Showing papers on "Single-mode optical fiber published in 1983"
TL;DR: In this article, the basic birefringences that couple the two modes and change the polarization state along the fiber are reviewed, and three cases of uniform, phase-matched, and random coupling are considered.
Abstract: The polarization state of light in single-mode fibers is very sensitive to any perturbation which is not symmetric about the fiber axis. While this is a source of noise, drift, or signal fading in some applications, it can also be exploited in novel guided-wave devices. The basic birefringences that couple the two modes and change the polarization state along the fiber are reviewed. The three cases of uniform, phase-matched, and random coupling are considered. Polarization preservation in both low- and high-birefringence fibers is achieved by reducing this coupling. In addition to polarization-state changes, bireftingent fibers can quickly reduce the polarization degree of nonmonochromatic light if both modes are excited, a characteristic that greatly simplifies evaluation of the degree of polarization preservation in these fibers. Current evaluations of the birefringence and the polarization-holding ability of state-of-the-art fibers are discussed, and it is concluded that fibers with good polarization-holding properties are becoming available.
492 citations
TL;DR: The narrowing of pulses to widths as small as 0.26 psec by various lengths, short relative to the soliton period, of single-mode, low-loss optical fiber is reported to be in at least semiquantitative agreement with prediction based on the nonlinear Schrödinger equation.
Abstract: We report the narrowing of pulses, initially 7 psec FWHM, to widths as small as 0.26 psec by various lengths, short relative to the soliton period, of single-mode, low-loss optical fiber. Since the ~1.5-μm wavelength lies in the region of negative group-velocity dispersion (∂νg/∂λ 10) soliton number. We show these results to be in at least semiquantitative agreement with prediction based on the nonlinear Schrodinger equation.
382 citations
TL;DR: In this paper, the fundamental mode spot size for broadband dispersion-compensated fibres was investigated and the relationship between dispersion and spot size was shown to be a limiting factor.
Abstract: Constraints exist for the fundamental-mode spot size for broadband dispersion-compensated fibres because of the relationship between dispersion and spot size. Dispersion compensation between 1.3 and 1.55 µm is still possible with the usual spot radius of about 5 µm at λ = 1.3 µm, while dispersion compensation between 1.3 and 1.8 µm would require a spot radius of less than 4 µm.
211 citations
TL;DR: In this article, the use of broad-band sources, polarized and unpolarized, in fiber gyroscopes with linearly birefringent fibers was studied theoretically.
Abstract: The use of broad-band sources, polarized and unpolarized, in fiber gyroscopes with linearly birefringent fibers, is studied theoretically. Polarization-mode coupling in the fiber is modeled using one-mode coupling center. Gyroscope output equations are obtained which are useful in interpreting an origin of fiber noise in the limiting cases of low and high fiber birefringence. Interference effects in the output are shown to be related to mode coupling at particular locations in the fiber. The extent of these locations is governed by a depolarization length for which numerical estimates are given.
181 citations
TL;DR: By use of the stimulated Raman process, optical solitons can be amplified and reshaped while they propagate through a glass fiber to allow the separation between two repeaters (amplifiers) to be decided by the fiber loss rather than by the Fiber dispersion.
Abstract: By use of the stimulated Raman process, optical solitons can be amplified and reshaped while they propagate through a glass fiber. When an appropriate level is chosen for the pump power (10–100 mW for 10-psec solitons), the solitons can be reshaped adiabatically. The method allows the separation between two repeaters (amplifiers) to be decided by the fiber loss rather than by the fiber dispersion.
146 citations
TL;DR: In this article, a fiber polarizer with high modal birefringence (4.7 \times 10−4 ) was proposed to split the two polarizations of the fundamental mode and an ellipitcal depressed-index cladding to provide a steep wavelength-dependent tunneling loss to the fast axis mode.
