Showing papers on "Optical fiber published in 1989"

Nonlinear Fiber Optics

Abstract: Nonlinear fiber optics concerns with the nonlinear optical phenomena occurring inside optical fibers. Although the field ofnonlinear optics traces its beginning to 1961, when a ruby laser was first used to generate the second-harmonic radiation inside a crystal [1], the use ofoptical fibers as a nonlinear medium became feasible only after 1970 when fiber losses were reduced to below 20 dB/km [2]. Stimulated Raman and Brillouin scatterings in single-mode fibers were studied as early as 1972 [3] and were soon followed by the study of other nonlinear effects such as self- and crossphase modulation and four-wave mixing [4]. By 1989, the field ofnonlinear fiber optics has advanced enough that a whole book was devoted to it [5]. This book or its second edition has been translated into Chinese, Japanese, and Russian languages, attesting to the worldwide activity in the field of nonlinear fiber optics.

Formation of Bragg gratings in optical fibers by a transverse holographic method

Abstract: Bragg gratings have been produced in germanosilicate optical fibers by exposing the core, through the side of the cladding, to a coherent UV two-beam interference pattern with a wavelength selected to lie in the oxygen-vacancy defect band of germania, near 244 nm. Fractional index perturbations of approximately 3 x 10(-5) have been written in a 4.4-mm length of the core with a 5-min exposure. The Bragg filters formed by this new technique had reflectivities of 50-55% and spectral widths, at half-maximum, of 42 GHz.

Code division multiple-access techniques in optical fiber networks. II. Systems performance analysis

Abstract: For pt.I see ibid., vol.37, no.8, p.824-33 (1989). In Part I a technique based on optical orthogonal codes was presented to establish a fiber-optic code-division multiple-access (FO-CDMA) communications system. The results are used to derive the bit error rate of the proposed FO-CDMA system as a function of data rate, code length, code weight, number of users, and receiver threshold. The performance characteristics for a variety of system parameters are discussed. A means of reducing the effective multiple-access interference signal by placing an optical hard-limiter at the front end of the desired optical correlator is presented. Performance calculations are shown for the FO-CDMA with an ideal optical hard-limiter, and it is shown that using an optical hard-limiter would, in general, improve system performance. >

