Showing papers on "Dispersion-shifted fiber published in 1981"
TL;DR: In this article, the backscattered light amplitude is measured from one end of a fiber as a function of optical frequency by tuning a HeNe laser over its linewidth.
Abstract: The backscattered light amplitude is measured from one end of a fiber as a function of optical frequency by tuning a HeNe laser over its linewidth. Fourier transform by a low‐frequency electronic spectrum analyzer then reveals the spatial distribution of scattering and of the fiber losses.
504 citations
01 Sep 1981
TL;DR: In this article, a transmission rate of ≃1 Tbits/sec (≃0.1 T bits/s) per 30 km can be achieved using envelope solitons with peak power of approximately 10 W in a monomode optical fiber, respectively.
Abstract: A transmission rate of ≃1 Tbits/sec (≃0.1 Tbits/s) per 30 km can be achieved using envelope solitons with peak power of ≃10 W (≃10 mW) in a monomode optical fiber, respectively. Unlike the linear pulse in which the bit rate is limited by the group dispersion, the bit rate of soliton transmission is limited by the fiber loss and the input power. Conditions for achieving optimum transmission rate using solitons are theoretically obtained including the effects of fiber loss and second order group dispersion.
326 citations
TL;DR: It is shown that whereas a conventionally twisted fiber possesses considerable optical rotation, a fiber which has a permanent twist imparted by spinning the preform during fiber drawing exhibits almost no polarization anisotropy, making it possible to virtually eliminate the commonly observed fiber linear birefringence.
Abstract: A theoretical and experimental analysis of the polarization properties of twisted single-mode fibers is presented. It is shown that whereas a conventionally twisted fiber possesses considerable optical rotation, a fiber which has a permanent twist imparted by spinning the preform during fiber drawing exhibits almost no polarization anisotropy. It is thus possible to virtually eliminate the commonly observed fiber linear birefringence. As a consequence, fibers made in this way are ideally suited for use in the Faraday-effect current transducer. It is further shown that a permanent twist of a few turns/meter effectively eliminates polarization mode-dispersion. The technique therefore appears attractive for enhancing the bandwidth of very long unrepeatered telecommunication links.
283 citations
TL;DR: In this paper, the predictions of the nonlinear Schrodinger equation have been tested by passing 5.5psec optical pulses through a 70m single-mode optical fiber, and dramatic reshaping of the input pulses into flat-topped, frequency-broadened, and positively chirped 20psec output pulses with self-steepened fall times of less than 2 psec was observed.
Abstract: The predictions of the nonlinear Schrodinger equation have been tested by passing 5.5-psec optical pulses through a 70-m single-mode optical fiber. With use of a precise cross correlation technique based on pulse compressions, dramatic reshaping of the input pulses into flat-topped, frequency-broadened, and positively chirped 20-psec output pulses with self-steepened fall times of less than 2 psec was observed. The observations are in good agreement with theory.
265 citations
TL;DR: Single-mode fiber couplers produced as fused biconical-taper structures are reported on that exhibit low loss, arbitrary branching ratio, polarization independence, and broadband operation in wavelength.
Abstract: Single-mode fiber couplers produced as fused biconical-taper structures are reported on. The devices exhibit low loss (0.5 dB), arbitrary branching ratio, polarization independence, and broadband operation in wavelength.
231 citations
TL;DR: A theoretical model is developed, and relevant fiber parameters are determined through intercomparison with experiment, both the magnitude of the photoinduced index change and its dependence on the writing power coupled into the fiber are determined.
Abstract: The fabrication of narrowband highly reflecting filters in single-mode step-index fibers was reported recently by Hill et al. [
Appl. Phys. Lett.32,
647 (
1978)]. The underlying effect on which these filters are based is a photoinduced refractive-index change in the GeO2 used as a core dopant SiO2 fibers. A study is reported aimed at the characterization of such optical fiber filters. A theoretical model is developed, and relevant fiber parameters are determined through intercomparison with experiment. In this way, both the magnitude of the photoinduced index change and its dependence on the writing power coupled into the fiber are determined.