Abstract: We report an oPtical fiber which guides only one polarization. This fiber polarizer utilizes high modal birefringence ( 4.7 \times 10^{-4} ) to split the two polarizations of the fundamental mode and an ellipitcal depressed-index cladding to provide a steep wavelength-dependent tunneling loss to the fast axis mode. The stress-induced birefringence is created by an elliptical SiO 2 -B 2 O 2 inner cladding. A 4.7-m length of polarizer fiber exhibits an extinction ratio of 34 dB at a wavelength of 633 nm, with polarizing behavior over a bandwidth of 50 nm. Insertion loss of less than 1 dB has been observed for the guided linear-polarization mode. The polarizing band may be shifted from 620 to 525 nm by bending the fiber to a radius of 0.67 cm. Such fiber polarizers should find a variety of applications in fiber sensors, attenuators, isolators, wavelength filters, and tuners.
143 citations
TL;DR: In this article, the authors discuss the possibility for semiconductor laser amplifiers to be used in a single-mode fiber communication system, and derive the power budget improvement due to the insertion of a laser amplifier in a digital optical communication system.
Abstract: The recent advent of very low loss single mode optical fibers (< 0.2 dB/km at the 1.55μπι wavelength) opens the possibility for very long distance, high information bandwidth (^1 Gbit/s) communication systems, as transoceanic cable links or trunk networks. With such fibers, especially when chromatic dispersion is negligible, the range is only limited by attenuation, so there would be no need for complete signal regeneration (pulse shaping, timing, etc...). In these conditions, direct light amplifiers would be very attractive as \"on-line\" amplifiers as an alternative to sophisticated optoelectronic repeaters; they could also be used in a receiver as low noise preamplifiers, in combination with a pinphotodiode, especially at the 1.3 ... 1.55 μη wavelength, where avalanche photodiodes (APD) are more \"noisy\" than silicon APDs. It is our purpose to discuss the possibility for semiconductor laser amplifiers to be used in a single mode fiber communication system. We shall first derive the power budget improvement due to the insertion of a laser amplifier in a digital optical communication system. A review of semiconductor laser amplifiers (SCLA) characteristics of the traveling-wave type (TW), Fabry-Perot type (FP) and injection locked laser type (ILL) will then be presented, with emphasis on recent experimental results. Finally, possible applications of these devices in single mode fiber communication systems will be discussed. 2 Noise characteristics of a laser amplifier in an optical communication system
138 citations
TL;DR: In this paper, the theory of backscattering in single-mode optical fibers is described through use of a correlation function for the refractive index fluctuation in the fiber and a simple formula for the backscattered power is derived using two correlation functions for the Booker-Gordon and Gaussian models.
Abstract: The theory of backscattering in single-mode optical fibers is described through use of a correlation function for the refractive-index fluctuation in the fiber. A simple formula for the backscattered power is derived using two correlation functions for the Booker–Gordon and Gaussian models. The zeroth-order approximation of the formula, in which the correlation length is much smaller than the spot size of the waveguide mode, coincides with Brinkmeyer’s model. The backscattered power at the input end of single-mode fiber is compared with that for multimode fiber. It is also shown that the backscattered power level at the input end is lower by approximately 55 dB than the input power level.
134 citations
TL;DR: Pulse restoration occurs despite initial spectral broadening from self-phase modulation and temporal compression as a result of negative group-velocity dispersion acting on the chirped pulse.
Abstract: Restoration in both shape and spectrum of a (train of) 6.4-psec optical pulses has been observed at the soliton period in a single-mode fiber. The source was an F2+ color-center laser at 1.55 μm, and the fiber was 1.3 km long, which was one soliton period for this pulse width and wavelength. As predicted by the nonlinear Schrodinger equation, pulse restoration occurs despite initial spectral broadening from self-phase modulation and temporal compression as a result of negative group-velocity dispersion acting on the chirped pulse.
123 citations
Book•
01 Jan 1983
TL;DR: A basic, unified reference, rather than a description of the current experimental activity, presenting the scientific and engineering principles of single-mode optical fibers.
Abstract: A basic, unified reference, rather than a description of the current experimental activity, presenting the scientific and engineering principles of single-mode optical fibers. It does, however, update discussions to reflect developments since the 1983 first edition, particularly those spurred by the
111 citations
TL;DR: In this article, a simple fibry Fabry-Perot sensor is described in which the uncoated cleaved ends of a length of single mode fibre are employed as the mirror surfaces to produce high visibility cosine squared fringes in the back reflected light.