Optical solitons in fibers

Abstract: 1. Introduction.- 2. Wave Motion.- 2.1 What is Wave Motion?.- 2.2 Dispersive and Nonlinear Effects of a Wave.- 2.3 Solitary Waves and the Korteweg de Vries Equation.- 2.4 Solution of the Korteweg de Vries Equation.- 3. Lightwave in Fibers.- 3.1 Polarization Effects.- 3.2 Plane Electromagnetic Waves in Dielectric Materials.- 3.3 Kerr Effect and Kerr Coefficient.- 3.4 Dielectric Waveguides.- 4. Information Transfer in Optical Fibers and Evolution of the Lightwave Packet.- 4.1 How Information is Coded in a Lightwave.- 4.2 How Information is Transferred in Optical Fibers.- 4.3 Master Equation for Information Transfer in Optical Fibers: The Nonlinear Schrodinger Equation.- 4.4 Evolution of the Wave Packet Due to the Group Velocity Dispersion.- 4.5 Evolution of the Wave Packet Due to the Nonlinearity.- 4.6 Technical Data of Dispersion and Nonlinearity in a Real Optical Fiber.- 4.7 Nonlinear Schrodinger Equation and a Solitary Wave Solution.- 4.8 Modulational Instability.- 4.9 Induced Modulational Instability.- 4.10 Modulational Instability Described by the Wave Kinetic Equation.- 5. Optical Solitons in Fibers.- 5.1 Soliton Solutions and the Results of Inverse Scattering.- 5.2 Soliton Periods.- 5.3 Conservation Quantities of the Nonlinear Schrodinger Equation.- 5.4 Dark Solitons.- 5.5 Soliton Perturbation Theory.- 5.6 Effect of Fiber Loss.- 5.7 Effect of the Waveguide Property of a Fiber.- 5.8 Condition of Generation of a Soliton in Optical Fibers.- 5.9 First Experiments on Generation of Optical Solitons.- 6. All-Optical Soliton Transmission Systems.- 6.1 Raman Amplification and Reshaping of Optical Solitons-First Concept of All-Optical Transmission Systems.- 6.2 First Experiments of Soliton Reshaping and of Long Distance Transmission by Raman Amplifications.- 6.3 First Experiment of Soliton Transmission by Means of an Erbium Doped Fiber Amplifier.- 6.4 Concept of the Guiding Center Soliton.- 6.5 The Gordon-Haus Effect and Soliton Timing Jitter.- 6.6 Interaction Between Two Adjacent Solitons.- 6.7 Interaction Between Two Solitons in Different Wavelength Channels.- 7. Control of Optical Solitons.- 7.1 Frequency-Domain Control.- 7.2 Time-Domain Control.- 7.3 Control by Means of Nonlinear Gain.- 7.4 Numerical Examples of Soliton Transmission Control.- 8. Influence of Higher-Order Terms.- 8.1 Self-Frequency Shift of a Soliton Produced by Induced Raman Scattering.- 8.2 Fission of Solitons Produced by Self-Induced Raman Scattering.- 8.3 Effects of Other Higher-Order Dispersion.- 9. Polarization Effects.- 9.1 Fiber Birefringence and Coupled Nonlinear Schrodinger Equations.- 9.2 Solitons in Fibers with Constant Birefringence.- 9.3 Polarization-Mode Dispersion.- 9.4 Solitons in Fibers with Randomly Varying Birefringence.- 10. Dispersion-Managed Solitons (DMS).- 10.1 Problems in Conventional Soliton Transmission.- 10.2 Dispersion Management with Dispersion-Decreasing Fibers.- 10.3 Dispersion Management with Dispersion Compensation.- 10.4 Quasi Solitons.- 11. Application of Dispersion Managed Solitons for Single-Channel Ultra-High Speed Transmissions.- 11.1 Enhancement of Pulse Energy.- 11.2 Reduction of Gordon-Haus Timing Jitter.- 11.3 Interaction Between Adjacent Pulses.- 11.4 Dense Dispersion Management.- 11.5 Nonstationary RZ Pulse Propagation.- 11.6 Some Recent Experiments.- 12. Application of Dispersion Managed Solitons for WDM Transmission.- 12.1 Frequency Shift Induced by Collisions Between DM Solitons in Different Channels.- 12.2 Temporal Shift Induced by Collisions Between DM Solitons in Different Channels.- 12.3 Doubly Periodic Dispersion Management.- 12.4 Some Recent WDM Experiments Using DM Solitons.- 13. Other Applications of Optical Solitons.- 13.1 Soliton Laser.- 13.2 Pulse Compression.- 13.3 All-Optical Switching.- 13.4 Solitons in Fibers with Gratings.- 13.5 Solitons in Microstructure Optical Fibers.- References.

Theoretical description of transient stimulated Raman scattering in optical fibers

Abstract: The authors derive a single-wave equation which describes transient stimulated Raman scattering in optical fibers. The equation is valid for forward traveling waves whose bandwidths are less than approximately=1/3 the carrier frequency. It correctly conserves a classical photon number and not the total optical energy as is appropriate for Raman scattering problems. From this equation, the authors derive a formula for the small-signal gain spectrum which includes the effects of Raman scattering, four-wave mixing, and modulational instabilities. Examples of numerical integrations are given which show the generation of short soliton pulses from the nonlinear evolution of a noise band around a continuous wave pump. >

Improved fiber‐optic interferometer for atomic force microscopy

Abstract: A high‐sensitivity fiber‐optic displacement sensor for atomic force microscopy is described. The sensor is based on the optical interference occurring in the micron‐sized cavity formed between the cleaved end of a single‐mode optical fiber and the microscope cantilever. As a result of using a diode laser light source and all‐fiber construction, the sensor is compact, mechanically robust, and exhibits good low‐frequency noise behavior. Peak‐to‐peak noise in a dc to 1 kHz bandwidth is less than 0.1 A. Images are presented demonstrating atomic resolution of graphite and magnetic force imaging of bits written on a magnetic disk.

Refractive index of some mammalian tissues using a fiber optic cladding method.

Abstract: The index of refraction n of the many mammalian tissues is an important but somewhat neglected optical constant. Archival and oral papers have quoted the use of values of n for tissue generally ranging from 1.35 to 1.55. However, these values are frequently without experimental basis. They have arbitrarily used values near that of water, which is a major component of mammalian tissue, or have calculated a theoretical n from the weighted elemental composition of tissue. Since these values have not been precise and little information is available on specific indices for each tissue, a study was undertaken to develop a simple, rapid, and reliable method for the experimental determination of n. This was done using the ubiquitous quartz optical fiber. By substituting the usual cladding found on commercial quartz optics by the tissue in question and utilizing the principle of internal reflection, the value of n for the specific tissue can be calculated. This is done by utilizing the known indices for air and quartz and measuring the angle of the emergent cone of light from the output of the optical fiber. A number of indices for mammalian tissue (bovine, porcine, canine, and human) have been determined at 632.8 nm. With few exceptions, for tissues at this wavelength, n was in the 1.38-1.41 range. The species type did not appear to be a factor. Bovine muscle showed normal dispersion characteristics through the visible wavelengths. The denaturation of tissue was shown to alter significantly the refractive index.

