Showing papers on "Optical fiber published in 1986"

Long-wavelength semiconductor lasers

Abstract: The current status and future applications to lightwave transmission of long-wavelength semiconductor lasers emitting near 1.3 and 1.55- mu m are described. Bit-error-rate curves for a transmission experiment at 8 Gb/s over 76 km of fiber are shown, and schematics of a high-speed distributed feedback laser and a multielectrode distributed Bragg reflector laser are presented. >

Theory of the soliton self-frequency shift.

Abstract: Raman effects cause a continuous downshift of the mean frequency of pulses propagating in optical fibers. For solitons in silica fibers, the effect varies roughly with the inverse fourth power of the pulse width. At 1.5-μm wavelength in a fiber with 15 psec/nm/km time-of-flight dispersion, a soliton of 250-fsec duration is predicted to shift by its own spectral width after about 100m of propagation. The theory agrees well with recent measurements.

Observation of Berry's topological phase by use of an optical fiber.

Abstract: We report the first experimental verification of Berry's topological phase. The key element in the experiment was a single-mode, helically wound optical fiber, inside which a photon of a given helicity could be adiabatically transported around a closed path in momentum space. The experiment confirmed at the classical level that the angle of rotation of linearly polarized light in this fiber gives a direct measure of Berry's phase. The topological nature of this effect was also verified, i.e., the rotation was found to be independent of deformations of fiber path if the solid angle of the path in momentum space stayed constant.

Polarization-maintaining fibers and their applications

Abstract: Polarization-maintaining fibers and their applications are reviewed. The classification of high-birefringent fibers and low-birefringent fibers and their fabrication methods and characteristics are discussed in Section II. Analytical methods and numerical methods for fiber design on the birefringence are presented in Section III. Degradation factors of polarization maintenance expressed as crosstalk or mode-coupling parameters caused by internal origins such as structural imperfections, wavelength, and nonlinear effects, and by external origins such as temperature fluctuations, mechanical perturbations, and electromagnetic effects, are discussed in Section IV. Characterization methods on beat length, mode coupling, stress distribution, and mechanical strength are presented in Section V. Applications to the fiber devices and nonlinear effects, and splicing methods for the polarization-maintaining fibers are described in Sections VI and VII.

Dye laser pumped by Nd:YAG laser pulses frequency doubled in a glass optical fiber.

Abstract: Efficient frequency doubling of a cw Q-switched and mode-locked Nd:YAG laser has been observed in commercial single-mode optical glass fibers. Pulses of duration ~55 psec and intensities as high as ~0.55 kW were produced at 0.53 μm. The maximum peak power-conversion efficiency measured was ~3%. The frequency-doubled light generated in the glass fibers was sufficient to pump a commercial Rh6G dye laser with ~19% efficiency at 570 nm.

Broad-band parametric deamplification of quantum noise in an optical fiber.

Abstract: Broad-band squeezed states of light are generated by forward nondegenerate four-wave mixing in a single-mode optical fiber cooled below 4.2 K. The minimum total noise level was (12.5 \ifmmode\pm\else\textpm\fi{} 0.5)% below the standard quantum limit.

Nonlinear pulse propagation in the neighborhood of the zero-dispersion wavelength of monomode optical fibers

Abstract: Nonlinear pulse propagation is investigated in the neighborhood of the zero-dispersion wavelength in monomode fibers. When the amplitude is sufficiently large to generate breathers (N > 1 solitons), it is found that the pulses break apart if λ – λ0 is sufficiently small, owing to the third-order dispersion. Here λ0 denotes the zero-dispersion wavelength. By contrast, the solitary-wave (N = 1) solution appears well behaved for arbitrary λ – λ0. Implications for communication systems and pulse compression are discussed.

Optical Fiber Communications: Principles and Practice

Abstract: (1986). Optical Fiber Communications: Principles and Practice. Optica Acta: International Journal of Optics: Vol. 33, No. 6, pp. 685-685.