221 citations
TL;DR: In this article, the authors measured the dispersion of a single-mode optical fiber only 1 m long by a newly proposed interferometric method, where interference fringes are produced by two laser beams, one transmitting through the fiber and the other through air.
Abstract: Chromatic dispersion of a single-mode optical fiber only 1 m long is measured by a newly proposed interferometric method. Interference fringes are produced by two laser beams, one transmitting through the fiber and the other through air. Path length shifts in an interferometer for attaining the visibility maximum are measured by varying optical source wavelengths between 818 and 904 nm. Group delay time differences around 1 ps are measured. The measured results are in good agreement with those measured by the conventional pulse method for the identical 1.3 km long fiber.
218 citations
TL;DR: In this paper, the effects of twist in an elliptical core fiber gave rise to a polarization whose major axis points in an intrinsic direction with an azimuthal angle, where φ t is the torsion per unit length and z is the fiber length.
Abstract: Birefringence and polarization dispersion caused by: 1) elliptical core, 2) twist, 3) pure bending, 4) transverse pressure, and 5) axial tension are studied by treating these deformations as perturbations to step-index single-mode fiber with a round core. These effects ate formulated in terms of fiber structure and perturbation parameters and are compared comprehensively. Birefringence depends strongly on factors 1)-4), while polarization dispersion depends on factors 1), 3), and 4). Polarization performance of twisted elliptical core fibers was also studied. Twist in an elliptical core fiber gives rise to a polarization whose major axis points in an intrinsic direction with an azimuthal angle \phi_{t}z , where φ t is the torsion per unit length and z is the fiber length.
173 citations
TL;DR: In this paper, the simulation of signal propagation in a single-mode fiber is considered by using the analogous Fresnel diffraction experiment, where the transfer of information in fibers with a large dispersion of the first order is accomplished by a temporal analog of the self-imaging effect.
Abstract: The transfer of information in fibers with a large dispersion of the first order is accomplished by a temporal analog of the self-imaging effect. The simulation of signal propagation in a single-mode fiber is considered by using the analogous Fresnel diffraction experiment.
129 citations
TL;DR: In this paper, the authors describe the theoretical and experimental study of an optical time domain reflectometry (OTDR) in a single-mode fiber and the maximum measurable distance by the OTDR is theoretically studied.
Abstract: This paper describes the theoretical and experimental study of an optical time domain reflectometry (OTDR) in a single-mode fiber. The maximum measurable distance by the OTDR is theoretically studied. In the experiment, the cylindrical lens attached to the laser diode, the low-loss and low-crosstalk directional coupler, and the digital averaging technique combined enabled us to measure a break in a single-mode fiber up to 17 km in length. This paper also describes the application of the OTDR to loss measurement of a single-mode fiber.
TL;DR: A new technique that utilizes birefringence for phase matching of stimulated parametric emission in a single-mode optical fiber and the frequency shift between the generated frequencies and the pump frequency can be controlled over a wide range by the magnitude of bireFringence built into the fiber.
Abstract: We describe a new technique that utilizes birefringence for phase matching of stimulated parametric emission in a single-mode optical fiber. The frequency shift between the generated frequencies and the pump frequency can be controlled over a wide range (approximately 1000 cm(-1)) by the magnitude of birefringence built into the fiber.
TL;DR: The rotational sensitivity of the Fiber resonator gyro is derived and shown to be approximately equal to that of the fiber interferometer gyro for typical fiber and source parameters.
Abstract: The rotational sensitivity of the fiber resonator gyro is derived and shown to be approximately equal to that of the fiber interferometer gyro for typical fiber and source parameters. The fiber resonator, like the fiber interferometer, is susceptible to errors due to thermally induced nonreciprocity; however, by reducing splice and coupler losses, it should be possible to reduce these errors well below those in the fiber interferometer.