Raman response function of silica-core fibers

Abstract: For analyzing the propagation of ultrashort optical pulses, Raman gain is conveniently described as a response function in the time domain. In this paper we develop the Raman response function for silica-core fibers and use it to study the effect of Raman gain in regimes of normal and anomalous dispersion.

Tensile strain dependence of Brillouin frequency shift in silica optical fibers

Abstract: Brillouin frequency shift in a single-mode optical fiber has been measured as a function of tensile strain. The strain coefficient of normalized Brillouin frequency shift C identical to (dv/sub B//d epsilon )/v/sub B/ is found to be 4.4 for silica fibers. This result shows the potential of Brillouin spectroscopy to evaluate tensile strain in the fiber with the strain resolution of about 2*10/sup -4/. The origin of the large strain coefficient is discussed. >

BOTDA-nondestructive measurement of single-mode optical fiber attenuation characteristics using Brillouin interaction: theory

Abstract: A theoretical investigation of Brillouin optical-fiber time-domain analysis (BOTDA) is described. BOTDA uses Brillouin interaction in optical fibers to analyze the attenuation characteristics of the optical fibers nondestructively. The dynamic range performance of BOTDA is approximately 10-dB greater than that of conventional optical time-domain reflectometry. >

Two-photon absorption as a limitation to all-optical switching.

Abstract: Two-photon absorption can place a fundamental limitation on waveguide all-optical switching devices. We have derived a general criterion to describe this limitation that must be satisfied by all materials. As a specific example, we have experimentally evaluated this criterion for a lead-glass fiber.

Amplification of spontaneous emission in erbium-doped single-mode fibers

Abstract: Amplification of spontaneous emission (ASE) in erbium-doped single-mode fiber amplifiers operating at lambda =1.53 mu m is studied theoretically and experimentally. The ASE noise spectra obtained from the theory are found to be in excellent quantitative agreement with the experimental data. The observed changes in ASE spectral shapes under different population inversion conditions are also explained. The model may be used to evaluate the performance of erbium-doped fiber lasers as well as to assess the noise characteristics of erbium-doped fiber amplifiers as applied to wavelength-division multiplexing optical communications. >

Effects of phase-to-intensity noise conversion by multiple reflections on gigabit-per-second DFB laser transmission systems

Abstract: Large power penalties and bit-error-rate floors have been observed in some Gb/s systems using distributed feedback (DFB) lasers, which could be attributed to interferometric conversion of laser phase noise to intensity noise by multiple reflections at connectors and splices. The authors calculated the power spectral density of the interferometric noise and its impact on system performance as a function of both the magnitude and number of reflections, and they compare the theoretical predictions with experimental results. Their studies indicate that connectors and splices with return losses of more than about 25 dB are required for the reliable operation of Gb/s fiber transmission systems, even if optical isolators are used. >

Optical interconnection network

Abstract: A crossbar switch (500) with input optical fibers (571, . . . 586) and output optical fibers (511, . . . 526) having ends connected to transmitters (551, . . . 554) and receivers 561, . . . 564), respectively, and other ends in linear arrays (545, 546) that are adjacent to linear micro lens arrays (540, 542) and a linear spatial light modulator (530) with light emitted from an input fiber end reflected back into an output fiber end for pixels deflected in one direction in the spatial light modulator (530) and lost for pixels deflected in another direction. Other embodiments include reflection from a pixel directly back into the same fiber which is bifurcated.

Electric current sensors employing spun highly birefringent optical fibers

Abstract: The theory of highly elliptically birefringent fibers fabricated by spinning a linearly birefringent fiber during the draw is described. These fibers are particularly interesting for application as Faraday-effect fiber current monitors, since, in contrast to conventional fibers, they can be wound in small multiturn coils while retaining their sensitivity. The fiber and its application in three optical schemes are modeled using Jone calculus and are also experimentally investigated. A simple optical configuration is proposed, combining the elliptically birefringent fiber and a broad-spectrum light source. An accurate, compact, and robust current monitor is obtained. The sensor is characterized by a measurement repeatability of +or-0.5%, a temperature drift of 0.05%/ degrees C and a sensitivity of 1 mA RMS/Hz/sup 1/2/. Further, the performance of this sensor with optimized fiber length for a given measurement bandwidth is predicted. >

Waveguides and fibers for nonlinear optics

Abstract: We review the operation of, and materials requirements for, a variety of nonlinear-optics guided-wave devices.

