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Showing papers on "Photonic-crystal fiber published in 1992"


Journal ArticleDOI
TL;DR: In this article, the authors describe a near-field optical technique that enables the development of submicron-sized optical fiber sensors, which have demonstrated their spatial resolving abilities in measuring the pH of buffer solutions inside micron-size holes in a polycarbonate membrane.
Abstract: Optical fiber sensors have several advantages over electrical-based sensors in many applications in chemistry and biology, but not with respect to minaturization and response time. Here the authors describe a near-field optical technique that enables the development of submicron-sized optical fiber sensors. The technology is based on nanofabricated optical fiber tips and near-field photoinitiated polymerization. Multimode or single-mode optical fibers are drawn into submicron optical fiber tips and then coated with aluminum to form submicron optical fiber light sources. Submicron pH sensors, as an example for small sensors, have been prepared by incorporating fluoresceinamine into an acrylamide-methylenebis(acrylamide) copolymer that is attached covalently to a silanized fiber tip surface by photoinitiated polymerization. The sensors have demonstrated their spatial resolving abilities in measuring the pH of buffer solutions inside micron-size holes in a polycarbonate membrane. These submicron pH sensors have millisecond response times due to their extremely small sizes. 20 refs., 6 figs.

156 citations


Journal ArticleDOI
TL;DR: In this paper, a new crucible drawing method was developed for the drawing of fibers with glass cladding, and the extrinsic losses caused by some oxide impurities were suppressed by the purification of raw elements.
Abstract: Sulfide, selenide and telluride glass fibers were prepared for infrared optical applications. A new crucible drawing method was developed for the drawing of fibers with glass cladding. The extrinsic losses caused by some oxide impurities were suppressed by the purification of raw elements. The transmission loss and mechanical strength, i.e., bending and tensile, of each fiber were investigated before and after the heat treatment under humid conditions. The fibers obtained were used for the power delivery of CO2 laser (10.6 μm) and CO laser (5.4 μm). The antireflection coating onto fiber ends and cooling of fiber with gas or water were examined for the improvement of power transmission efficiency. A fiber cable having ZnSe lens at the output end was prepared for medical and other applications. Temperature monitoring, thermal imaging and gas sensing were also tried using the fibers.

143 citations


Patent
09 Sep 1992
TL;DR: In this paper, a system for coupling laser radiation at a high power to an optical fiber while dissipating heat from scattered laser and optical pump radiation was proposed, including a protective ferrule surrounding a portion of the optical fiber.
Abstract: A system for coupling laser radiation at a high power to an optical fiber while dissipating heat from scattered laser and optical pump radiation, including an optical fiber, a protective ferrule surrounding a portion of the optical fiber extending from the input face of the optical fiber and welded to the fiber in the region of the input face and otherwise separated from the fiber by an air space, and a holder surrounding the ferrule to absorb scattered radiation and dissipate heat.

98 citations


Patent
04 Sep 1992
TL;DR: In this article, the photopolymerization has been applied as a means to photo-chemically attach an optically active material (60) to the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture.
Abstract: This invention relates generally to the development of and a method of fabricating a fiber optic micro-light source and sensor (50). An optical fiber micro-light source (50) is presented whose aperture is extremely small yet able to act as an intense light source. Light sources of this type have wide ranging applications, including use as micro-sensors (22) in NSOM. Micro-sensor light sources have excellent detection limits as well as photo stability, reversibility, and millisecond response times. Furthermore, a method for manufacturing a micro optical fiber light source is provided. It involves the photo-chemical attachment of an optically active material onto the end surface of an optical fiber cable which has been pulled to form an end with an extremely narrow aperture. More specifically, photopolymerization has been applied as a means to photo-chemically attach an optically active material (60). This process allows significant control of the size of the micro light source (50). Furthermore, photo-chemically attaching an optically active material (60) enables the implementation of the micro-light source in a variety of sensor applications.