TL;DR: In this article, three basic types of single-polarization single-mode (SPSM) optical fibers have been developed: elliptical-core fiber, stress-induced birefringent fiber, and side-pit fiber.
Abstract: Strictly speaking, an ordinary axially symmetrical single-mode fiber is a "two-mode" fiber because two orthogonally polarized HE 11 modes can be propagated in it. This fact results in the instability of the polarization state of the propagated mode when geometrical perturbation exists in the fiber, and also the so-called polarization mode dispersion. These are harmful in some applications of single-mode fibers to communication and measurement. To prevent these adverse effects, single-polarization single-mode (SPSM) optical fibers have been developed. Three basic types of the SPSM fiber are elliptical-core fiber, stress-induced birefringent fiber, and side-pit fiber. This paper describes the principles of these three types, performance obtained experimentally, theoretical approaches, and measurement techniques related to the SPSM fibers. Finally, relevant technical tasks in the future are mentioned.
TL;DR: The conditions on modal amplitudes and modal dispersion necessary for soliton existence are derived in a set of nonlinear coupled equations derived in the frame of coupled-mode theory.
Abstract: Soliton propagation in a multimode optical fiber in the presence of an intensity-dependent refractive index is investigated by means of a set of nonlinear coupled equations derived in the frame of coupled-mode theory. In particular, the conditions on modal amplitudes and modal dispersion necessary for soliton existence are derived.
TL;DR: A fiber-optic magnetic-field sensor is constructed by bonding a single-mode fiber to a nickel cylinder by means of the magnetostrictive effect, permitting detection of fields as small as 4.4 x 10(-6) Oe/m of fiber.
Abstract: A fiber-optic magnetic-field sensor is constructed by bonding a single-mode fiber to a nickel cylinder The magnetic field, by means of the magnetostrictive effect, alters the state of polarization of light in the fiber A sensitivity of 176 × 10−2 rad/m Oe is demonstrated, permitting detection of fields as small as 44 × 10−6 Oe/m of fiber
TL;DR: The local parameters of linear, circular, and elliptical birefringence of backscattered light along a single-mode fiber are analyzed, and the twist-bending-induced ellipticalbireferingence in an extremely low bireFringent single- mode fiber is measured using the backscattering method.
Abstract: The local parameters of linear, circular, and elliptical birefringence of backscattered light along a single-mode fiber are analyzed, and the twist–bending-induced elliptical birefringence in an extremely low birefringent single-mode fiber is measured using the backscattering method. The experimental results are in good agreement with the theoretical calculations. For a 130-μm-diameter fiber, twisted by 133°/m and wound around a drum of 15-cm radius, the induced elliptical birefringence is|Ω| = 18°/m at λ = 904 nm.
TL;DR: The effects of group-velocity dispersion, thermal stability of polarization, and fiber birefringence are investigated, and it is concluded that resolution times shorter than 1 psec are possible in principle.
Abstract: Optical Kerr modulation of >100% is demonstrated in long birefringent optical fibers using low laser powers of ~1 W. We have experimentally investigated the effects of group-velocity dispersion, thermal stability of polarization, and fiber birefringence. Use of fiber Kerr modulation as a fast optical shutter is studied, and it is concluded that resolution times shorter than 1 psec are possible in principle.
TL;DR: In this article, the theoretical and practical limits of the maximum transmission bandwidth in single-mode fibers were investigated from both the theoretical as well as the practical point of view, and a comparison between the chromatic dispersion and the polarization mode dispersion was made.