Glass waveguides on silicon for hybrid optical packaging

Abstract: Work on deposited glass waveguides on silicon to form waveguides and filters is reviewed. The choice of these particular waveguides makes sense only as part of a consistent approach to optoelectronic packaging. Hybrid optical packaging on silicon (HOPS) is described and briefly compared with other techniques. For these packages, two waveguides were developed: a tight mode waveguide with a silicon nitride rib core for matching a semiconductor laser and a loose mode waveguide with a phosphosilicate glass core for matching an optical fiber. >

High precision optical fiber connectors

Abstract: A duplex fiber optic connector assembly enables mating the fibers of a first multifiber cable with like fibers of a second cable or cables with maximum axial alignment of the respective fiber pairs. An interconnect member receives cable terminating connectors in opposite sides thereof. Each connector carries the fibers of a respective cable in individual ferrules, each ferrule having limited floating mount within the respective connector. The mating pairs of ferrules are received in opposite ends of receptor members each of which has an axially profiled bore adapted to receive the respective ferrules and a profiled outer surface which allows movement about the geometric center of the receptor so as to axially align the bores of the ferrules received therein. Connectors at each end of a predetermined length of fiber optic cable provide a fiber optic extension cord, analogous to the well-known electrical extension cord, for convenient and efficient interconnection between optical signal-using equipments. Small interconnect members receive the connectors of such fiber optic extension cords to allow even wider-ranging interconnections. Wall boxes containing such interconnect members, connected to permanently installed fiber optic cables conveying optical signals from a central optical signal source, allow a user to readily access optical signals by "plugging-in" a connector therein.

Experimental demonstration of optical soliton switching in an all-fiber nonlinear Sagnac interferometer

Abstract: We demonstrate, for the first time to our knowledge, the switching of optical solitons. We observe switching of 93% of the total reflected energy in a partially transmitting integrated fiber loop mirror that makes up the interferometer. This result demonstrates the potential of solitons as the natural bits in ultrafast optical processing.

Soliton trapping in birefringent optical fibers

Abstract: We show experimentally the trapping of orthogonally polarized solitons in birefringent optical fibers with polarization dispersions as high as 90 psec/km. Solitons along two axes of a fiber compensate for the polarization dispersion by shifting their frequencies, and we observe frequency splitting up to 1.03 THz for a polarization dispersion of 80 psec/km. For a 20-m fiber the energy required to compensate for the polarization dispersion is ~84 pJ, and for a 76-m fiber the energy required reduces to ~64 pJ.

1550NM fiber distribution panel

Abstract: Apparatus for selectively interfacing first optical fibers with second optical fibers including a stationary housing having a connector panel and storage cassettes, and a slideable drawer having a splice tray and a fiber and pigtail take-up enclosure.

Optical-fiber-attenuation investigation using stimulated Brillouin scattering between a pulse and a continuous wave.

Abstract: A new technique for measuring optical-fiber-attenuation characteristics is described The technique uses stimulated Brillouin scattering in the fiber between a counterpropagating pulsed pump wave and a cw Stokes probe wave Fiber attenuation is estimated nondestructively from amplification of the probe wave through stimulated Brillouin scattering Experiments with a 52-km-long single-mode fiber reveal that the output signal is approximately 100 times that of the Rayleigh backscattered signal observed in conventional optical time-domain reflectometry The signal fluctuation due to polarization-dependent Brillouin gain is successfully removed by polarization averaging

Efficient Er3+‐doped optical fiber amplifier pumped by a 1.48 μm InGaAsP laser diode

Abstract: Optical gain characteristics of an Er3+ ‐doped silica fiber have been studied by end pumping with a 1.48 μm InGaAsP high‐power laser diode. A gain as high as 12.5 dB was obtained for an absorbed pump power of 16 mW with a 3‐m‐long fiber. By constructing an Er3+ fiber ring cavity with a 3 dB single‐mode fiber coupler, we have obtained continuous wave laser oscillation at a wavelength of 1.553 μm.