Soliton propagation in long fibers with periodically compensated loss

Abstract: With computer simulation, we study soliton propagation in an all-optical, long-distance communications system where fiber loss is periodically compensated by Raman gain We find that distortion of the transmitted pulses from true solitons shows a peak near z_{0} = L/8 where L and z 0 are the amplification and soliton periods, respectively We also describe optimal system design based on the exceptional pulse stability and low soliton powers obtained in the region z_{0} \gg L/8 Typical amplification periods are in the range 30-50 km, pump powers are less than 100 mW, and for bit rates in the 10 GHz range, time average signal powers are at most a few milliwatts The single-channel rate-length product for error rate less than 10-9is \sim29 000 GHz Km Finally, we show that in the gain-compensated system with wavelength multiplexing, soliton-soliton collisions produce random modulation of individual pulse velocities Nevertheless, multiplexing can yield rate-length products greater than 300 000 GHz km

All-fiber acousto-optic frequency shifter

Abstract: An all-fiber-optic frequency shifter is demonstrated that uses mode coupling between the LP(01) and LP(11) modes by a traveling acoustic flexural wave guided along the optical fiber. The input and output leads of this frequency shifter are single-mode fibers. Unity mode-conversion efficiency for cw operation is achieved at 8-MHz frequency shift with about 0.25 W of electrical input power. Carrier and image sideband suppression of 15 and 35 dB, respectively, are demonstrated.

Optical fiber distribution apparatus

Abstract: The present invention organizes optical fibers from a trunk cable for connection to fibers from various distribution cables. The apparatus includes a housing having a plurality of trays swingable from a storage position inside the housing to an access position in front of the housing. Each tray includes a spool for holding excess fiber from the trunk cable and a spool for holding fiber from a pigtail cable. In addition, various routing paths are provided to include a path for holding excess fiber from a distribution cable of a pigtail cable leading to a distribution cable. Connections between the fiber of the trunk cable and the pigtain cable and between the pigtail cable and the jumper leading to the distribution cable are attached to the tray and readily movable between the storage and access position. The apparatus may also be used simply to store fiber.

Electromagnetic Principles of Integrated Optics

Abstract: Using optics to present electromagnetic theory, Electromagnetic Principles of Integrated Optics is a radical departure from other texts and a unified and comprehensive introduction to the field of integrated optics. All the fundamental concepts and principles of guided wave optics are developed from Maxwell's equations. From this perspective, the study of the slab and rectangular dielectric waveguide replaces that of the parallel plate and rectangular mentalic waveguide, the optical fiber that of the coaxial transmission line, radiation losses that of conduction losses, and aperture diffraction that of antenna radiation. This complete guide gives you clear coverage of 2- and 3-dimensional optical waveguides, optical fibers, prism and dielectric waveguide couplers, waveguide filters, grating reflectors and optical spectrum analyzers. You will find new approaches to topics such as dielectric waveguides, radiation modes and WKB theory. Electromagnetic Principles of Integrated Optics is carefully structured so that all material is developed from first principles. Sophisticated concepts such as the Goos-Haenchen shift, radiation modes, Bragg scattering of guided modes and optical fiber mode theory have a firm foundation and are made easily understandable. Problems and worked-out examples reinforce the material and are good for self-study. For reference, as a problem-solver, or for self-study. The book provides many of the concepts and mathematical tools necessary to analyze realworld guided wave optics problems.

Polymer Modification of Fiber Optic Chemical Sensors as a Method of Enhancing Fluorescence Signal for pH Measurement

Abstract: The authors have prepared a pH fiber optic sensor based on fluorescence intensity. Fluoresceinamine is incorporated into an acrylamide-methylenebis(acrylamide) copolymer that is attached covalently to a surface-modified glass fiber via thermal or photopolymerization. The sensor gives instantaneous responses and reversible measurements over the pH range of 4.0-8.0 with signal-to-noise ratios of typically 275/1. The results indicate that specific fiber optic chemical sensors can be miniaturized and still retain sufficient signal intensity and stability.