91 citations


Journal ArticleDOI
X. P. Mao1, R. W. Tkach1, Andrew R. Chraplyvy1, Robert M. Jopson1, R.M. Derosier1 
TL;DR: In this article, the effects of fiber uniformity on stimulated Brillouin scattering thresholds have been measured and extended to the case of non-uniform fibers, which enables the design of long fiber spans with ten times higher stimulated-branching thresholds.
Abstract: The effects of fiber uniformity on stimulated Brillouin scattering thresholds have been measured, and the theory for stimulated Brillouin scattering in uniform fibers has been extended to the case of nonuniform fibers. This theory enables the, design of long fiber spans with ten times higher stimulated Brillouin scattering thresholds. >

87 citations


Patent
28 Feb 1992
TL;DR: An asymmetric hyperbolic microlens on the end of a single-mode optical fiber enhances the fiber's coupling to elliptical laser beams as mentioned in this paper, which is useful to pump erbium-doped fiber amplifiers.
Abstract: An asymmetric hyperbolic microlens on the end of a single-mode optical fiber enhances the fiber's coupling to elliptical laser beams The lenses, with controlled eccentricity ratios, are made by micromachining the end of the fiber with a pulsed CO₂ laser as the fiber is directed, preferably by computer control, about the focused laser beam Coupling efficiencies of 90 percent (-075 dB) have been realized with single transverse mode lasers at a wavelength of 098 µm having an approximately 3 to 1 beam ellipticity With multimode lasers at 148 µm having similar elliptical beams, the asymmetric lenses demonstrate an almost 2 dB increase in coupling efficiency over symmetric hyperbolic microlenses Such lasers are useful to pump erbium-doped fiber amplifiers About 120 mw was coupled from such a laser into single-mode fiber

82 citations


Patent
27 Jul 1992
TL;DR: In this article, an in-fiber Bragg grating is used to flatten the gain slope of a fiber optical amplifier or optical fiber laser by diverting excess spontaneous emission therefrom.
Abstract: An in-fiber Bragg grating is used to flatten the gain slope of a fiber optical amplifier or optical fiber laser. The grating can be formed using photorefractive techniques, and is placed within a guided wave portion of a doped optical fiber. The grating is oriented at a nonperpendicular angle with respect to a longitudinal axis of the fiber, and has an interaction wavelength that is selected to flatten the gain slope of the device by diverting excess spontaneous emission therefrom. The interaction wavelength is preferably selected to correspond to a wavelength at or near that at which the spontaneous emission produced by the fiber peaks.

79 citations


Journal ArticleDOI
TL;DR: A sapphire optical fiber intrinsic Fabry–Perot interferometric sensor is demonstrated that has been demonstrated for temperature measurement and has a resolution of 0.2°C.
Abstract: A sapphire optical fiber intrinsic Fabry–Perot interferometric sensor is demonstrated. A length of multimode sapphire fiber that functions as a Fabry–Perot cavity is spliced to a silica single-mode fiber. The interferometric signals of this sensor are produced by the interference between the reflection from the silica–sapphire fiber splice and the reflection from the free end face of the sapphire fiber. This sensor has been demonstrated for temperature measurement. A resolution of 0.2°C has been obtained over a measurement range of 310°C to 976°C.

77 citations


Journal ArticleDOI
TL;DR: In this article, a theoretical model for the calculation of the output power of an erbium-doped fiber ring laser was introduced that is based on a previously derived gain equation for Erbium doped fiber amplifiers.
Abstract: The output power of an erbium-doped fiber ring laser has been measured as a function of pump power, emission wavelength, doped-fiber length, and reflectivity of the output coupler. A theoretical model for the calculation of the output power is introduced that is based on a previously derived gain equation for erbium-doped fiber amplifiers. The calculated values are in good agreement with the experimental data, confirming the applicability of the theory to a reliable modeling of the output power of erbium fiber ring lasers. >

66 citations


Patent
25 Sep 1992
TL;DR: In this paper, a cladding composition comprising a fluorine-containing methacrylic monomer or a mixture of such monomers, and methyl methacrylate is polymerized and then extruded or solution coated onto an optical fiber core.
Abstract: A cladding composition comprising a fluorine-containing methacrylic monomer or a mixture of such monomers, and methyl methacrylate, such that the cladding composition is polymerized and then extruded or solution coated onto an optical fiber core, and an optical fiber comprising a core coated with such cladding composition, having a lower refractive index than the optical fiber core.