Modified optical frequency domain reflectometry with high spatial resolution for components of integrated optic systems

Abstract: An apparatus which allows detection of scatterers and faults as well as measurement of reflections in fiber or integrated optic devices and systems with a spatial resolution in the region of 10-100 mu m is discussed. The dynamic range is sufficient to detect reflection with a reflection coefficient down to 10/sup -10/. The system uses a modified optical frequency domain reflectometry (OFDR) technique whereby signal light and local oscillator light are coupled into the waveguide under test from opposite directions. The measurement principle requires the wavelength of the light source to be swept continuously up or down. It is shown that the experimental relationship between frequency shift and waveguide length is in fairly good agreement with the theoretical estimate. Polarization-sensitive experimental results are given for reflection factors in short, side-polished polarization-maintaining fibers. >

Light emitting panel assemblies and method of making same

Abstract: Light emitting panel assemblies and method of making same include one or more layers of woven fiber optic material having disruptions or bends at discrete locations along the length of the fibers to allow light to be emitted therefrom. Only selected areas of the disruptions or bends are coated with a suitable coating material that has a refractive index that changes the attenuation of the light emitted from the selected areas. The coating material may be applied to the selected areas using one or more carrier members which become part of the panel. Alternatively, a non-permanent carrier such as a roller may be used to coat selected areas of the optical fiber disruptions or bends with the coating material after the weaving process.

Method of producing elliptic core type polarization-maintaining optical fiber

Abstract: A method of producing an elliptic core type polarization-maintaining optical fiber comprises the steps of providing a glass rod comprising a cladding glass layer around the periphery of a core glass layer, the cladding glass layer having a softening point higher than the softening point of the core glass layer, removing two side surface portions of the glass rod by machining along the axial direction of the glass rod to form a machined rod noncircular in cross section, outside depositing fine silica glass particles on the periphery of the machined rod, followed by sintering to provide a support glass layer having a softening point higher than the softening point of the cladding glass layer, and drawing the thus obtained glass rod body as an optical fiber preform. Since the portion for constituting the core of the optical fiber is formed by machining, the core is permitted to have a high ellipticity. An optical fiber with the desired size and birefringence index is obtained by regulating the conditions of production.

Semiconductor laser module

Abstract: A semiconductor laser module comprises a semiconductor laser device, an optical fiber, and a lens for coupling light emitted from the semiconductor laser device to the optical fiber There is provided a metal base having a flat portion and a pipe portion in a metal case The semiconductor laser device is mounted on a chip carrier which is mounted on the flat portion of the metal base The lens is fixed in the inside of the pipe portion of the metal base The optical fiber is protected at one end by a ferrule which is fixed to the pipe portion of the metal base A device such as a monitor photodiode and a thermistor may be mounted on the flat portion of the metal base The flat portion of the metal base may be formed with a concave portion of an area smaller than an area of the bottom of the chip carrier The chip carrier is soldered to the flat portion of the metal base by a low temperature solder to provide thermal connection therebetween, and by a spot welding at a point other than the soldered portion of the low temperature solder

Connector holders and distribution frame and connector holder assemblies for optical cable

Abstract: A planar connector holder for optical fibers having storage compartments for incoming fibers and a mounting region for connectors to outgoing fibers. Two storage compartments lie back-to-back on each side of a planar base of the holder, the compartments being interconnected for fiber to pass from compartment-to-compartment. The mounting region and the storage compartments are aligned from end-to-end of the holder. With connector mounts mounted in the mounting region, the mounts lie in planes common with the two storage compartments in a depth direction of the holder. Also included is a distribution frame and holder combination in which the holders are mounted in two banks with patch cords extending between the banks and selectively between connectors.

Femtosecond passively mode-locked Ti:Al(2)O(3) laser with a nonlinear external cavity.

Abstract: Ultrashort pulses are generated in a Ti:Al2O3 laser by using a coupled nonlinear external cavity. The external cavity uses self-phase modulation in an optical fiber to achieve passive mode locking without the need for synchronous pumping or acousto-optic modulation. A stable train of chirped 1.4-psec pulses is generated. After dispersive compensation, pulses as short as 200 fsec are obtained.

Efficient N*N star couplers using Fourier optics

Abstract: A technique for constructing an efficient N*N star coupler with large N at optical frequencies is described. The coupler is realized in free space using two arrays, each connected to N single-mode fibers. The highest efficiencies are obtained using a planar arrangement of two linear arrays separated by a dielectric slab serving as free-space region. The coupler is suitable for mass production in integrated form, with efficiencies exceeding 35%. >