Showing papers on "Optical fiber published in 1988"
TL;DR: In this article, the theory and application of fiber loop reflectors, fabricated by forming a fiber loop between the output ports of a directional coupler, is described, and the reflectivity of the loop is shown to depend upon the coupling characteristics of the coupler and on the degree of birefringence in the fiber loop.
Abstract: The theory and application of fiber loop reflectors, fabricated by forming a fiber loop between the output ports of a directional coupler, is described. The reflectivity of the loop is shown to depend upon the coupling characteristics of the coupler and on the degree of birefringence in the fiber loop. Measured loop reflectivities, in terms of wavelength response, coupling ratio, and loop birefringence are shown to agree very well with theory. Two applications of the fiber reflector are briefly discussed; an all fiber laser and a duplex optical communications link using a single light source. >
450 citations
Patent•
14 Oct 1988
TL;DR: In this paper, the authors describe a catheter consisting of a single optical fiber or a plurality of optical fibers arranged to give overlapping output patterns for large area coverage, for tissue removal and repair.
Abstract: Laser energy produced by a laser operating in the mid-infrared region (approximately 2 micrometers) is delivered by an optical fiber in a catheter to a surgical site for biological tissue removal and repair. Disclosed laser sources which have an output wavelength in this region include: Holmium-doped Yttrium Aluminum Garnet (Ho:YAG), Holmium-doped Yttrium Lithium Fluoride (Ho:YLF), Erbium-doped YAG, Erbium-doped YLF and Thulium-doped YAG. For tissue removal, the lasers are operated with relatively long pulses at energy levels of approximately 1 joule per pulse. For tissue repair, the lasers are operated in a continuous wave mode at low power. Laser output energy is applied to a silica-based optical fiber which has been specially purified to reduce the hydroxyl-ion concentration to a low level. The catheter may be comprised of a single optical fiber or a plurality of optical fibers arranged to give overlapping output patterns for large area coverage.
405 citations
01 Jan 1988
TL;DR: Optical Fiber-Chemical Sensing using Direct Spectroscopy Chemical Sensing Using Indicator Dyes Dynamic Light Scattering Applied and Its Application in Concentrated Suspensions In Vivo Medical Sensors Fiber-Optic Gyros Fiber Optic Sensors for Condition Monitoring and Engineering Diagnostics Sensors in Industrial Systems Distributed Sensors as discussed by the authors.
Abstract: Optical Fiber-Chemical Sensing Using Direct Spectroscopy Chemical Sensing Using Indicator Dyes Dynamic Light Scattering Applied and Its Application in Concentrated Suspensions In Vivo Medical Sensors Fiber-Optic Gyros Fiber-Optic Sensors for Condition Monitoring and Engineering Diagnostics Sensors in Industrial Systems Distributed Sensors -- Recent Developments Multiplexing Techniques for Fiber-Optic Sensors Fiber Optics and Smart Structures Fiber-Optic Sensors -- Commercial Presence
364 citations
01 Jan 1988
TL;DR: In this article, the theory of planar waveguides is discussed and a detailed discussion of their fabrication and fabrication is presented. But the focus of this paper is on planar guides, and not on all waveguide types.
Abstract: Optical waveguides, also known as “dielectric” waveguides, are the structures that are used to confine and guide the light in the guided-wave devices and circuits of integrated optics. This chapter is devoted to the theory of these waveguides. Other chapters of this book discuss their fabrication by such techniques as sputtering, diffusion, ion implantation or epitaxial growth. A well-known optical waveguide is, of course, the optical fiber which usually has a circular cross-section. In contrast, the guides of interest to integrated optics are usually planar structures such as planar films or strips. Our discussion will focus on these planar guides even though most of the fundamentals are applicable to all optical waveguide types.
335 citations
TL;DR: In this paper, the capability of fiber-optic light guides to transmit a variety of optical signals simultaneously has been exploited to construct an optical fiber sensor for measurement of both oxygen and carbon dioxide.