50 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of tapering on the sensing region of the optical fibers was investigated for remote evanescent wave detection with optical fibers, where the majority of the fiber remains cladded while only a small portion of the core is exposed to perform the analysis.
Abstract: Optical biosensors are analytical tools employed in environmental, biotechnology and clinical fields. For remote evanescent wave detection with optical fibers, the majority of the fiber remains cladded while only a small portion of the core is exposed to perform the analysis. To improve the sensitivity of this type of fiber optic biosensor, tapering the sensing region of the fiber was investigated. Silica fibers were tapered into two geometries: step and continuous tapers. To determine the effect of tapering on detection levels, a fluoroimmunoassay was performed on fibers with nontapered, step-tapered and continuously tapered geometries. Solutions containing a fluorescent analyte were circulated over an antibody-coated fiber and the fluoresence signal measured The minimum detection limit for fibers with 10 cm sensing region was 1.56 nM, 0.31 nM and 0.16 nM for nontapered, step-tapered and continuously tapered fibers, respectively. Continuous tapering of the sensing region of an optical fiber offe...

Patent
02 Sep 1992
TL;DR: In this paper, a broadband optical fiber coupler comprising at least three continuous optical fibers fused at a region of coupling, at least one of the continuous optical fiber being dissimilar to others of the optical fibers in the region of couplings, the region being of length and the dissimilarity being of a degree to provide broadband response over a predetermined range of wavelengths.
Abstract: A broadband optical fiber coupler comprising at least three continuous optical fibers fused at a region of coupling, at least one of the continuous optical fibers being dissimilar to others of the continuous optical fibers in the region of coupling, the region of coupling being of a length and the dissimilarity being of a degree to provide broadband response over a predetermined range of wavelengths. A related method for making a broadband optical fiber coupler is also disclosed.

PatentDOI
TL;DR: In this paper, a planar and linear fiber optic sensor system comprised of a sensor element and a reference element is presented. But the sensor and reference fibers are shaped circularly and uniformly, heat treated or bonded together and embedded in a spiral pattern within a low Bulk Modulus and Young's Modulus elastomer encapsulant.
Abstract: A interferometric planar and linear fiber optic sensor system comprised of a sensor element and a reference element. In the planar fiber optic sensor system the sensor and reference fibers are shaped in loops circularly and uniformly, heat treated or bonded together and embedded in a spiral pattern within a low Bulk Modulus and Young's Modulus elastomer encapsulant. The invention results in high and frequency independent sensitivity which minimizes acceleration effects. For the linear sensor, the sensing fiber is shaped in loops forming a linear chain which is embedded in an appropriate low bulk modulus elastomeric encapsulant. The reference fiber is shaped in loops around a cylindrical aluminum mandrel within which the input and output fiber cables and couplers are encapsulated in a high bulk modulus material epoxy resin. In both the planar and linear forms, the sensing and reference fiber may be of equal length, however, the reference fiber may be of a shorter length when a coherent light source is utilized.

Journal ArticleDOI
TL;DR: In this paper, a model based on birefringence dispersion is proposed for a Fabry-Perot Nd-doped fiber laser, where wide wavelength tunability is achieved either by rotating the polarizer or by varying, with an in-line polarization controller.
Abstract: When an intracavity polarizer is introduced into a Fabry-Perot Nd-doped fiber laser, wide wavelength tunability is achieved either by rotating the polarizer or by varying, the fiber birefringence with an in-line polarization controller. The intracavity polariser also produces considerable line-narrowing. A model based on birefringence dispersion is proposed. >