Abstract: We consider the question of the maximum transmission bandwidth in single-mode fibers from the theoretical as well as practical point of view. First, we show that there is an optimal input pulsewidth which gives minimum output pulsewidth and, therefore, determines the theoretical maximum transmission bandwidth. Both the first- and second-order dispersion terms are taken into account in calculating the optimal input pulsewidth, the optimal (minimum) output pulsewidth, and the corresponding maximum information rate for given fiber and source parameters. Next, we consider increasing the maximum transmission bandwidth by shifting the fiber's dispersion minimum to the desired wavelength, utilizing the doping and waveguide dispersion shifts. For long concatenated single-mode fibers, we also consider dispersion minimization using optical pulse equalization by purposely connecting fibers with positive and negative dispersion characteristics in series. Lastly, we consider polarization mode dispersion due to birefringence associated with fiber core ellipticity and asymmetrical stress. Based on these dispersion considerations, practical numerical examples are given, and a comparison between the chromatic dispersion and the polarization mode dispersion is made. The practical limit to the maximum transmission bandwidth in single-mode fibers is discussed.
TL;DR: In this paper, the requirements of such a system are reviewed and interpreted in terms of individual components design, and it is concluded from these very promising results that a heterodyne-type communication system using single-mode fibers at 1.6 μm may offer repeater spacings of over 200 km in the near future.
Abstract: The unique performances attached to the heterodyne (or coherent) optical detection process can be fully exploited with single-mode fiber transmission. Strong improvement over direct detection is expected in terms of bit error rate (BER) or in terms of repeater spacing, especially for 1.6 μm operation. The requirements of such a system are reviewed and interpreted in terms of individual components design. The emission frequency stability of laser diodes, the ability of single-mode fiber cables to maintain polarization, and the availability of direct light amplifiers are found to be the most critical points, and recent theoretical and experimental results are reported. It is concluded from these very promising results that a heterodyne-type communication system using single-mode fibers at 1.6 μm may offer repeater spacings of over 200 km in the near future.
TL;DR: The effect of optical signal intensity at the wavelength of system operation on the recovery of the radiation-induced attenuation in optical fiber waveguides following exposure to a 3700-rad dose of ionizing radiation has been investigated.
Abstract: The effect of optical signal intensity at the wavelength of system operation (0.85 μm) on the recovery of the radiation-induced attenuation in optical fiber waveguides following exposure to a 3700-rad dose of ionizing radiation has been investigated. Photobleaching has been observed in both pure and doped silica core fibers, although the effect is more pronounced in the former.
Patent•
17 Aug 1981TL;DR: In this article, a sensor is provided for sensing or detecting the presence of an environmental field condition such as acceleration, temperature change, magnetic or acoustic fields by interference between two mutually orthogonal polarized eigenmodes in a single monomode optical fiber which may be disposed either linearly or wound on a mandrel made of compliant material for sensing an acoustic field, or made of magnetostrictive material for detecting a magnetic field.
Abstract: A sensor is provided for sensing or detecting the presence of an environmental field condition such as acceleration, temperature change, magnetic or acoustic fields. The field is sensed by interference between two mutually orthogonal polarized eigenmodes in a single monomode optical fiber which may be disposed either linearly or wound on a mandrel made of compliant material for sensing an acoustic field, or made of magnetostrictive material for sensing a magnetic field. Polarized light propagated through the optical fiber is detected at its outlet independent of environmentally induced low frequency variations whereby the sensor may be maintained at quadrature and maximum sensitivity.
TL;DR: In this article, an apparently undocumented loss mechanism in monomode fibers with germanium doped cores is demonstrated and the constraints on fiber design as a consequence of this loss mechanism are discussed.
Abstract: An apparently undocumented loss mechanism in monomode fibers with germanium doped cores is demonstrated. This loss increases as the fiber drawing temperature and/or the germanium concentration increases. By consideration of this mechanism in the fiber design and fabrication, losses lower than previously reported have been achieved both in fiber with low germanium concentration (0.38 dB/km at 1.3 μm) and in higher doped, dispersion shifted fiber (0.37 dB/km at 1.55μm). The constraints on fiber design as a consequence of this loss mechanism are discussed.
TL;DR: Various types of polarization eigenstates of a twisted birefringent fiber are discussed, and the resulting group delay difference is derived.