Abstract: The capability of fiber-optic light guides to transmit a variety of optical signals simultaneously has been exploited to construct an optical fiber sensor for measurement of both oxygen and carbon dioxide. The oxygen-sensitive material (a Kieselgel-adsorbed fluorescent metal-organic complex) and the CO/sub 2/-sensitive material (an immobilized pH indicator in a buffer solution) are entrapped in a gas-permeable polymer matrix that is attached to the distal end of the fiber. Both indicators have the same excitation wavelength (in order to avoid energy transfer) but quite different emission maxima. The two emission bands can easily be separated with the help of interference filters and give independent signals. Oxygen can continuously be determined in the 0-200 Torr (0-26.6 kPa) range with +/- 1 Torr accuracy and CO/sub 2/ in the 0-150 Torr (0-20 kPa) range with +/- 1 Torr. The accuracy is higher at low partial pressure, so that the detection limits are at approx. 0.5 Torr in both cases.
293 citations
TL;DR: All-optical switching of solitons between the two linear modes of a nonlinear coherent coupler made from a dual-core fiber operating in the anomalous dispersion regime is predicted.
Abstract: We predict all-optical switching of solitons between the two linear modes of a nonlinear coherent coupler made from a dual-core fiber operating in the anomalous dispersion regime.
287 citations
TL;DR: The first clear observation of the fundamental dark soliton in optical fibers was made in this article, where the authors used specially shaped, antisymmetric input pulses, which closely correspond to the form of the universal light soliton, and showed that at appropriate power levels the dark pulses propagate without broadening.
Abstract: We present evidence of soliton propagation by 185-fsec dark pulses at a wavelength of 0.62 \ensuremath{\mu}m in a 1.4-m length of single-mode optical fiber. Our experiments utilize specially shaped, antisymmetric input pulses, which closely correspond to the form of the fundamental dark soliton. At appropriate power levels the dark pulses propagate without broadening. Our measurements are in quantitative agreement with numerical solutions to the nonlinear Schr\"odinger equation and constitute the first clear observation of the fundamental dark soliton in optical fibers.
285 citations
TL;DR: In this paper, a force microscope using a fiber-optic interferometer as the cantilever displacement sensor is described, achieving a sensitivity of 1.7×10−4 A/(Hz)1/2 for frequencies above 2 kHz.
Abstract: A force microscope is described which uses a fiber‐optic interferometer as the cantilever displacement sensor. Low thermal drift and reduced susceptibility to laser frequency variation are achieved due to the small (several micrometer) size of the interferometer cavity. A sensitivity of 1.7×10−4 A/(Hz)1/2 is observed for frequencies above 2 kHz. The drift rate of the sensor is on the order of 3 A/min. As an initial demonstration, laser‐written magnetic domains in a thin film sample of TbFeCo were imaged.
285 citations
TL;DR: It is shown that a novel class of optical solitons is possible in nonlinear dispersive media with birefringence.
Abstract: It is shown that a novel class of optical solitons is possible in nonlinear dispersive media with birefringence.
269 citations
TL;DR: Measurements of pulse reshaping by the nonlinear coupler provide compelling evidence of the device's ability to response on a femotosecond time scale.
Abstract: We report all-optical switching of 100-fsec pulses in a fused-quartz dual-core-fiber directional coupler. The length of the device is 0.5 cm, and the switching power is 32 kW. Pulses are routed to either of two separate fiber guides, depending on the input power. Measurements of pulse reshaping by the nonlinear coupler provide compelling evidence of the device's ability to response on a femotosecond time scale.
269 citations
TL;DR: In this paper, a simple opto-electronic device is described for measuring lifetimes of a long-lived fluorophore with a frequency-modulated LED as light source.
16 Dec 1988
TL;DR: In this paper, the authors present an approach for coupling radiation into a single-mode core of an optical fiber laser with a relatively large, multimode cladding at a location which is displaced from the center of the cross-section of the cladding.
Abstract: Apparatus for coupling radiation into a single-mode core of an optical fiber laser has a single-mode core disposed within a relatively large, multimode cladding at a location which is displaced from the center of the cross-section of the cladding. The cladding is surrounded by a further layer to prevent radiation from propagating out of the cladding. In addition, the apparatus preferably has slight bends to enhance the coupling of radiation from the cladding into the single-mode core. A further embodiment has a single-mode fiber laser disposed in a relatively large, multimode, slab cladding which, in turn, is surrounded by another cladding to prevent radiation from propagating out of the large cladding.