TL;DR: The dependence of the multiplexer behavior on all relevant parameters is investigated and found to satisfy predicted results.
Abstract: Theoretical and experimental studies of wavelength-division multiplexing in a single-mode fiber optic coupler fabricated by mechanical polishing are reported. The variable spacing geometry of the device allows fine tuning of the center wavelength of operation. Wavelength selectivities ranging from 200 to 35 nm have been experimentally demonstrated, with cross talk ranging from 50 to 10 dB. Selectivity control is simply achieved by proper choice of the interaction length of the coupler. The dependence of the multiplexer behavior on all relevant parameters is investigated and found to satisfy predicted results.
IBM1
TL;DR: The experimental results agree well with the predicted intensity dependence of the reshaping action of nonlinear birefringence during passage through a 150-cm-long, single-mode optical fiber and a crossed polarizer.
Abstract: We report the observation of strong reshaping of 3-psec dye-laser pulses by nonlinear birefringence during passage through a 150-cm-long, single-mode optical fiber and a crossed polarizer. For lower-intensity input pulses to the fiber, the transmitted pulses were observed to be proportional to the cube of the input pulses. With increased intensity, more-complicated pulse shapes were obtained. Our experimental results agree well with the predicted intensity dependence of the reshaping action.
TL;DR: In this article, the beam-propagation method was used to calculate both the pure bending loss and the transition loss of bent single-mode optical waveguides and fibers, which allowed the authors to establish the accuracy of several commonly used theories of bending loss.
Abstract: We demonstrate that the beam-propagation method can be used to calculate accurately both the pure bending loss and the transition loss of bent single-mode optical waveguides and fibers. Our results allow us to establish the accuracy of several commonly used theories of bending loss and to investigate the degree to which theories of step-index monomode fiber losses can be used to predict the losses of graded-index monomode fibers.
TL;DR: In this article, a new type of single-mode four-port electro-optic switch is investigated based on the electrically controlled two-mode interference in the intersection region of two crossing singlemode channel waveguides.
Abstract: A new type of single-mode four-port electro-optic switch is investigated. The operation principle is based on the electrically controlled two-mode interference in the intersection region of two crossing single-mode channel waveguides. The switch is analysed numerically by the beam-propagation method, and is realised experimentally by using Ti:LiNbO3 channel waveguides.
TL;DR: In this paper, the decay rates of the longitudinal laser modes are found to be inversely proportional to their corresponding steady-state mode amplitudes, and the authors discussed the feasibility of constructing approximate, analytical solutions of the rate equations for an injection laser with several longitudinal modes.
Abstract: We discuss the feasibility of constructing approximate, analytical solutions of the rate equations for an injection laser with several longitudinal modes. By adjusting a few empirical parameters it is possible to reproduce the principal features of the exact numerical solutions for the electron and photon densities and to provide explicit expressions for the frequency and time decay rates of the relaxation oscillations. The solutions show that the relative powers of the modes change continually during the transient period. Initially, many longitudinal modes begin to oscillate with nearly equal amplitudes which decay at different rates until they settle down to form a Lorentzian, steady-state distribution. In short lasers ( m) this behavior permits a single mode to establish itself rapidly, leading to single wavelength operation. The decay rates of the longitudinal laser modes are found to be inversely proportional to their corresponding steady-state mode amplitudes.
TL;DR: In this article, four different techniques for measuring the spot size of a single-mode fiber are compared for accuracy and ease of use, based upon imaging of the fiber near fields onto an infrared vidicon, measuring splice loss sensitivity to transverse offset, approximating the fiber far-field radiation pattern as a Gaussian beam, and using the inverse Hankel transform of the far field radiation pattern.
Abstract: Four techniques for measuring the spot size of a single-mode fiber are compared for accuracy and ease of use. The techniques are based upon imaging of the fiber near fields onto an infrared vidicon, measuring splice loss sensitivity to transverse offset, approximating the fiber far-field radiation pattern as a Gaussian beam, and using the inverse Hankel transform of the far-field radiation pattern. All four methods agree quite well (within 2 percent) considering that the Gaussian fields upon which spot size is based are only an approximation of the actual fields in the fiber. The far-field Gaussian beam technique was found to be the easiest and fastest of the four techniques.