Generation of subpicosecond solitonlike optical pulses at 0.3 THz repetition rate by induced modulational instability

Abstract: We report the generation of 0.5 ps full width at half‐maximum optical pulses at >0.3 THz (tunable) repetition rate via an induced modulational instability in a single‐mode fiber. A 1.319‐μm neodymium:yttrium aluminum garnet laser is chosen as the carrier wave and the initial modulation on this carrier is introduced by mixing it with an external‐grating‐cavity InGaAsP laser. The use of this all‐optical modulating scheme and the nonlinear optical propagation effect in fiber (i.e., modulational instability) allows one to reach into the terahertz regime, which is about two orders of magnitude beyond the fastest data limited by the finite response of electronics.

Dielectric-fibre surface waveguides for optical frequencies

Abstract: A dielectric fibre with a refractive index higher than its surrounding region is a form of dielectric waveguide which represents a possible medium for the guided transmission of energy at optical frequencies. The particular type of dielectric-fibre waveguide discussed is one with a circular cross-section. The choice of the mode of propagation for a fibre waveguide used for communication purposes is governed by consideration of loss characteristics and information capacity. Dielectric loss, bending loss and radiation loss are discussed, and mode stability, dispersion and power handling are examined with respect to information capacity. Physicalrealisation aspects are also discussed. Experimental investigations at both optical and microwave wavelengths are included.

Ultrafast All-Optical Synchronous Multiple Access Fiber Networks

Abstract: Two synchronous multiple access schemes, TDMA and CDMA, are proposed for fiber optic networks using optical signal processing. Network synchronization is achieved by using a central modelocked laser which also serves as the source for each station. The data are converted into a high-bandwidth optical signal using electrooptic modulators. The accessing schemes use optical fiber delay lines. The feasibility of these schemes is discussed.

A review of single-mode fibers with modified dispersion characteristics

Abstract: Standard first-generation single-mode fibers are optimized for operation at a wavelength of 1.3 μm, where they exhibit zero dispersion. By modifying the fiber design it is possible to shift the zero dispersion wavelength to 1.55 μm, where the lowest losses occur in silica-based fibers. Advanced fiber structures can also be designed such that relatively flat dispersion spectra can be achieved over a wide range of wavelengths. In this paper, the theoretical and practical attempts to develop advanced fiber designs have been reviewed.

Highly selective evanescent modal filter for two-mode optical fibers.

Abstract: Efficient and selective coupling between a single-mode fiber and the LP11 mode of a double-mode fiber is demonstrated in an evanescent directional coupler. With greater than 90% coupling to the LP11 mode, suppression of the coupled power to the lower-order LP01 mode was measured to be at least 24 dB. This device has application as a modal filter for the construction of in-line all-fiber optical components.

Fiber-optic modal coupler using periodic microbending.

Abstract: An efficient LP01 to LP11 modal coupler using periodic microbends, spaced by a beat length between the modes, was built and tested. The optical-wavelength dependence of the device is investigated, as are the polarization characteristics and the LP mode approximation. Finally, the loss of the modal coupler was measured as a function of wavelength.

Fiber optic probe for quantification of colorimetric reactions

Abstract: A fiber optical probe (12) for colorimetric measurement of chemical properties suitable for the insertion into living tissue. A chemical to be colorimetrically measured is introduced into a sample chamber (22) on the side of the probe (12) near the probe tip (20). A colorimetric substance contained in the sample chamber (22) changes colors in response to chemical properties of the chemical to be colorimetrically measured, thereby changing the amount of light transmitted through the sample chamber (22) by the optical fibers (10, 12).

