Showing papers on "Single-mode optical fiber published in 1991"
TL;DR: In this paper, an analytical characterization of polarization dispersion measurements is presented, where the authors report the solution of Poole's stochastic dynamical equation for the evolution of the dispersion vector with fiber length.
Abstract: An analytical characterization of polarization dispersion measurements is presented. The authors report the solution of Poole's stochastic dynamical equation for the evolution of the polarization dispersion vector with fiber length. The authors extend this to a more complete description by considering small, second-order dispersion effects through the frequency derivative of the dispersion vector. The complete analytical solution is seen to accord with what were originally empirically derived features of the joint probability distribution of the polarization dispersion vector and its frequency derivatives. Among the analytically determined properties are the Gaussian probability densities of the three components of the dispersion vector, and the hyperbolic secant (soliton shaped) probability densities of the components of the derivative of the dispersion vector. >
526 citations
01 Oct 1991
TL;DR: In this article, two complementary delineation criteria are presented which provide guidelines to the design of relatively short, low-loss tapered fibres and devices, which are used to explain anomalous loss effects in depressed-cladding and W-fibres, as well as the difficulty in fabricating low loss devices by tapering such fibres.
Abstract: Two complementary delineation criteria are presented which provide guidelines to the design of relatively short, low-loss tapered fibres and devices. They are used to explain anomalous loss effects in depressed-cladding and W-fibres, as well as the difficulty in fabricating low-loss devices by tapering such fibres. Practical application of the criteria to couplers, beam expanders and abrupt taper filters is summarised. The accompanying paper provides both experimental and theoretical justification for the delineation criteria.
447 citations
TL;DR: In this paper, the system fading caused by polarization-mode dispersion was investigated at 1.7 Gb/s using highly-birefringent, dispersion-shifted fiber at a fixed receiver power.
Abstract: System fading caused by polarization-mode dispersion is investigated at 1.7 Gb/s using highly-birefringent, dispersion-shifted fiber at 1.55 mu m. The observed fading, which is manifested by random fluctuations of the bit error rate for a fixed receiver power, is observed to depend on the environmental conditions of the fiber, with the time constant for fading varying from minutes to hours depending on the rate of change of the ambient temperature. The mean dispersion penalty inferred from the observed fluctuations in the bit error rate is consistent with a square-law dependence on the polarization-mode dispersion for small penalties. >
273 citations
TL;DR: In this article, the steady-state coupled-mode equations that govern the nonlinear parametric interaction of a central-frequency wave with a pair of upshifted and downshifted sidebands in isotropic single-mode optical fibers are presented.
Abstract: Exact solutions are presented to the steady-state coupled-mode equations that govern the nonlinear parametric interaction of a central-frequency wave with a pair of upshifted and downshifted sidebands in isotropic single-mode optical fibers. This solution accounts for pump depletion as well for as a possible phase mismatch among the waves. The existence is predicted of eigensolutions propagating unchanged along the fiber, which may be either spatially stable or spatially unstable, depending on the total power and the propagation-constant mismatch. The presence of spatially unstable eigensolutions dramatically affects the power exchange among the three waves. The physical implications of this instability for the frequency-conversion process, as well as its potential application to all-optical switching, are discussed.
248 citations
Journal Article•
TL;DR: In this paper, periodic phase changes in the 10−6 -rad region were induced and detected in a single-mode all-fiber Mach-Zehnder interferometer by stretching the fiber with a piezoelectric cylinder driven at frequencies between 40 and 10−4 Hz.
Abstract: Periodic phase changes in the 10(-6) -rad region have been induced and detected in a single-mode all-fiber Mach- Zehnder interferometer by stretching the fiber with a piezoelectric cylinder driven at frequencies between 40 and 10(4) Hz.
191 citations
TL;DR: In this article, a model for PMD with random mode coupling was developed, and an explicit equation for the time-of-flight distribution was presented, and the coupling length on the order of 20-30 m was estimated.
