Showing papers on "Polarization mode dispersion published in 1982"
TL;DR: In this paper, the authors demonstrate wavelength averaging of the power in either mode, permitting a simple measurement of power transfer to the cross-polarized mode as a function of fiber length, and confirm experimentally the theory of random mode coupling between the polarization modes.
Abstract: Perturbations in highly birefringent single-mode fibers couple the two polarization modes and degrade the polarization-holding ability. With a broadband source we demonstrate wavelength averaging of the power in either mode, permitting a simple measurement of the power transfer to the cross-polarized mode as a function of fiber length. Using this technique, we confirm experimentally the theory of random mode coupling between the polarization modes.
93 citations
TL;DR: In this article, the degree of polarization degradation in anisotropic single-mode fibers is investigated in terms of light source spectrum, incident polarization condition, and fiber parameters. But the degradation is determined by the mutual correlation function γ, between the two modes, which depends on the light source spectra, fiber polarization dispersion, and the fiber length.
Abstract: The degree of polarization for propagation waves in anisotropic single-mode fibers is formulated in terms of light source spectrum, incident polarization condition, and fiber parameters. The polarization degree deterioration is based on the incident wave split into two eigenpolarization modes inherent in the fiber. Since the two eigenpolarization modes have different group velocities from each other, the degree of polarization is degraded when both of the modes are excited. Polarization degree is preserved when only one of the eigen-polarization modes is excited. The degradation is determined by the mutual correlation function γ, between the two modes, which depends on the light source spectra, fiber polarization dispersion, and fiber length.
57 citations
CNET1
TL;DR: In this article, a simple and accurate approximation of modal dispersion in single-mode optical fibres deduced from spectral behaviour of mode spot size is presented. But neither knowledge of index profile nor of maximum refractive index difference are required in this approximation.
Abstract: We report a simple and accurate approximation of modal dispersion in single-mode optical fibres deduced from spectral behaviour of mode spot size; neither knowledge of index profile nor of maximum refractive index difference are required in this approximation.
47 citations
TL;DR: In this article, the mode coupling parameters between the orthogonally polarized HE 11 modes are compared for various kinds of waveguide imperfections and ambient fluctuations in the stress-applied single polarization fibers.
Abstract: Mode coupling effects caused by waveguide imperfections and ambient fluctuations in the stress-applied single polarization fibers have been investigated. Several origins of mode coupling, such as: 1) core deformations, 2) deformation of stress-applying parts, 3) micro-bending, and 4) temperature fluctuations, have been treated. The mode coupling parameters between the orthogonally polarized HE 11 modes are compared for various kinds of waveguide imperfections and ambient fluctuations. It was clarified that the deformation of the stress-applying parts is the dominant factor in the mode coupling effects in stress-applied single polarization fibers.
42 citations
TL;DR: In this paper, the optimum waveguide structure for linearly single polarization fibers, which satisfies the large modal birefringence and the zero polarization mode dispersion simultaneously, has been investigated.
Abstract: The optimum waveguide structure for linearly single polarization fibers, which satisfies the large modal birefringence and the zero polarization mode dispersion simultaneously, has been investigated. The basic waveguide structure is the single-mode optical fiber that has an elliptical core and stress-applying parts with a different expansion coefficient from that of the cladding. Waveguide parameters, such as index difference, core ellipticity, and cutoff wavelength, are first determined to obtain highly birefringent fibers with B = 1 \times 10^{-5} or B = 5 \times 10^{-5} . The structure of the stress-applying parts that provides zero polarization mode dispersion is then determined.
39 citations
TL;DR: In this paper, a sinusoidal technique is proposed to measure chromatic dispersion in optical fibers, which is based on the phase shift of the light beam along a fiber when its wavelength is changed.
Abstract: A sinusoidal technique is reported, which allows simple and accurate measurements of chromatic dispersion in optical fibers. It is based on the phase shift which a sinusoidally modulated light beam undergoes while traveling along a fiber when its wavelength is changed. The choice of a multiple LED's source permits the continuous spectral covering from 750 to 1600 nm; easily available instrumentation and devices are needed for the measurement setup. The technique is reported in detail by showing results obtained in multimode fibers; statistical evaluation of its accuracy and a comparison with conventional methods are carried out. An accuracy of a few picosecond in relative delay and of /spl I.chemc/1 ps/nm /spl dot/ km in chromatic dispersion are demonstrated, that compare very favorably with the existing techniques.
37 citations
TL;DR: Calculations show that, under appropriate circumstances, a fiber filter of length shorter than 2 cm can equalize dispersion from an OC link about 1 km long.