TL;DR: In this paper, the authors demonstrate that the propagating beam method can be employed to determine the behavior of optical fiber solitons in the presence of optical loss, third order dispersion and fifth order nonlinearity.
TL;DR: In this paper, a single-mode, single-polarization fiber design that can be realized by stress-induced birefringence was proposed, and the leakage rate was calculated by a perturbation method, which accounts for degeneracy between a bound mode and a packet of radiation modes.
Abstract: Optical fibers composed of highly birefringent material are studied. One of the two fundamental modes can be made leaky when the birefringence is sufficiently large. This suggests a novel single-mode, single-polarization fiber design that can be realized by stress-induced birefringence. The leakage rate is calculated by a perturbation method, which accounts for degeneracy between a bound mode and a packet of radiation modes.
TL;DR: In this paper, a two-section GaInAsP/InP laser was shown to operate in a single longitudinal mode under high-speed pulsed current modulation, where the length of the emitted monomode light pulses is less than 500 ps.
Abstract: Monolithic two‐section GaInAsP/InP lasers are shown to operate in a single longitudinal mode under high‐speed pulsed current modulation. The length of the emitted monomode light pulses is less than 500 ps. The suppression of secondary modes is described in a rate equation model that is generally useful for a variety of coupled‐cavity configurations. It is found that 10% increase in cavity loss for the unwanted modes is sufficient to provide 17 dB suppression.
TL;DR: In this paper, a fiber-optic frequency shifter was constructed using a birefringent singlemode fiber positioned asymmetrically within two acoustic resonators driven 90° out of phase.
Abstract: A fibre-optic frequency shifter has been constructed using a birefringent single-mode fibre positioned asymmetrically within two acoustic resonators driven 90° out of phase. The incident wave in one polarisation state is coupled to a frequency-shifted wave in the orthogonal state. Sideband suppression of better than 20 dB is achieved.
TL;DR: In this article, the reduction of the degree of polarization of broadband light due to propagation in ordinary single-mode fiber is examined theoretically and experimentally, and a model for one discrete mode-coupling center and extending it qualitatively to include multiple centers is developed.
Abstract: The reduction of the degree of polarization of broad-band light due to propagation in ordinary single-mode fiber is examined theoretically and experimentally. Previous work is extended to account for polarization-mode coupling along the fiber by developing a model for one discrete mode-coupling center and extending it qualitatively to include multiple centers. The existence of nonzero degree of polarization in long lengths of fiber is shown to be due to mode coupling at particular positions along the fiber and the degree of polarization is shown to be related to the degree of coherence associated with the mode-coupling site. The experimental results generally support the model developed.
TL;DR: By using cw laser diodes operating at 1.26 and 1.34 microm, the cross talk caused by stimulated Raman scattering in a 21-km single-mode fiber was measured to be -25.2 dB at a pump-power level of 1.0 mW, in good agreement with previously reported values measured with high-power pulsed lasers.
Abstract: By using cw laser diodes operating at 1.26 and 1.34 μm, the cross talk caused by stimulated Raman scattering in a 21-km single-mode fiber was measured to be −25.2 dB at a pump-power level of 1.0 mW. The Raman-gain coefficient was calculated to be 0.57 × 10−11 cm/W, which is in good agreement with previously reported values measured with high-power pulsed lasers.
TL;DR: In this paper, a fiber interferometer is presented which utilizes a high-finesse all-single-mode-fiber ring resonator with a measured sensitivity to periodic phase shifts induced in the fiber ring.
Abstract: A new type of fiber interferometer is presented which utilizes a high-finesse all-single-mode-fiber ring resonator. The measured sensitivity to periodic phase shifts induced in the fiber ring is 1.0 \times 10^{-6} rad/ \sqrt{Hz} or better over the 100-Hz-10-kHz frequency range with maximum sensitivity of 1.9 \times 10^{-7} rad/ \sqrt{Hz} at 10 kHz. This sensitivity, while high, is not shot-noise limited and appears to be determined by the spectral bandwidth of the single-frequency laser source.
