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Showing papers on "Photonic-crystal fiber published in 1987"


Proceedings Article
James P. Gordon1
26 Apr 1987
TL;DR: Optical solitons, pulses with hyperbolic secant shapes and with the correct product of amplitude and width, can propagate without dispersing over long distances near the 1.5μm loss minimum in optical fibers as mentioned in this paper.
Abstract: Optical solitons, pulses with hyperbolic secant shapes and with the correct product of amplitude and width, can propagate without dispersing over long distances near the 1.5-μm loss minimum in optical fibers. It is, therefore, very tempting to think of them as potential candidates for communications purposes. On the one hand, solitons are quite stable and can be maintained by coherent amplification; thus the pulses never need to be reformed. On the other hand, the soliton’s propagation velocity depends on its mean frequency because of fiber dispersion; thus perturbations which cause frequency shifts are very important.

96 citations


Journal ArticleDOI
TL;DR: A novel all-fiber resonant optical cavity which uses two-Fiber reflectors, each formed by a single loop of fiber between the output ports of a fiber directional coupler, which lasing occurs at a wavelength of 1064 nm.
Abstract: We demonstrate a novel all-fiber resonant optical cavity which uses two-fiber reflectors, each formed by a single loop of fiber between the output ports of a fiber directional coupler. The reflectivities of the fiber mirrors are each determined by the coupling ratio and the insertion loss of the fused couplers. When the cavity is formed in this way using a continuous length of Nd(3+)-doped fiber and pumped using a GaAs laser diode, lasing occurs at a wavelength of 1064 nm. Both theoretical and practical descriptions of the device are given.

54 citations


Patent
13 Jan 1987
TL;DR: In this article, an all-fiber mode selector consisting of a single-mode optical fiber (100) and a double-mode optic fiber (110), each having a facing surface (144, 154) formed on one side of the cladding.
Abstract: An all-fiber mode selector comprises a single-mode optical fiber (100) and a double-mode optical fiber (110), each having a facing surface (144, 154) formed on one side of the cladding. The facing surfaces (144, 154) are juxtaposed in close facing relationship. The fibers are selected so that an optical signal propagating in the LP11 propagation mode of the double-mode optical fiber (110) propagates at substantially the same phase velocity as an optical signal propagating in the LP01 propagation mode of the single-mode optical fiber (100). The evanescent fields of the two fibers interact to couple optical energy from the LP" mode of the double-mode optical fiber (110) to the LPOI mode of the single-mode optical fiber (100) and vice versa.

51 citations


Journal ArticleDOI
TL;DR: In this paper, the fabrication of IR optical fibers for the 2-to 14-µm region is described, and cylindrical and square fibers fabricated from rods and tubes are discussed.
Abstract: The fabrication of IR optical fibers for the 2- to 14-µm region is described. Both cylindrical and square fibers fabricated from rods and tubes are discussed. The physical properties of the GeSbSe glasses and optical fibers are reviewed. Fabrication of different fiber bundles is also reported. The applications of IR optical fibers and bundles are described, and system performance and parametric analyses are developed for some applications, including thermal imaging, IR sensors, CO2 laser power guide, and low-loss optical fibers.

45 citations


Patent
05 May 1987
TL;DR: In this article, a water penetration detection system using an optical fiber sensor and a water-absorbent material disposed along the optical fiber in contiguous relation to the fiber is presented.
Abstract: A water penetration-detecting apparatus includes an optical fiber sensor having an optical fiber, and a water-absorbent material disposed along the optical fiber in contiguous relation to the fiber. The water-absorbent material, when absorbing water, expands volumetrically so as to apply a pressure to an outer peripheral surface of the optical fiber to bend the fiber. A detecting means is connected to the optical fiber sensor for detecting a bending of the optical fiber.

42 citations


Journal ArticleDOI
TL;DR: In this paper, the design of in-line acoustooptic modulators for single-mode fibers is discussed, which consists of a cylindrically symmetric piezoelectric transducer fabricated on the fiber surface.
Abstract: The design of in-line acoustooptic modulators for single-mode fibers is discussed. The basic configuration consists of a cylindrically symmetric piezoelectric transducer fabricated on the fiber surface, so that the fiber itself acts as a cylindrical acoustic resonator. Depending on the fiber design, the acoustic wave can induce phase, birefringence, or polarization modulation of the light in the fiber. Pairs of the polarization modulators in series can be used to shift the optical frequency. Factors affecting the performance of all of these devices are discussed.