Patent•
22 Jun 1988TL;DR: In this article, a crossbar switch with bifurcated optical fibers (200) having equivalent ends connected to transmitters and receivers (261,..., 264) and single ends in a linear array (245) that is adjacent to a linear micro lens array (240) and a linear spatial light modulator (230) is described.
Abstract: A crossbar switch (200) with bifurcated optical fibers (271, . . . , 286) having equivalent ends connected to transmitters (251, . . . , 254) and receivers (261, . . . , 264) and single ends in a linear array (245) that is adjacent to a linear micro lens array (240) and a linear spatial light modulator (230) with light emitted from a single end reflected back into the single end for undeflected pixels in the spatial light modulator (230) and lost for deflected pixels.
TL;DR: In this paper, a method to determine the individual strain-optic coefficients in single-mode fibers is described, based on two photoelastic experiments, namely, the polarimetric measurement of optical activity induced by mechanical twist and the interferometric measurement of optic-path-length change induced by static longitudinal strain.
Abstract: A method to determine the individual strain-optic coefficients in single-mode fibers is described. It is based on two photoelastic experiments, namely, the polarimetric measurement of optical activity induced by mechanical twist and the interferometric measurement of optical-path-length change induced by static longitudinal strain. For fibers with pure silica core and B/sub 2/O/sub 3/ doped cladding, the optical activity per unit twist rate and the phase change per unit fiber elongation have been measured to be 0.1472 and 1.150*10/sup 7/ rad/m, respectively. The strain-optic coefficients have been measured to be p/sub 11/=0.113 and p/sub 12/=0.252, 7% lower than those of bulk silica. >
IBM1
TL;DR: Measurements of the reshaping of 0.3-psec dark pulses due to their passage through 10 m of single-mode optical fiber suggest the formation of dark-pulse solitons, according to the predictions of the nonlinear Schr\"odinger equation.
Abstract: We report measurements of the reshaping of 0.3-psec dark pulses due to their passage through 10 m of single-mode optical fiber. The measurements were performed as a function of intensity and the observed strong reshaping agrees qualitatively with the predictions of the nonlinear Schr\"odinger equation which suggest that we have observed the formation of dark-pulse solitons.
TL;DR: Polarization dispersion in single-mode fiber with random polarization mode coupling is given a statistical treatment based on the recently proposed principal-states model and the variance is shown to have a linear dependence on length while the probability density function for the delay time approaches a Gaussian shape.
Abstract: Polarization dispersion in single-mode fiber with random polarization mode coupling is given a statistical treatment based on the recently proposed principal-states model. An expression for the ensemble variance of the differential delay time between the principal states of polarization is derived by using coupled-mode theory under the assumption of weak coupling. For long fiber lengths, the variance is shown to have a linear dependence on length while the probability density function for the delay time approaches a Gaussian shape.
Book•
[...]
01 Jan 1988
TL;DR: Physical Explanation of Waveguiding by Single-Mode Fibers by Electromagnetic Fields and Gaussian Beams is given in this paper, where the fundamental fiber mode and higher-order modes are discussed.
Abstract: Physical Explanation of Waveguiding by Single-Mode Fibers.- Electromagnetic Fields.- Gaussian Beams.- The Fundamental Fiber Mode.- Higher-Order Modes.- Launching of Modes.- Radiation from the Fiber End.- Joints Between Fibers.- Spot Size and Width of the Radiation Pattern.- Signal Transmission Through Single-Mode Fibers.- Components for Single-Mode Fibers.- Measuring Techniques.
NEC1
TL;DR: In this article, the authors investigated SBS gain and threshold characteristics with amplitude-shift-keying (ASK), frequency-shift keying (FSK), and phase-shiftkeying modulated lights to estimate the input power limitation.