Abstract: Polarization mode dispersion (PMD) in short and long single-mode fibers was measured by a polarization-maintaining Michelson interferometer. A nonnegligible PMD was found in some standard fibers. The sensitivity enables PMD to measure the bend-induced PMD of a fiber rolled on a 28-cm diameter drum. A theoretical model for PMD with random mode coupling is developed, and an explicit equation for the time-of-flight distribution is presented. Comparison between measurements on short and long fibers with residual birefringence leads to an estimation of the coupling length on the order of 20-30 m. >
187 citations
TL;DR: In this paper, the performance of a very long, single-channel optical fiber system operating very close to the zero-dispersion wavelength of the fiber was investigated by means of computer simulations.
Abstract: The author investigates, by means of computer simulations, the performance of a very long, single-channel optical fiber system operating very close to the zero-dispersion wavelength of the fiber. Fiber losses are compensated by optical amplifiers. The optical signal is filtered after each amplifier, is passed through a final optical filter prior to square-law detection, and is finally filtered electrically. It is found that such a system does not work well if the fiber dispersion is strictly constant and if the carrier wavelength of the modulated signal coincides with the zero-dispersion wavelength of the fiber. As a result, the optical signal spectrum spreads to many times its initial width so that power is lost in the optical filters and the signal-to-noise ratio is degraded by the need for admitting a wider band of noise to the receiver. >
185 citations
TL;DR: In this article, a method for fabrication of a novel type of optical fiber with dispersion varying along the fiber length is described, which takes into account the calculated dependence of fiber dispersion on fiber core diameter for the measured profile of the preform and the desirable dispersion dependence on fiber length.
Abstract: A method for fabrication of a novel type of optical fiber with dispersion varying along the fiber length is described. The method takes into account the calculated dependence of fiber dispersion on fiber core diameter for the measured profile of the preform and the desirable dispersion dependence on the fiber length. The main optical parameters of the drawn fiber are theoretically studied and experimentally measured. The fibers are of great interest for nonlinear fiber optics. Such applications of the fibers, such as high-quality soliton pulse compression, soliton pulsewidth stabilization through compensation of losses, and generation of a high-repetition-rate train of practically uninteracting solitons, are considered. >
184 citations
TL;DR: In this article, an extended nonlinear Schrodinger equation was used to analyze the modulation instability in the region of the minimum group-velocity dispersion, and it was shown that the critical modulation frequency saturates at a value determined by the fourth-order dispersion.
Abstract: Modulation instability in the region of the minimum group-velocity dispersion is analyzed by means of an extended nonlinear Schr\"odinger equation. It is shown that the critical modulation frequency saturates at a value determined by the fourth-order dispersion. Experimental results demonstrate the viability of generating a train of femtosecond pulses with repetition rates of a few terahertz in reasonable agreement with the theory.
155 citations
TL;DR: A single-mode fiber is employed as a detector in a confocal scanning optical microscope instead of a pinhole and its optical property is studied.
Abstract: A single-mode fiber is employed as a detector in a confocal scanning optical microscope (CSOM) instead of a pinhole and its optical property is studied. The optical system is always coherent, which is fundamentally different from the CSOM with a finite-sized pinhole. The coherent transfer function and the axial response are calculated. Experimentally, the coherent image is taken and the axial response is also measured.
153 citations
TL;DR: In this paper, Annealing procedures that greatly reduce linear birefringence in single-mode fiber coils are described, and they have been successfully applied to coils ranging from 5 mm to 10 cm in diameter and up to 200 or more turns.
Abstract: Annealing procedures that greatly reduce linear birefringence in single-mode fiber coils are described. These procedures have been successfully applied to coils ranging from 5 mm to 10 cm in diameter and up to 200 or more turns. They involve temperature cycles that last 3-4 days and reach maximum temperatures of about 850 degrees C. The residual birefringence and induced loss, are minimized by proper selection of fiber. The primary application of these coils is optical fiber current sensors, where they yield small sensors that are more stable than those achieved by other techniques. A current sensor with a temperature stability of +8.4*10/sup -5//K over the range from -75 to +145 degrees C has been demonstrated. This is approximately 20% greater than the temperature dependence of the Verdet constant. Packaging degrades the stability, but a packaged sensor coil with a temperature stability of about +1.6+10/sup -4//K over the range from -20 to +120 degrees C has also been demonstrated. >
TL;DR: In this paper, a helical-grating geometry for coupling the spatial modes in a two-mode fiber was investigated, and the feasibility of making fiber grating filters based on this geometry was investigated.