Patent
31 Aug 1992
TL;DR: An optical interferometer comprises a multi-mode sapphire fiber as a high temperature sensor which produces reference and sensor reflections that produce optical fringes at the output of a detector coupled to the silica optical fiber via an opto-coupler.
Abstract: An optical interferometer comprises a multi-mode sapphire fiber as a high temperature sensor. One end of the sapphire fiber is coupled to a silica fiber and, in turn, to the sapphire fiber. The sapphire fiber sensor produces reference and sensor reflections that produce optical fringes at the output of a detector coupled to the silica optical fiber via an opto-coupler. The optical fringes are related to displacements of the sensor which, in turn, can provide an indirect measurement of pressure, strain or temperature of the surface.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that it is possible to fabricate efficient microlenses directly on the ends of polarization-maintaining fiber, which are able to couple more than 70% of the light from a laser diode into the fiber, are made by micromachining an aspheric surface over the core region of the fiber with a CO/sub 2/ laser.
Abstract: The authors demonstrate that it is possible to fabricate efficient microlenses directly on the ends of polarization-maintaining fiber. The lenses, which are able to couple more than 70% of the light from a laser diode into the fiber, are made by micromachining an aspheric surface over the core region of the fiber with a CO/sub 2/ laser, as the fiber spins and is directed by computer about the beam. >

Patent
Ryozo Yamauchi1, Akira Wada1, Tetsuo Nozawa1, Daiichirou Tanaka1, Tetsuya Sakai1 
08 Jun 1992
TL;DR: In this article, an optical fiber consisting of a core and a cladding layer with at least one of the constitutional parameters changing along the longitudinal direction of the optical fiber is presented.
Abstract: The present invention is directed to an optical fiber comprising a core and a cladding layer wherein at least one of the constitutional parameters thereof changes along the longitudinal direction of the optical fiber. In order to present a useful optical fiber wherein the occurrence of a Brillouin scattering is prevented, an optical fiber having altered constitutional parameters is found to be effective. The constitutional parameters mean the parameters which determine the constitution of the optical fiber and is capable of influencing the condition of electromagnetic wave transmitting therethrough such as light or acoustic wave. The constitutional parameters include diameter of the core, index of refraction of the core, diameter of the optical fiber, composition of the glass, residual stress of the core. Some examples are disclosed about their manufacturing process and the test results. Much improvement was measured, especially in the use for a single mode optical fiber.

Patent
Jean-Marc Delavaux1
07 Feb 1992
TL;DR: In this article, a hybrid pumping scheme for rare-earth doped fiber amplifiers is described, in which at least two pump sources, operating at different wavelengths, coupled to a section of doped optical fiber, such as erbium-doped optical fibre.
Abstract: A hybrid pumping scheme for rare-earth doped fiber amplifiers is disclosed. In particular, the arrangement utilizes at least two pump sources, operating at different wavelengths, coupled to a section of doped optical fiber, such as erbium-doped optical fiber. Optical multiplexers, such as fused fiber couplers, may be used to couple the message signal desired to be amplified, as well as the pump sources, to the doped fiber section. For certain embodiments, the doped fiber may be segmented into separate components, with the length of each component determined with respect to the wavelength of the associated pump signal.

Patent
07 Aug 1992
TL;DR: Optical fibers are embedded in metal structures and components by using a pair of stress-relieving tubes at the air-metal interface of the optical fiber as discussed by the authors, which is a common technique for optical fiber deployment.
Abstract: Optical fibers are embedded in metal structures and components by using a pair of stress-relieving tubes at the air-metal interface of the optical fiber.