Abstract: Stimulated Brillouin scattering (SBS) limits the optical power that can be transmitted through a single-mode fiber in long-distance optical communication systems, the authors have investigated SBS gain and threshold characteristics with amplitude-shift-keying (ASK), frequency-shift-keying (FSK), and phase-shift-keying (PSK) modulated lights to estimate the input power limitation set by SBS. It was shown that maximum fiber-input powers or the SBS thresholds for fixed-pattern (1010 . . .) ASK, FSK, and PSK modulated lights are 2, 4, and 2.5 times higher, respectively, than the threshold for unmodulated light. Theoretical predictions were experimentally verified by SBS gain measurements with FSK and PSK modulated lights. The first direct observation of SBS with FSK modulated light pumping is also described. >
TL;DR: The efficiency with which starlight can be coupled into a single-mode fiber optic that is placed in the focal plane of a telescope and the dependence on the f-ratio of the incident beam is explored.
Abstract: We have calculated the efficiency with which starlight can be coupled into a single-mode fiber optic that is placed in the focal plane of a telescope. The calculations are performed for a wide range of seeing conditions, with and without rapid image stabilization, and for a wide range of wavelengths. The dependence of coupling efficiency on the f-ratio of the incident beam is explored. Also, we calculate the coupling efficiency as a function of displacement for a perfect Airy pattern. We have also used a computer program which simulates atmospheric wavefronts to determine the variance of instantaneous coupling efficiency as a function of seeing. In perfect conditions, the maximum efficiency at the LP(11) mode cutoff is 78% due to the mismatch of the Airy pattern and the nearly Gaussian mode of the fiber. Maximum total coupled power is attained at d/r(0) = 4 with rapid image stabilization.
Patent•
17 Aug 1988TL;DR: A moldable fiber-optic plug for retaining optical fibers in a fixed position within a laser catheter is described in this article, where an optically polished tubular moldable plug body is used to secure a plurality of optical fibers within the catheter.
Abstract: A molded fiber-optic plug for retaining optical fibers in a fixed position within a laser catheter is disclosed in which an optically polished tubular moldable plug body is used to secure a plurality of optical fibers within a laser catheter.
TL;DR: RefReflectively monitored Fabry-Perot interferometers which make use of dielectric mirrors in continuous lengths of single mode fiber are characterised for use as temperature and wavelength sensors as discussed by the authors.
Abstract: Reflectively monitored Fabry-Perot interferometers which make use of dielectric mirrors in continuous lengths of single mode fibre are characterised for use as temperature and wavelength sensors.
TL;DR: In this paper, a review of the properties of several mode groups is given, and computed results are shown for a wide range of material properties, including dispersion relations, mode patterns, power relations, and acousto-optic coupling strength.
Abstract: Acoustic modes propagating in cylindrical solid rods are considered. A review of the properties of several mode groups is given, and computed results are shown for a wide range of material properties. The lower mode of each group is relevant for an all-fiber-optic frequency shifter recently demonstrated. For these modes, dispersion relations, mode patterns, power relations, and acoustooptic coupling strength are calculated. Some experimental results are compared with the calculations, and alterations to improve the frequency shifter are proposed. >
TL;DR: In this article, a closed loop system with two integrated optical retarders is described, which has variable eigenmodes, i.e. adjustable birefringence orientation.
Abstract: In coherent optical systems or sensors, polarization matching between the superposed beams must be assured. The tracking range of automatic polarization control systems should be endless, i.e. any resets of finite range retarders, which transform the polarization, should cause no significant intensity losses. A variety of experimental systems including a computer as feedback controller are described. They include the minimum configuration of three fixed eigenmode retarders, i.e. the orientation of birefringence cannot be changed. These retarders are realized by fiber squeezers. Error-tolerant systems which contain more than the minimum number of elements, however, are better suited to cope with time variant retarder transfer functions, etc. A fourth fiber squeezer allows the losses of a nonideal systems to be kept to only 0.07 dB. Finally, for the first time, a closed loop system with two integrated optical retarders is described. These retarders have variable eigenmodes, i.e. adjustable birefringence orientation. An optimization procedure helps to idealize the device behavior. The system has less than 0.15 dB intensity losses, coupling and attenuation not included. >
TL;DR: The analysis shows that the fiber fuse is a new kind of solitary thermal shock wave in whose leading edge the temperature gradients can reach several thousand kelvins per micrometer.