Abstract: The authors investigate a helical-grating geometry for coupling the spatial modes in a two-mode fiber. The feasibility of making fiber grating filters based on this geometry is investigated. By adding mode strippers at the input and output of a helical-grating spatial-mode coupler, an optical notch filter is demonstrated with 0.3-dB waveguide loss, 24-dB extinction, and 24-nm spectral width. The effect of small ellipticity in the fiber core is also investigated, and it is shown that polarization-insensitive coupling can be achieved in a fiber with a sufficiently circular core. >
TL;DR: In this paper, a single-mode optical fiber that transmits one and only one polarization state of the fundamental mode over a broad wavelength band (13%) is reported, which is attributed to the fiber's refractive-index profile, which mathematically allows only a single polarization state to cutoff.
Abstract: The authors report on a single-mode optical fiber that transmits one and only one polarization state of the fundamental mode over a broad wavelength band (13%). The good broadband performance is attributed to the fiber's refractive-index profile, which mathematically allows only one polarization state to cutoff. The authors discuss general design principles and show that the mode field diameter is a qualitative indicator of the fiber's performance. The fiber's guided polarization state is similar to the fundamental mode of a step-index fiber in its low attenuation, 5.5 dB/km, and small mode diameter, 5.8 mu m (both measurements at 840 nm). Most important, the fiber shows a broad single polarization band, 13%, a feature well described by the change in mode field diameter with wavelength of an ideal, circularly symmetry, W-profile fiber. >
TL;DR: In this paper, the relation between a 3D state of strain and the optical phase retardation in a single mode optical fiber is formalized by drawing together classical three-dimensional crystal optics and classical waveguide theory.
Abstract: The relation between a three-dimensional state of strain and the optical phase retardation in a single mode optical fiber is formalized by drawing together classical three-dimensional crystal optics and classical waveguide theory. Neumann's strain optic relations are described in a form usable in optical fiber sensor design. These relations are then combined with weakly guiding fiber theory to develop an integral which relates the optical phase shift in a structurally embedded interferometric optical fiber strain sensor to the induced three-dimensional strain field. This process leads to a previously undisclosed, additional waveguide dispersion term which contributes on the same order to the total strain induced phase retardation as does the term derived by Butter and Hocker (1978). Still, however, waveguide dispersion effects are found to be negligibly small, even in three- dimensional loading. Butter and Hocker's equation and the complete phase-strain model developed herein can give very similar results...
TL;DR: In this article, the fabrication and characteristics of gain-coupled 1.55-mu m GaInAlAs quantum-well metal-clad ridge-waveguide distributed-feedback lasers are discussed.
Abstract: The fabrication and characteristics of gain-coupled 1.55- mu m GaInAlAs quantum-well metal-clad ridge-waveguide distributed-feedback lasers are discussed. The gain-coupling mechanism was provided by a thin ternary loss grating layer with an estimated gain-coupling strength of about 30/cm. For as-cleaved devices, the single-mode yield was as high as 70 and 95% for 600- and 800- mu m-long devices, respectively. Typical threshold currents were 40 and 55 mA, respectively. Both the high single-mode yield and the pronounced asymmetric spectra were calculated theoretically and give a strong indication that a significant amount of gain coupling was realized in the laser structure. For a 600- mu m-long device, a continuous-wave (CW) output power of 10 mW and a minimum linewidth of 1.6 MHz were measured. >
TL;DR: In this article, a singlemode fused biconical coupler for polarization beamforming is described and a usable spectral window as broad as 17 nm with an extinction ratio smaller than -15 dB for both output fibers is obtained.
Abstract: A single-mode fused biconical coupler for polarization beamsplitting is described. In the coupling region, standard communication fibers are used. The output fibers are polarization-maintaining. To stop the coupler drawing process accurately, the degree of polarization is measured during the drawing and is used as a criterion. Losses of 0.2 dB are typical, and a minimum extinction ratio of -27 dB is achieved. A usable spectral window as broad as 17 nm with an extinction ratio smaller than -15 dB for both output fibers is obtained. Any specified wavelength for the minimum of the extinction ratio is reached within +or-3 nm. >
TL;DR: In this article, a new research area called "dry hydrodynamics" was proposed to test many conjectures formulated for fluids or other nonlinear field problems, which filled the gap between the single mode dynamics and the many domain turbulent-like behavior, which so far was unavailable for a radiation field.