41 citations


Patent
01 Sep 1987
TL;DR: In this article, a planar surface is formed on the planar cladding surfaces of the optical fibers to remove undesired linear polarization components from optical signals guided by the fibers while permitting a desired linear polarization component to propagate unattenuated.
Abstract: A fiber gyroscope provides improved bias stability and repeatability and has a greatly reduced polarizer extinction ratio requirement compared previous devices. This fabrication technique is compatible with both an all fiber gyroscope configuration and an integrated optics or bulk optics device. The present invention comprises a substrate that is preferably formed of fused silica. A pair of optical fibers, or two lengths of one fiber, are mounted to the substrate, and first planar surfaces are formed in the cladding. Optical couplers, polarizers and other components used in forming the rotation sensor are formed on the planar cladding surfaces of the fibers. Polarizers formed on the fibers have a transmission axis aligned with an axis of birefringence of the fiber to remove undesired linear polarization components from optical signals guided by the fibers while permitting a desired linear polarization component to propagate unattenuated. A sensing coil of optical fiber is arranged to guide light between the first and second optical fibers, the first and second optical fibers and the optical coupler cooperating to introduce counterpropagating light waves in the sensing coil.

40 citations


Patent
14 Aug 1987
TL;DR: In this paper, the structure of an optical fiber can be accurately determined by irradiating the side wall of the optical fiber with a light such as a white light, a monochromatic light or the like in the direction perpendicular to the axis of optical fiber.
Abstract: A method of and apparatus for examining the structure of an optical fiber such as eccentricity, clad and core diameters, and nonroundness of clad. The structure of the optical fiber can be accurately determined by irradiating the side wall of the optical fiber with a light such as a white light, a monochromatic light or the like in the direction perpendicular to the axis of the optical fiber, detecting an image of the light transmitted through the optical fiber and/or diffraction fringes formed by lights diffracted by the outer edge of the optical fiber to obtain a luminance distribution of the light traversing the optical fiber, and calculating the luminance distribution to thereby obtain accurate structural parameters of the optical fiber.

39 citations


Journal ArticleDOI
TL;DR: Self-induced stochastic behavior for the evolution of light along a periodically perturbed two-mode nonlinear optical waveguide is predicted and implications for recently demonstrated all-optical switching using birefringent fibers are discussed.
Abstract: Self-induced stochastic behavior for the evolution of light along a periodically perturbed two-mode nonlinear optical waveguide is predicted. Implications for recently demonstrated all-optical switching using birefringent fibers are discussed.

37 citations


Patent
16 Jun 1987
TL;DR: In this article, an optical fiber device comprises a core and a cladding, the core being made of an optical material having a refractive index n₁, and the cladding being made by an anisotropic optical material with a similar index.
Abstract: An optical fiber device (31) comprises a core (35) and a cladding (33), the core (35) being made of an optical mate­ rial having a refractive index n₁, and the cladding being made of an optical material having a refractive index n₂, end (34) of the optical fiber from which light radiates form­ ing a plane that is inclined to the fiber axis by an angle ϑ, a light reflective layer being formed at least on the outer pe­ riphery of said radiating end, and the two refractive indices n₁ and n₂ satisfying the following relation (1): n₁-n₂≧ 0.01 (1).

37 citations


Patent
27 Nov 1987
TL;DR: In this article, a waveguide having a prescribed refractive index in tight contact with the clad part of an optical fiber for wave guiding is presented. But the waveguide is fixed by a layer 51 of an adhesive agent and a photodetector 30 is provided to the end of the wave guide.
Abstract: PURPOSE:To efficiently take out signal light to the outside by disposing a waveguide having a prescribed refractive index in tight contact with the clad part of an optical fiber for wave guiding. CONSTITUTION:The waveguide 5 has the refractive index above the refractive index of the clad part of the optical fiber 10 for guiding the in-circuit signal light. This waveguide 5 is disposed in such a manner that the waveguide comes into contact with the clad part by an much as a prescribed length in the same direction as the signal light guiding direction of the optical fiber 20. The waveguide is fixed by a layer 51 of an adhesive agent and a photodetector 30 is provided to the end of the waveguide 5. The radiation mode and clad mode light generated in the optical fiber juncture of this constitution are partly guided through the waveguide 5 to the outside so that the signal light is partly taken out. The conversion efficiency of about -20dB is obtd. according to this method. The excitation of the external signal light of the same level as the level of the in-circuit signal light is possible if a high-output light source is used.