Abstract: Real single-mode fibers generally exhibit elliptical birefringence caused by deviations of the core shape from circularity, by transverse internal stress, and by residual twist. These three contributions can be individually determined by analyzing on a Poincare sphere the wavelength dependence of the output state of polarization of a short section of fiber with fixed input polarization. Various types of polarization eigenstates of a twisted birefringent fiber are discussed, and the resulting group delay difference is derived.
TL;DR: In this paper, a doubly clad single-mode fiber has been fabricated through the MCVD process, design criteria with due regard to fabrication conditions that optimize fiber structure have also been investigated.
Abstract: A new type of doubly clad single-mode fiber has been fabricated through the MCVD process, Design criteria with due regard to fabrication conditions that optimize fiber structure have also been investigated As a result of determination of these criteria, a dispersion-minimized single-mode fiber with an index difference between core and outer cladding Δ 1 equal to 052 percent, an index difference between outer and inner cladding Δ 2 equal to -031 percent, a core diameter 2a = 132 \mu m, and t/a = 051 has been fabricated The absolute value of the total dispersion of the fiber has been reduced to within ± 1 ps/km/nm in the 132-143 \mu m spectral range
TL;DR: Highly accurate determination of the outer diameter of unclad glass fibers has been achieved by analyzing, at fixed scattering angle, the wavelength dependence of elastically scattered radiation.
Abstract: Highly accurate determination of the outer diameter of unclad glass fibers has been achieved by analyzing, at fixed scattering angle, the wavelength dependence of elastically scattered radiation. The positions of resonance peaks in the scattering spectrum are strongly dependent on fiber diameter. The linewidths of the peaks are sensitive to the circularity of the fiber cross section and to optical loss within or on the fiber surface. This new technique may be useful for the characterization of optical-communication fibers.
TL;DR: A Faraday circulator or isolator that uses a silica-core, single-mode, birefringent fiber as the active medium and small permanent magnets for the magnetic field is demonstrated.
Abstract: We demonstrate a Faraday circulator or isolator that uses a silica-core, single-mode, birefringent fiber as the active medium and small permanent magnets for the magnetic field. Circulators were constructed for wavelengths of 632.8 and 830 nm using about 2 m of fiber. This is the first description to our knowledge of such potentially useful working devices made in birefringent fiber. Bandwidth and temperature dependence were also investigated.
TL;DR: The efficient conversion of 1.06-μm radiation in a graded-index multimode optical fiber oscillator into a small number of spectral components propagating in specific modes of the fiber and falling in the spectral range spanning from the blue to 1.53 μm is reported.
Abstract: The efficient conversion of 1.06-μm radiation in a graded-index multimode optical fiber oscillator into a small number of spectral components propagating in specific modes of the fiber and falling in the spectral range spanning from the blue to 1.53 μm is reported. The effect is shown to result primarily from phase-matched four-photon mixing. The converted light is found to propagate as individual fiber modes which are identified. The wavelengths of the spectral components of the output of the oscillator are governed primarily by fiber geometry. Analysis of the results also indicates the presence and gives a measure of the fiber-core birefringence sensed by low-order modes of propagation of the graded-index multimode fibers we have studied. The efficiency of the oscillator source and the specific characteristic wavelengths available with common graded-index fibers suggest several possible applications, which are discussed.
TL;DR: By stabilizing the fiber cavity, this work achieved stable single-frequency Brillouin-laser output with a linewidth determined primarily by the 100-kHz modulation used in the feedback system.
Abstract: The detailed behavior of the cw stimulated Brillouin fiber laser has been studied by using a narrow-linewidth cw pump argon laser at 5145 A and an 83-m fiber ring cavity. By stabilizing the fiber cavity, we achieved stable single-frequency Brillouin-laser output with a linewidth determined primarily by the 100-kHz modulation used in the feedback system. Lasing threshold for the 4.5-μm-core fiber used was observed at a pump power of 77 mW, and the maximum Brillouin output was 13 mW for a pump of 320 mW. The Brillouin gain medium was shown to exhibit homogeneouslike behavior.