TL;DR: The basic theory of monolithic 1 x 7 couplers is presented, and it is shown that to obtain an equal power split between the center and outer fibers it is necessary to control carefully the degree of fusion of the structure.
Abstract: The basic theory of monolithic 1 × 7 couplers is presented. The results of fabricating eighty-two devices are described, and the steady improvement in achieved device performance is shown leading to the fabrication of a controlled batch of eleven devices. These devices have excess losses of <0.1 dB together with good coupling uniformity to the seven output fibers. Maximum insertion losses are all around 10 dB or less, which is seen to compare favorably with devices obtained by concatenating 2 × 2 couplers. It is shown that to obtain an equal power split between the center and outer fibers it is necessary to control carefully the degree of fusion of the structure. An analysis of this coupling behavior is presented.
TL;DR: In this paper, the authors studied the dynamical effects induced by a squeezed vacuum field interacting with the atoms of a standard single mode optical bistable system and showed that by varying the relative phase between the squeezed vacuum and the coherent input light one can force the system to switch from a low to a high transmission state and vice versa.
Patent•
AT&T1
TL;DR: In this paper, a wavelength selective structure is coupled to an adiabatic Y-coupler via a multimode section which supports both symmetric and antisymmetric modes.
Abstract: A wavelength selective structure is coupled to an adiabatic Y-coupler via a multimode section which supports both symmetric and antisymmetric modes. One single mode branch of the coupler converts guided light to a symmetric mode, whereas the other single mode branch converts guided light to an anti-symmetric mode. The structure, which includes a pair of single mode waveguide arms coupled to the common section and a reflection device (such as a grating or ROR) located in each arm, converts reflected light from a symmetric mode to an anti-symmetric mode and conversely. Applications described include a channel dropping filter and channel balancing apparatus for WDM systems, and a dispersion compensator for fiber optic systems.
TL;DR: In this article, a novel method for selective generation of singlemode acoustic waves in multimode media has been developed using a laser beam scanned at the phase velocity of a specified mode.
Abstract: A novel method for selective generation of single‐mode acoustic waves in multimode media has been developed using a laser beam scanned at the phase velocity of a specified mode. In dispersive media, the acoustic frequency can be varied by changing the scanning velocity. The number of carriers in the generated wave packet is proportional to the difference between the phase and the group velocities. These features were experimentally verified in the fundamental symmetric and asymmetric Lamb waves on an aluminum plate generated by a long‐pulse Nd:YAG laser. Applications to anisotropy and thickness measurements are discussed.
TL;DR: In this article, a single-mode polymer waveguide modulator which can be formed on any surface regardless of its conductivity and refractive index is presented. But the phase-matching condition for optical power transfer is achieved through current-induced index modulation.
Abstract: We report herein the first single‐mode polymer waveguide modulator which can be formed on any surface regardless of its conductivity and refractive index These include semiconductor, conductor, and insulator surfaces The tunability of the refractive index of the polymer film allows us to shift the guiding layer from a stepped index profile to a graded index profile The phase‐matching condition for optical power transfer is achieved through current‐induced index modulation Thirty‐six dB extinction ratio, which includes 3 dB absorption loss and 33 dB phase‐matched cross coupling, was observed with a current injection density of ∼18 μA/μm2 Unlike the conventional symmetrical dual channel coupler, the disparity of the collinear waveguide pair provides us with a much larger dynamic range of waveguide dimension suitable for generating the required phase‐matching condition and thus easing the requirement of waveguide fabrication
Patent•
07 Jun 1991TL;DR: In this paper, a control unit varies the wavelength of the optical signal by varying the temperature of a semiconductor laser constituting the optical source, so that the loss-distance characteristics for a plurality of different wavelengths are determined and can be displayed to show any wavelength dependent loss of an optical fiber path.
Abstract: In an optical time domain reflectometer (OTDR), an optical signal is coupled to an optical fiber path to be tested, and back-scattered and reflected light from the optical fiber path is detected and used to determine loss-distance characteristics of the path. A control unit varies the wavelength of the optical signal by varying the temperature of a semiconductor laser constituting the optical source, so that the loss-distance characteristics for a plurality of different wavelengths are determined and can be displayed to show any wavelength dependent loss of the optical fiber path, which loss may be due to modal interference associated with closely spaced discontinuities in the path.