Abstract: The anomalous dispersion characteristic of recently reported [Opt. Lett. 5, 476 (1980)] optical-fiber filters is proposed for use in equalization of material dispersion in optical-communication (OC) links employing single-mode fibers. Calculations show that, under appropriate circumstances, a fiber filter of length shorter than 2 cm can equalize dispersion from an OC link about 1 km long.
35 citations
TL;DR: In this paper, a spatial technique based on a visibility maximum position measurement in an interferometer was used to measure the wavelength dependence of the modal dispersion by varying optical source wavelength between 821 and 904 nm.
Abstract: Polarization mode dispersion in elliptical core single-mode fibers has been measured by a spatial technique based on a visibility maximum position measurement in an interferometer. Using the technique, wavelength dependence of the modal dispersion has been measured by varying optical source wavelength between 821 and 904 nm. As a result, contribution of geometrical and strain birefringences on the modal dispersion has been evaluated, and normalized frequency dependence of the modal dispersion has been clarified. Moreover, the dispersion compensation effect has been observed by interchanging the fast and slow modes of two fibers at a splice point. The experimental results reveal that the spatial technique is very useful for polarization mode dispersion measurement.
26 citations
13 Apr 1982
TL;DR: In this article, a polarization-maintaining and absorption-reducing (PANDA) fiber was proposed, which provides large modal birefringence and low-loss properties.
Abstract: Single-mode and low-loss optical fibers maintaining a state of polarization over a long length are necessary for coherent optical communication and fiber-optic sensing systems.1 Stress-induced birefringence fibers as reported so far show the high losses.2 Polarization mode dispersion (PMD) of these fibers is measured to be of the order of 50300 psec/km, which causes degradation of the receiver sensitivity in coherent optical communication systems. This paper presents polarization-maintaining and absorption-reducing (PANDA) fibers, which provide large modal birefringence and low- loss properties. Furthermore, the structure of PANDA fibers with zero PMD is proposed.
24 citations
TL;DR: In this article, the degree of polarization degradation in anisotropic single-mode fibers is investigated in terms of light source spectrum, incident polarization condition, and fiber parameters. But the degradation is determined by the mutual correlation function gamma, between the two modes, which depends on the light source spectra, fiber polarization dispersion, and the fiber length.
Abstract: The degree of polarization for propagation waves in anisotropic single-mode fibers is formulated in terms of light source spectrum, incident polarization condition, and fiber parameters. The polarization degree deterioration is based on the incident wave split into two eigenpolarization modes inherent in the fiber. Since the two eigenpolarization modes have different group velocities from each other, the degree of polarization is degraded when both of the modes are excited. Polarization degree is preserved when only one of the eigenpolarization modes is excited. The degradation is determined by the mutual correlation function gamma, between the two modes, which depends on the light source spectra, fiber polarization dispersion, and fiber length.
22 citations
TL;DR: In this article, the deviations from the group delays expected for the optimum power-law index profile are numerically calculated for several types of undesired fibers using a scalar multilayer approximation method.
Abstract: The deviations from the group delays expected for the optimum power-law index profile are numerically calculated for several types of undesired fibers using a scalar multilayer approximation method. This paper shows the way two fibers are selected from among undesired fibers so that the fiber spliced to each other becomes broad band.
TL;DR: In this article, the effect of the change in refractive index across the fiber was quantified and it was shown that the waveguide dispersion of the fundamental mode by the fiber is virtually unaffected by the polarization properties of the fiber.
Abstract: In the weak-guidance approximation, the properties of fundamental modes of optical fibers depend on solutions of the scalar-wave equation and contain no polarization effects that are due to the fiber. In this paper, we derive polarization-dependent corrections for the clad power-law and infinite parabolic profiles to quantify the effect of the change in refractive index across the fiber. In particular, the waveguide dispersion of the fundamental mode by the fiber is found to be virtually unaffected by the polarization properties of the fiber.
CNET1
TL;DR: In this article, a simple calculation allowing the prediction of the modal dispersion in single-mode optical fibres from the spectral behaviour of the mode spot size and the profile index is presented.
Abstract: We report a simple calculation allowing the prediction of the modal dispersion in single-mode optical fibres from the spectral behaviour of the mode spot size and the profile index.
TL;DR: In this article, the optimum waveguide structure for linearly single polarization fibers, which satisfies the large modal birefringence and the zero polarization mode dispersion simultaneously, has been investigated.
