguide. A fluorometer/photometer is also provided that comprises a flow through waveguide, one or more excitation light sources, and one or more optical detectors. The flow through waveguide has a hollow region to hold the sample. The excitation light is introduced at an angle or perpendicular to one surface of the flow through waveguide. The flow through waveguide is made of material that can guide absorption and/or emission light to the bottom end of the flow through waveguide.

Abstract: A light-illuminating probe with increased spatial spread of an external illumination light and a fundus observing apparatus, a fundus surgery apparatus, and an endoscope using the light-illuminating probe are provided. The light-illuminating probe includes a light-transmitting portion which is constructed with at least a first dielectric material having a light transparency and a light-radiating portion which is constructed with a second dielectric material having a light transparency to be formed in an extension portion of the light-transmitting portion.

Abstract: An optical device has a waveguide structure comprising a thin strip (12) having finite width and thickness of material having a relatively high free charge carrier density supported by a membrane (14) having a predetermined thickness of material that has a relatively low free charge carrier density. The dimensions of the width and thickness of the strip and the thickness of the supporting membrane are such that, when the waveguide structure is surrounded at least partially by an environment (E) having a low free charge carrier density, optical radiation having a wavelength in a predetermined range couples to the waveguide structure and propagates along the length thereof as a plasmon-polariton wave that permeates at least part of the environment (E).

Abstract: An optical module can achieve an optical system using a transmission-type diffraction grating for bending the optical path of incident light with a specific wavelength by about 90°. A substrate of the transmission-type diffraction grating is mounted at an angle in a range of ±5° with respect to the design incident angle ? of the incident light. The optical system can be applied to a light multiplexing/demultiplexing module.

Abstract: An apparatus and method for reducing speckle of a laser beam is disclosed. The apparatus includes a light guide, a highly reflective mirror at the input face of the light guide and a partially-transmissive display after the exit face of the light guide. A coherent laser beam is introduced into the light guide through a clear aperture in the highly reflective mirror. Within the light guide, the laser beam gets separated into plural, successive beamlets having different phase shifts, different polarization states and/or path length differences equal to or greater than the coherence length of the laser beam. The beamlets exit through the partially-transmissive display to provide output laser light with reduced speckle. The light guide can be either a solid light pipe of transmissive material or a hollow tunnel with reflective interior sidewalls.

Abstract: An acoustic sensor includes at least one photonic crystal structure having at least one optical resonance with a resonance frequency and a resonance lineshape. The acoustic sensor further includes a housing substantially surrounding the at least one photonic crystal structure and mechanically coupled to the at least one photonic crystal structure. At least one of the resonance frequency and the resonance lineshape is responsive to acoustic waves incident upon the housing.

Abstract: An apparatus for transmitting laser light and redirecting the light laterally relative to an axis of the apparatus includes an optical fiber having both a core and a cladding surrounding the core. The optical fiber terminates at a distal tip having a surface inclined relative to the axis of the optical fiber. A tubular member surrounds the optical fiber at its distal end. The distal end of the optical fiber has a portion opposing the tubular member for being united to the tubular member. The distal portion is joined to the tubular member by an intermediate material selected to have an index of refraction matching that of the core and the tubular member.