Journal ArticleDOI
TL;DR: A Mg-ion in-diffusion process was applied to form an optical guiding structure in LiNbO(3) single-crystal fibers, yielding quasi-single-mode (two modes) propagation.
Abstract: A Mg-ion in-diffusion process was applied to form an optical guiding structure in LiNbO3 single-crystal fibers. A parabolic refractive-index profile was formed in a 56-μm-diameter, c-axis MgO:LiNbO3 fiber, yielding quasi-single-mode (two modes) propagation.

Proceedings ArticleDOI
14 Oct 1987
TL;DR: In this paper, an intensity bio-chemical fiber optic sensor (BCFOS) where absorption of t he evanescent wave by a dye-labeled solution is used to modulate, attenuate, and attenuate the intensity of the signal in the core of the fiber is described.
Abstract: Fiber Optic intensity sensors based on the interaction between an external medium and t he evanescent wave of unclad and tapered multimode and single mode fibers have been developed to measure refractive index, temperature and liquid level. Here we describe an intensity bio-chemical fiber optic sensor (BCFOS) where absorption of t he evanescent wave by a dye-labeled solution is used to modulate, attenuate, t he intensity of t he signal in t he core of the fiber. The fabrication and performance is described for laboratory prototype sensors using etched multimode and tapered single mode fibers.

Patent
05 Oct 1987
TL;DR: In this paper, a single-mode optical fiber consisting of a core and cladding of non-circular cross section and having different refractive indices forming a single mode guiding region was used for de-coupling of waves polarized along the axis of the fiber.
Abstract: A laser-optical fiber interface including the combination of a solid state laser producing a point source of polarized light and a polarization-holding, single-mode optical fiber. The optical fiber comprising a core and cladding of non-circular cross section and having different refractive indices forming a single mode guiding region which permits the de-coupling of waves polarized along the axis of the fiber. The outer surface of the fiber includes an indexing surface with a predetermined geometric relationship to the guiding region. The optical fiber being mounted upon a substrate for receiving and supporting the indexing surface of the fiber with the solid state laser so that the end of the fiber is placed and aligned adjacent the solid state laser.

Patent
16 Apr 1987
TL;DR: In this paper, the authors proposed an optical fiber sensor with a sensitive zone which cooperates with a retroreflecting surface through the agency of an optical couplant, which returns into the optical fiber all light losses which escape from the fiber in the sensitive zone.
Abstract: In an optical fiber sensor, the fiber has a sensitive zone which cooperates with a retroreflecting surface through the agency of an optical couplant. The function of the retroreflecting surface is to return into the optical fiber all light losses which escape from the fiber in the sensitive zone.

Patent
27 Jul 1987
TL;DR: In this article, a modal domain optical fiber sensor for vibration monitoring and as a mechanical motion detector is presented, where a laser that focuses coherent light through a lens into one end of a multimode optical fiber is secured to a mechanical mechanism for exciting vibrations.
Abstract: A modal domain optical fiber sensor for vibration monitoring and as a mechanical motion detector. A laser that focuses coherent light through a lens into one end of a multimode optical fiber. The fiber is secured to a mechanical mechanism for exciting vibrations. The other end of the optical fiber passes its output through a spatial filter and into a photodetector. A variable voltage signal from the photodetector is fed to a monitoring unit, such as an oscilloscope or a microcomputer, for analysis. Of particular significance is the intentional mismatch between the wavelength of the light 18 from the laser and the single mode cut-off wavelength of the glass optical fiber. In a preferred embodiment, the optical fiber has a wavelength of 850 nm and the coherent light has a wavelength of 633 mm.

Journal ArticleDOI
TL;DR: In this paper, a singlemode optical fiber connection to high-silica ridged waveguide formed on a silicon substrate is described using a guiding groove fabricated at the waveguide end.
Abstract: Single-mode optical fiber connection to high-silica ridged waveguide formed on a silicon substrate is experimentally described. Fiber alignment and fixing processes are easily accomplished using a guiding groove fabricated at the waveguide end. An average connection loss of 0.4 dB was achieved. Optimum groove configuration, temperature stability of fiber connection, and polarization maintaining characteristics are discussed with experimental results.