Patent•
16 Jun 1983TL;DR: In this paper, a single-cavity laser with a single longitudinal mode output is maintained even during high speed modulation in which the current or ambient conditions vary, by generating a control signal to the laser to produce the output.
Abstract: Control circuits stabilize and maintain coupled-cavity lasers in a single longitudinal mode. The laser is electrically connected and mutually and optically coupled to a control means responsive to a light output signal from the laser for controlling the laser by generating a control signal to the laser to produce single longitudinal mode output. The single mode output is maintained even during high speed modulation in which the current or ambient conditions vary.
TL;DR: The transmission performance of trapezoidal-index profile single-mode fibers that can operate with zero dispersion in the 1.5-microm region has been investigated and it was found that as the aspect ratio decreases the optimum core radius of the fiber gradually increases.
Abstract: The transmission performance of trapezoidal-index profile single-mode fibers that can operate with zero dispersion in the 1.5-microm region has been investigated. The exact numerical calculations of propagation characteristics for these lightguides established a variety of relationships in terms of the parameters of a trapezoidal-index profile. One of the profile parameters that defines the shape of a trapezoid is the aspect ratio S, which ranges between 0 and 1. It was found that as the aspect ratio decreases from 1.0 to 0.3 the optimum core radius of the fiber gradually increases. But when S is <0.3, it approaches a constant equal to the value of the triangular-index profile (S = 0).
TL;DR: Results show that reducing the buffer diameter and controlling the fiber deformation inside the jacket are effective in suppressing excess loss at low temperature.
Abstract: This paper describes excess loss of single-mode jacketed optical fibers at low temperature. A structural model is proposed for the jacketed fiber in order to investigate the relationship between the structure and excess loss. This model clarifies the excess loss increase mechanism that any initial irregularity existing in the jacketed fiber increases due to shrinkage of the jacket and causes excess loss. These results show that reducing the buffer diameter and controlling the fiber deformation inside the jacket are effective in suppressing excess loss at low temperature.
TL;DR: In this article, a broad-band ultrasonic sensor based on induced optical phase shifts in single-mode fibers is demonstrated over a frequency regime of 0.5-50 MHz, and a recently developed theory used to predict the magnitudes of acoustically induced strains in optical fibers is verified.
Abstract: A broad-band ultrasonic sensor based on induced optical phase shifts in single-mode fibers is demonstrated over a frequency regime of 0.5-50 MHz. In addition, a recently developed theory used to predict the magnitudes of acoustically induced strains in optical fibers is verified.
TL;DR: In this article, the theory for understanding fibres composed of highly birefringent material is presented and one of the two possible polarisation states of the fundamental mode can be made leaky, suggesting a novel single-mode single-polarisation fibre design.
Abstract: The theory for understanding fibres composed of ‘highly’ birefringent material is presented. One of the two possible polarisation states of the fundamental mode can be made leaky, suggesting a novel single-mode single-polarisation fibre design. No leakage occurs in planar waveguides constructed similarly from the identical material.
Patent•
08 Aug 1983TL;DR: In this paper, the authors measured the chromatic dispersion of an optical fiber such as a 10 to 50 km length of single mode fiber by launching into the fiber the outputs of at least three commonly modulated semiconductor lasers having output wavelengths close to a region of minimum dispersion.
Abstract: The chromatic dispersion of an optical fiber such as a 10 to 50 km length of single mode fiber is measured by launching into the fiber the outputs of at least three commonly modulated semiconductor lasers having output wavelengths close to a region of minimum chromatic dispersion of the fiber. At a remote end of the fiber the relative phases of the signals from the three lasers are determined and a chromatic dispersion profile of the fiber is derived from the measured relative phases and the output wavelenghts of the lasers by assuming a parabolic relationship between signal propagation times and wavelength. The profile can be determined by defferentiating a parabolic function fitted to the three date points derived using said three lasers or by directly generating a linear relationship between chromatic dispersion and wavelength on the basis of two values of chromatic dispersion derived from these three data points.