Fiber optic connector assembly and wall outlet thereof

Abstract: A fiber optic connector assembly comprises a housing member having a passageway extending therethrough. A receptacle connector member is latchably mounted in the passageway and has therein fiber optic connectors terminated to ends of fiber optic transmission members and fiber optic cables. The fiber optic connectors are mounted in the receptacle connector member as spring-biased connectors with profiled resilient front ends of the connectors disposed in profiled bores of alignment ferrules that are floatingly mounted in the receptacle connector member. A plug connector member has mounted therein spring-biased fiber optic connectors terminated to ends of fiber optic transmission members. Latch members on the plug connector member latchably secure the plug connector member in the housing member with profiled resilient front ends of the fiber optic connectors being disposed in the profiled bores of the alignment ferrules thereby connecting the respective fiber optic transmission members together under spring forces.

Bend loss measurements on high numerical aperture single-mode fibers as a function of wavelength and bend radius

Abstract: The results of an investigation into the bend loss as a function of wavelength for single-radius bends in monomode fibers are given. The fibers considered have a high numerical aperture and a protective coating which has a refractive index greater than that of the cladding. For these fibers the pure bend loss is shown to be the dominant loss mechanism over the wavelength range 633-1152 nm. In addition, oscillations in the loss are observed as the bend radius is varied at the longer wavelengths. These oscillations are shown to result from the coupling of light under weak coupling conditions from a whispering gallery mode in the cladding formed by the pure bend loss, to the fundamental mode in the core. An expression is derived which relates the bend radius at which the minima in the oscillations occur to the fiber parameters and a qualitative explanation is given for the reduction in the oscillation amplitude as the bend radius and wavelength are decreased. A criterion is identified for assessing the strength of the coupling between the whispering gallery mode and fundamental mode. Using this criterion the attenuation coefficient of the pure bend loss at which a transition from weak to strong coupling occurs is determined and is found to agree with observations. The effect of the coupling strength between the whispering gallery mode and the fundamental mode on the characteristics of the pure bend loss is discussed. Finally, possible applications arising from the results of this work are identified.

Experimental observation of polarization instability in a birefringent optical fiber

Abstract: We present the first experimental demonstration of spatial instability in the nonlinear evolution of the state of polarization of an intense light beam in a birefringent Kerr‐like medium. As the peak power crosses the threshold for the instability, we observed strong intensity‐dependent power transfer between the two counter‐rotating circularly polarized waves propagating along a birefringent optical fiber. The experimental results agree well with the theory.

Fabrication and characterization of low-loss optical fibers containing rare-earth ions

Abstract: Low-loss fibers containing rare-earths have been produced with high absorption levels in the visible and near infrared regions. Although containing relatively large quantities of rare-earth impurity dopants, the fibers possess low-loss windows where the attenuation is similar to that observed in undoped fibers. This attribute makes the fibers attractive for use in long distributed sensors, as well as low-threshold fiber lasers. Fiber characteristics relevant to these two applications are uniformity of dopant incorporation, absorption and fluorescence spectra, and fluorescence lifetime. These measurements are presented, together with their respective temperature dependences. The fiber fabrication method is described and results given for Nd3+-, Er3+-, and Tb3+-doped fibers.

Quantum nondemolition detection of optical quadrature amplitudes.

Abstract: In an optical fiber, nonlinear optical interactions couple the sideband modes of two strong pump waves at different frequencies just as required for a quantum nondemolition measurement. Experimental measurements demonstrate that 37% of the rms phase fluctuations of one wave are caused by the quantum amplitude fluctuations of the other.

Tunable single-mode fiber lasers

Abstract: Tunable laser action has been obtained in Nd3+- and Er3+-doped single-mode fiber lasers. In the case of the Nd3+-doped fiber, an extensive tuning range of 80 nm has been achieved. Tunable CW lasing also has been observed for the first time in an Er3+-doped fiber laser, which has an overall tuning range of 25 nm in the region of \lambda = 1.54 /mu m.

Side-hole fiber for fiber-optic pressure sensing.

Abstract: An optical fiber whose structure is similar to that of the PANDA fiber, but with two open channels in the place of the stress members, is investigated. Variations of the internal or external gas pressure permit tuning of the fiber birefringence (10−4 rad m−1 Pa−1) over a wide range, including sign reversal, and application as a pressure sensor.