Abstract: Fresh experimental and theoretical results on thermally induced catastrophic breakdown (the fiber fuse) in optical fibers are presented, including the observation that the damage is not always irreversible and an analysis of the complex unsteady absorption–heat-conduction process that controls the effect. Good agreement with experiment is obtained with just two independent parameters. The analysis shows that the fiber fuse is a new kind of solitary thermal shock wave in whose leading edge the temperature gradients can reach several thousand kelvins per micrometer.
TL;DR: In this article, the first mixed-type solutions to the coupled nonlinear Schrodinger equations which govern optical pulse propagation in a birefringent fiber were presented, which are bound states of two solitary waves which separately have constant and uniform orthogonal linear polarizations.
Abstract: We present the first mixed-type solutions to the coupled nonlinear Schr\"odinger equations which govern optical pulse propagation in a birefringent fiber. These represent polarization-modulated pulses which, apart from the absolute phase, propagate unchanged in form. It is shown they are bound states of two solitary waves which separately have constant and uniform orthogonal linear polarizations. Furthermore, there exists a minimum-energy threshold for the formation of these bound states.
Patent•
17 Mar 1988
TL;DR: In this paper, a catheter for shooting a laser beam, comprising an optical fiber contained in a sheath, as well as an optical system, was described, where the optical system obturates the distal end of the sheath and formed a chamber which was in communication with a supply conduit and with a return conduit for an optically neutral cooling fluid.
Abstract: This invention relates to a catheter for shooting a laser beam, comprising an optical fiber contained in a sheath, as well as an optical system, wherein said optical system obturates the distal end of said sheath, and, between the distal end of said optical fiber and said optical system, there is formed a chamber which is in communication with a supply conduit and with a return conduit for an optically neutral cooling fluid.
TL;DR: It is shown that the host glass influences the excited-state absorption spectra and that P(2)O(5)- or A1(2]O(3)-codoped fibers are the preferred choice for 514.5-, 655-, or 807-nm pump wavelengths owing to reduced pump excited- state absorption.
Abstract: Ground-state and excited-state absorption spectra covering the wavelength range of 450–1050 nm are presented for erbium-doped silica fibers with four different core codopants: GeO2, GeO2/B2O3, GeO2/P2O5, and Al2O3. It is shown that the host glass influences the excited-state absorption spectra and that P2O5- or Al2O3-codoped fibers are the preferred choice for 514.5-, 655-, or 807-nm pump wavelengths owing to reduced pump excited-state absorption. However, excited-state absorption is still significant at the 807-nm wavelength. Pump wavelengths of 524, 532, and 980 nm appear ideal because of the strong ground-state absorption and lack of excited-state absorption.
Patent•
27 Jan 1988TL;DR: An optical fiber organizer and splicing arrangement as mentioned in this paper allows storage of variable lengths of surplus fiber in a flexible manner by wrapping multiple loops of fiber around the cylinder circumference and a diameter determined by the fiber bend radius restriction.
Abstract: An optical fiber organizer and splicing arrangement permits storage of variable lengths of surplus fiber. The organizer has a pair of separated cylinders extending from a first rectangular section of a base plate and a splice tray having opposite entrance sides for optical fiber in a second rectangular section. Each cylinder has a prescribed height permitting wrapping of multiple loops of fiber around the cylinder circumference and a diameter determined by the fiber bend radius restriction. The splicing tray is spaced from the base plate to permit passage of optical fiber underneath the splicing tray. The surplus fiber is directed around one or both cylinders and underneath the splicing tray through a plurality of different length passageways so that the varying lengths of optical fiber are stored. Clockwise, counter clockwise and figure eight loops are used so that each optical fiber end is directed to predetermined entrance side of the splicing tray without exceeding the fiber bend radius restriction.
TL;DR: In this paper, the relative merits of three designs of compound optical-fiber-based resonators for application to line narrowing in fiber lasers and demultiplexing in optical-communications systems are discussed.
Abstract: The relative merits of three designs of compound optical-fiber-based resonators for application to line narrowing in fiber lasers and demultiplexing in optical-communications systems are discussed. The three resonator designs are a set of concatenated rings, a three-reflector resonator with loop mirrors, and a fiber Fox–Smith interferometer.
TL;DR: In this article, a fiber-optic sensor has been developed which responds to carbon dioxide at physiologically significant concentrations, based on pH modulation by dissolved carbon dioxide in a sensing layer of fluorescent dye.