TL;DR: In this paper, an optical time-domain reflectometer (OTDR) with −136 dB minimum detectable reflectivity and 14 μm spatial resolution was developed based on low coherence interference.
Abstract: An optical time‐domain reflectometer (OTDR) with −136 dB minimum detectable reflectivity and 14 μm spatial resolution is developed based on low coherence interference. The high sensitivity was accomplished by using a high‐power superluminescent diode module with a 1.5 mW fiber output and a new system configuration, both for effectively operating the balanced heterodyne detection. The reflectivity of −136 dB is only 6 dB above the shot noise limit. The first observation of 1.3 μm wavelength Rayleigh backscattering in single‐mode fibers was successfully made by the OTDR with a 17 dB dynamic range and 14 μm spatial resolution.
TL;DR: In this paper, the operating characteristics of a novel grating surface emitting laser structure containing a buried second-order grating have been studied both experimentally and theoretically, and the results showed that single mode operation (>30 dB side mode suppression) and single-lobed far fields with negligible sidelobes are observed up to more than 5*I/sub th/ with spectral linewidths as narrow as 1 MHz.
Abstract: The operating characteristics of a novel grating surface emitting laser structure containing a buried second-order grating have been studied both experimentally and theoretically. This device consists of a pumped distributed feedback (DFB) section that is terminated at each end by unpumped distributed Bragg reflector (DBR) sections. A single continuous second-order grating layer and waveguide layer extend throughout the active and passive sections so that there is essentially no fabricated optical discontinuity at the interface between the active and passive end sections. Single mode operation (>30 dB side mode suppression) and single-lobed far fields with negligible sidelobes are observed up to more than 5*I/sub th/ with spectral linewidths as narrow as 1 MHz. >
TL;DR: In this article, a novel type of optical beam scanning device based on the same principle as a phased array radar has been made and demonstrated, which consisted of a uniformly illuminated array of ten closely spaced, single mode GaAs/AlGaAs electrooptic waveguides, each of which was individually addressed to give more than 2π radians of optical phase control.
Abstract: A novel type of optical beam scanning device based on the same principle as a phased array radar has been made and demonstrated. This phased array optical scanning device consisted of a uniformly illuminated array of ten closely spaced, single mode GaAs/AlGaAs electrooptic waveguides, each of which was individually addressed to give more than 2π radians of optical phase control. This gave a line of ten point sources of light on a 3 μm pitch at the output face of the array. By independently phase shifting these light sources the output wavefront was controlled to scan a 2° wide beam through 20° in the far field.
Patent•
31 May 1991TL;DR: In this article, a wavelength selective structure is coupled to an adiabatic Y-coupler via a multimode section which supports both symmetric and antisymmetric modes.
Abstract: A wavelength selective structure is coupled to an adiabatic Y-coupler via a multimode section which supports both symmetric and antisymmetric modes. One single mode branch of the coupler converts guided light to a symmetric mode, whereas the other single mode branch converts guided light to an anti-symmetric mode. The structure, which includes a pair of single mode waveguide arms coupled to the common section and a reflection device (such as a grating or ROR) located in each arm, converts reflected light from a symmetric mode to an anti-symmetric mode and conversely. Applications described include a channel dropping filter and channel balancing apparatus for WDM systems, and a dispersion compensator for fiber optic systems.
TL;DR: In this article, a high-isolation polarization-independent optical circulator is reported, where a birefringent plate is added to each port to achieve high isolation.
Abstract: A high-isolation polarization-independent optical circulator is reported. The goal is to provide a simple structure that sharply diminishes the degradation on the isolation caused by imperfection of polarization separation in the polarizing beam splitters. The circulator structure is almost the same as that of a conventional circulator except that a birefringent plate is added to each port to achieve high isolation. The effectiveness of the added birefringent plate has been confirmed by calculation and experiment. Insertion loss and isolation of the fabricated circulator coupled with single-mode fibers have been measured to be 29.9 dB, respectively, for 1.299 mu m wavelength light. A loss ratio over 28.9 dB has been realized. >