Patent
Yasuhisa Tanisawa1, Tetsuji Ueda1
11 May 1992
TL;DR: In this article, the first optical fiber is a TEC (thermal expand core) fiber having an end portion whose core diameter is larger than that of the other portion of the fiber.
Abstract: An optical module comprises a capillary in which first and second optical fibers are connected The first optical fiber is aligned through a lens to an optical device, and the second optical fiber functions as a pigtail cord connected to an external optical fiber The first optical fiber is a TEC (thermal expand core) fiber having an end portion whose core diameter is larger than that of the other portion thereof, and the first optical fiber is a normal optical fiber which has a uniform core diameter smaller than the core diameter of the TEC fiber

Patent
31 Dec 1992
TL;DR: In this paper, achromatic fiber optic coupler of the type wherein three singlemode optical fibers are fused together along a portion of the lengths thereof to form a coupling region is described.
Abstract: An achromatic fiber optic coupler of the type wherein three single-mode optical fibers are fused together along a portion of the lengths thereof to form a coupling region. Each fiber includes a core and a cladding, the lowest refractive index of the fiber claddings being n2. The fibers are disposed in a triangular array in the coupling region. A matrix glass body of refractive index n3 surrounds the coupling region, n3 being lower than n2 by such an amount that the value of Δ2-3 is less than 0.125%, wherein Δ2-3 equals (n2 2' -n3 2)/2n2 2.

Journal ArticleDOI
TL;DR: A fiber-optic refractive-index sensor that is applicable to a long-distance measurement based on the variation of the output intensity that is induced by radiation loss at the bend, which enables us to measure the refractive index of the outer medium.
Abstract: We report a fiber-optic refractive-index sensor that is applicable to a long-distance measurement. The sensor consists of a silica glass fiber bent into a U shape with a bending radius of typically several hundred micrometers. The cladding at the tip of the sensor is stripped off. The sensing mechanism is based on the variation of the output intensity that is induced by radiation loss at the bend, which enables us to measure the refractive index of the outer medium. A fabrication method of fusing the sensor with a CO2 laser and etching with HF is described. Multipoint measurements of optical-time-domain reflectometry are also described.

Patent
26 Oct 1992
TL;DR: In this paper, a hollow fiber with, over the full length of the fiber and between each fiber channel (3, 4) and the core, at least one stress zone (5, 6) to create an anisotropic stress distribution which subjects the fiber core to a tensile stress.
Abstract: The invention is a hollow fiber with, over the full length of the fiber and between each fiber channel (3, 4) and the core, at least one stress zone (5, 6) to create an anisotropic stress distribution which subjects the fiber core to a tensile stress. The cable design is advantageous in that it is possible to control the sign of the fiber intrinsic birefringence. The cable is thus advantageous for use as a pressure sensor or pressure transducer.

Patent
28 Aug 1992
TL;DR: A variable attenuator for a fiber optic transmission system includes first and second optical fibers which are axially aligned as mentioned in this paper, and the fibers are provided with spherical polishes, and the radius of each of the fibers originates at an axis which is offset from an axis of the fiber cores.
Abstract: A variable attenuator for a fiber optic transmission system includes first and second optical fibers which are axially aligned. The fibers are provided with spherical polishes. The radius of each of the fibers originates at an axis which is offset from an axis of the fiber cores.

Journal ArticleDOI
TL;DR: A mathematical model is presented that predicts birefringence changes in an optical fiber as the cladding is removed and it is shown that this model approximates a highly elliptical fiber core with a rectangular dielectric waveguide.
Abstract: A mathematical model is presented that predicts birefringence changes in an optical fiber as the cladding is removed. This model approximates a highly elliptical fiber core with a rectangular dielectric waveguide. The birefringence calculations obtained with the model compare well with experimental evidence obtained with real-time birefringence monitoring during cladding removal by chemical etching. The information is used to control the amount of cladding removed from a D fiber to within ~ 0.05 μm for use in the production of passive optical fiber components.

Patent
15 Sep 1992
TL;DR: In this paper, a method of limiting coupling losses between a monomode optical fiber and an optical system having a mode diameter W'o that is different from Wo is presented, which is characterized by the fact that a piece (4) of multimode fiber is welded onto the end of said monOMode fiber, the weld creating an adiabatic cone in the region where the cores meet.
Abstract: The present invention relates to a method of limiting coupling losses between a monomode optical fiber (2) having a mode diameter of Wo, and an optical system (1) having a mode diameter W'o that is different from Wo, said method being characterized by the fact that a piece (4) of multimode fiber is welded onto the end of said monomode fiber, said piece of multimode fiber having a length in the range 0.1 mm to 5 mm, and having the same cladding outside diameter as said monomode fiber, a mode diameter substantially equal to W'o, and an index difference δn lying in the range 5×10-3 to 50×10-3, the weld creating an adiabatic cone in the region where the cores meet.