Proceedings ArticleDOI
14 Oct 1987
TL;DR: In this paper, a fiber optic pressure sensor using elasto-optic birefringence in a single-mode fiber was presented. But the results were limited to a pressure range of 0 to 1000 bars.
Abstract: Experiments are performed toward the development of a fiber optic pressure sensor which uses the elasto-optic birefringence in a single-mode fiber The 'side-hole' fiber-structure may be viewed as a PANDA-structure with open channels instead of the stress generating rods in its cross-section The use of the side-hole fiber exploits the high reproducibility of silica serving as the elastic reference By the side-hole geometry external hydrostatic pressure is converted into an anisotropic stress in the core region Additionally, a stress concentration by a factor of 3 to 5 can be achieved by suitable choice of the geometry of the channels In the experimental setup, the fiber is exposed in a pressure chamber directly to the pressure to be measured The chamber is designed for a pressure range of 0 to 1000 barsThe induced birefringence is determined by passing a polarized laser beam through the fiber and by bi-directional counting the periods of phase delay between the two polarization-eigenstates of the fiber at the output Thus, the sensor operates in an incremental mode Using a fiber length of 10 cm, a pressure induced birefringence of 778 rad/(bar-m) was measured at a wavelength of 1300 nm The resolution of optical phase evaluation is ni2, corresponding to a pressure resolution of approx 2 bars The overall accuracy of the sensor is better than ± 05% in the pressure range of 100-1000 bars where unambiguous phase evaluation was possible Below 100 bars, in one fiber problems were caused near the point where the the birefringence vanishes The experimental sensor-head is connected to the evaluation unit by a polarization-maintaining single-mode fiber, supplying the laser light, and three electrical leads for the detector signals A version without any electrical lead to the sensor head is planned, in which the light source and the signal detectors are connected by optical fibers

Journal ArticleDOI
TL;DR: In this article, a course of lectures given by Dr Cheo to first year graduates from the aerospace, electronics and telecommunications industries is described as an attempt to gather in one place the fundamentals of the various component fields of fibre optics, namely guided wave optics, semiconductor light sources and detectors and digital communications.
Abstract: This book emerged from a course of lectures given by Dr Cheo to first year graduates from the aerospace, electronics and telecommunications industries. It is an attempt to gather in one place the fundamentals of the various component fields of fibre optics, namely guided wave optics, semiconductor light sources and detectors and digital communications. As might be expected from its origins, the book assumes graduate level knowledge of electromagnetic solid state and quantum mechanical theory, though a short review is given of basic electromagnetism. Strangely enough, Dr Cheo also states that it is his intention to provide general readers with an easy-to-read text that wil l acquaint them with the subject. In actual fact there is very little in the book that does not require a graduate level science or mathematics background.

Journal ArticleDOI
S. Nagel1

Patent
08 Sep 1987
TL;DR: In this article, a method for determining the refractive index profile of an optical fiber is presented. But the method is not suitable for the case where light from an intense optical source is focused at the bare fiber end portion of the test fiber.
Abstract: A method is disclosed for determining the refractive index profile of an optical fiber (12) wherein light from an intense optical source (16) is focused at the bare fiber end portion of the test fiber. A small amount of light will be coupled into the optical fiber where for the short length of uncoated fiber only cladding modes are excited. The index of refraction is determined directly by analy­zing the intensity distribution emitted from the optical fiber (12) with a lens system (24) having a limited numerical aperture (26).

Proceedings ArticleDOI
01 Jan 1987
TL;DR: In this article, an index-matched microlens is fabricated on the tip of a single-mode fiber and the lens is formed by etching the fiber until only a "whisker" of pure core material remains.
Abstract: In this paper we describe a new fiber lensing technique in which an index-matched microlens is fabricated on the tip of a single-mode fiber The lens is formed by etching the fiber until only a "whisker" of pure core material remains This whisker then is cut and arc melted back to form a lens of proper radius for optimal laser-to-single-mode fiber coupling High average coupling efficiencies of greater than 45% (best value 61%) have been measured and will be reported The ability to etch many fibers at the same time with reproducible results indicates that the technique is compatible with batch processing We will explain the lens formation technique in detail and describe the conditions necessary to obtain optical coupling efficiencies Finally, the coupling sensitivity to lateral misalignment between laser and fiber will be presented© (1987) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only

Proceedings ArticleDOI
28 Apr 1987
TL;DR: In this paper, a simple fiber optic chemical sensor is presented which may be used to detect in situ and in real time concentrations of gases and liquids, which operates on the principle of evanescent field and differential spectroscopy.
Abstract: A simple fiber optic chemical sensor is reported which may be used to detect in situ and in real time concentrations of gases and liquids. The sensor, comprised of a single LED source and a cladding-free multimode fiber, operates on the principle of evanescent field and differential spectroscopy. Exhibiting a linear response to relative humidity, this sensor selectively detects water vapor while remaining insensitive to source power fluctuations.


Proceedings ArticleDOI
10 Jul 1987
TL;DR: In this article, the curves of coupling efficiency versus the longitudinal and transverse misalignments show that these kinds of connection can be useful in medium or high power laser application, and they have been tested with large diameter core optical fibers in different filling conditions.
Abstract: Bulb-ended fiber to flat-ended fiber connections and bulb-ended fiber to bulb-ended fiber connections have been tested with large diameter core optical fibers in different filling conditions and different arrangements.The curves of coupling efficiency versus the longitudinal and transverse misalignments show that these kinds of connection can be useful in medium or high power laser application.

Proceedings ArticleDOI
01 Apr 1987
TL;DR: In this paper, a pulsed Er:Yag laser was used to determine the damage threshold of fluoride glass fibers, which was then used for laser power transmission through fluoride glass fiber.
Abstract: Laser power transmission through fluoride glass fibers is possible, but requires stringent glass processing techniques to avoid laser induced damage. A pulsed Er:Yag laser was used to determine the damage threshold of these fibers.

Patent
23 Mar 1987
TL;DR: In this paper, a method for detecting incomplete coverage of hermetic coatings applied to opti fibers during in-line optical fiber fabrication procedures as well as off-line applications is presented.
Abstract: A method detects incomplete coverage of hermetic coatings applied to opti fibers during in-line optical fiber fabrication procedures as well as off-line applications. A fluorescent material surrounds the core region of the optical fiber prior to the formation of the hermetic coating on the optical fiber and energy is radiated in the optical fiber to propagate in the cladding mode. This causes an excitation of the fluorescent material to fluoresce in response to the propagated energy. An appropriately disposed detector detects levels of emitted fluorescence along the length of the optical fiber to indicate where the hermetic coating is incomplete or where pinholes in the hermetic coating are located. Optionally, the fluorescent material is located outside of the cladding layer, inside of the cladding layer near its outer surface or throughout the cladding region to fluoresce when excited by the propagated energy. Different wavelengths of radiation can be used which excite different fluorescent materials so that pinholes or incomplete coating coverage can be detected in hermetic coatings that have different chemical compositions.


Journal ArticleDOI
TL;DR: Optical fibers are becoming increasingly important in the areas of data communication and sensing as advantage is taken of their low attenuations, which result in little signal loss over long distances of fiber.
Abstract: Optical fibers are becoming increasingly important in the areas of data communication and sensing as advantage is taken of their low attenuations, which result in little signal loss over long distances of fiber. However, the fiber attenuations are wavelength dependent, and there are spectral regions where the fibers have lower attenuations as well as areas where the light losses are very severe. In order for one to select the best regions for transmission, the fiber must be well characterized spectroscopically.

Journal ArticleDOI
TL;DR: In this article, a birefringence induced by the optical Kerr effect in single-mode glass fiber waveguides was investigated, and a study was made of the dependences of the process of inducing the bireringence on the natural birerringence, on the orientation of the polarization of the radiation, and on the pump radiation power.
Abstract: A birefringence induced by the optical Kerr effect in single-mode glass fiber waveguides was investigated. A study was made of the dependences of the process of inducing the birefringence on the natural birefringence, on the orientation of the polarization of the radiation, and on the pump radiation power. Oscillations of the intensity of a probe wave were observed under certain conditions of excitation of these fiber waveguides with pump radiation.