Patent
06 Nov 1992
TL;DR: In this paper, a hybrid fiber optic sensor is created by inserting the lead-in and lead-out optical fibers into a small tube such that a gap is provided between the fibers, and two interfacial reflections that interfere with one another, thus providing a method of measuring changes in gap length in the same was as a typical Fabry-Perot type interferometer.
Abstract: A device and method are described for measuring changes association with a gap between a lead-in optical fiber and a lead-out optical fiber. A hybrid fiber optic sensor is created by inserting the lead-in and lead-out optical fibers into a small tube such that a gap is provided between the fibers. Laser pulses incident on the gap create two interfacial reflections that interfere with one another, thus providing a method of measuring changes in gap length in the same was as a typical Fabry-Perot type interferometer. Moreover, a reflection from the far end of the lead-out fiber gives gap information in the same way as typical intensity-based sensor. Together the two measurements overcome the limitations that occur when each technique is used separately, and are made possible by means of the above hybrid fiber optic sensor which contains both a Fabry-Perot interferometer portion and an intensity-based sensor portion.

Patent
03 Aug 1992
TL;DR: A controllable waveguide display based on a cladding (3), supercladding (1 and 6) and/or core (4) utilizing liquid crystals is described in this article.
Abstract: A controllable waveguide display based on a cladding (3), supercladding (1 and 6) and/or core (4) utilizing liquid crystals is described. An electric field applied through a fiber causes the liquid crystal layer to become aligned. Changes in the refractive index of the liquid crystal layer causes light to switch out of the fiber. In one embodiment light is coupled into a supercladding (6) running alongside the core and reflected out of the fiber at a reflector pit (35) cut in the fiber. Parallel arrays of fibers are used to cover a substrate and make large viewing screens. A tapered supercladding (6) helps improve the contrast ratio of screens using fiber taps. A thin cladding (3) and closely spaced dark cladding (2) also help improve the screen contrast ratio. Color techniques based on a three core fiber that shares a single supercladding (1) is introduced. An illumination method is also taught which breaks white light into colored components (73) with dielectrc filters (103) to efficiently utilize white light (102). An electronic feedback system (96) is introduced which provides screen brightness and color uniformity under varying temperature and environmental conditions.

Journal ArticleDOI
TL;DR: In this paper, a self-aligned put-in microconnector is proposed to provide alignment-free coupling of optical components and single-mode fibers in a planar microlens substrate.
Abstract: A novel optical fiber coupling scheme, i.e. put-in self-aligning, is proposed. This is composed of put-in microconnectors made by a self-aligned process and provides alignment-free coupling of optical components and single mode fibers. The authors have fabricated a put-in microconnector consisting of an etched fiber jack and an optical plug formed on the rear surface of a planar microlens substrate. >

Journal ArticleDOI
TL;DR: The high efficiency of this prototype fiber supports the idea that this confinement technique should yield intensity gains of many orders of magnitude as the optimal fiber design is achieved.
Abstract: A 1.6-m-long, flexible, hollow glass fiber with a gradually diminishing bore diameter has been used efficiently to compress the size of an x-ray beam as it reflects from the inside walls of the fiber by total external reflection. The transmission characteristics of the fiber are reported for monochromatic synchrotron radiation of 8.04, 13, and 20 keV, as well as for CuKα radiation from a conventional x-ray tube. Intensity enhancements as large as 10 that correspond to a transmission efficiency of 54% were observed. The high efficiency of this prototype fiber supports the idea that this confinement technique should yield intensity gains of many orders of magnitude as the optimal fiber design is achieved.