Abstract: The optimum waveguide structure for linearly single polarization fibers, which satisfies the large modal birefringence and the zero polarization mode dispersion simultaneously, has been investigated. The basic waveguide structure is the single-mode optical fiber that has an elliptical core and stress-applying parts with a different expansion coefficient from that of the cladding. Waveguide parameters, such as index difference, core ellipticity, and cutoff wavelength, are first determined to obtain highly birefringent fibers with B = 1 X 10/sup -5/ or B = 5 X 10/sup -5/. The structure of the stress-applying parts that provides zero polarization mode dispersion is then determined.
TL;DR: In this article, the dispersion sensitivity to small changes in index-differences, radius, and wavelength is investigated in the case of dispersion free single-mode fibers, and the tolerances on the various parameters can then be deduced: singly and doublyclad structures are compared.
Abstract: The dispersion sensitivity to small changes in index-differences, radius, and wavelength is investigated in the case of dispersion free single-mode fibers. If a minimum bandwidth is required, tolerances on the various parameters can then be deduced: singly- and doubly-clad structures are compared. Constant reference is made to the HE 11 mode spot-size to relate dispersion properties and attenuation. A nonzero fundamental mode cutoff is shown to induce an enhanced sensitivity to a change in fiber geometrical characteristics. The effect of dopant diffusion and axial dip on dispersion is then considered and conclusions are drawn concerning the use of profiles measured on preforms to predict fiber propagation properties.
TL;DR: In this paper, the dispersion sensitivity to small changes in index-differences, radius, and wavelength is investigated in the case of dispersion free single-mode fibers, and the tolerances on the various parameters can then be deduced: singly and doublyclad structures are compared.
Abstract: The dispersion sensitivity to small changes in index-differences, radius, and wavelength is investigated in the case of dispersion free single-mode fibers. If a minimum bandwidth is required, tolerances on the various parameters can then be deduced: singly- and doubly-clad structures are compared. Constant reference is made to the HE/sub 11/ mode spot-size to relate dispersion properties and attenuation. A nonzero fundamental mode cutoff is shown to induce an enhanced sensitivity to a change in fiber geometrical characteristics. The effect of dopant diffusion and axial dip on dispersion is then considered and conclusions are drawn concerning the use of profiles measured on preforms to predict fiber propagation properties.
TL;DR: In this paper, the intrinsic angular momentum associated with the direction of circular polarization in space can, as we know, have two different orientations, and the states of the polarization or the directions of the polarities have been considered so far to be invariant.
Abstract: For a given modal skew ray in a graded-index optical fiber, the intrinsic angular momentum associated with the direction of circular polarization in space can, as we know, have two different orientations, and the states of the polarization or the directions of the polarization have been considered so far to be invariant. This paper shows that this is valid only for high frequencies but fails for low frequencies and in certain special optical fibers. A critical frequency is calculated at which the direction of rotation of its circular polarization changes. It is pointed out that the feature of this anomalous polarization critically depends on the inhomogeneity of the medium. Some profiles of refractive index are examined.
01 Jan 1982
TL;DR: In this paper, a distinction has to be made between the preservation of the integrity and of the direction of the polarization of the guided wave in optical fiber, and a fiber with a perfectly circular core can preserve integrity but not necessarily direction whilst a bi-refringent fiber might do both even if it were bent or twisted to some extent.
Abstract: When considering polarization in optical fiber, a distinction has to be made between the preservation of the integrity and of the direction of the polarization of the guided wave. For instance, a fiber with a perfectly circular core (1) could preserve integrity but not necessarily direction whilst a bi-refringent fiber might do both even if it were bent or twisted to some extent. A fiber which preserves integrity and direction should ideally support only a single polarized mode. This would be a simple matter with microwaves in a metal waveguide, but fibers, as dielectric guides, have no lower cut-off for the fundamental modes so that it is not possible to use the shape of the waveguide section to cut-off one fundamental mode and leave the other. See Figure (1).
13 Apr 1982
TL;DR: In this paper, the results of chromatic dispersion measurements performed by selectively exciting different groups of mode are presented, showing that the wavelength of zero material dispersion is dependent on the propagating mode volume with practical impact on system design.
Abstract: Chromatic dispersion in optical fibers is a result of material and waveguide effects. In graded-index fibers there could be a contribution from nonlinear dispersive properties of the core material, although it has been claimed that such an effect is negligible.1 All these factors affect each mode in a different way. Therefore, determination of the wavelength of zero material dispersion (ZMD) is dependent on the propagating mode volume with practical impact on system design. Measurement of chromatic dispersion properties of different modes can in principle give some information about these problems. In this paper we show results of chromatic dispersion measurements performed by selectively exciting different groups of mode.
TL;DR: In this article, a method based on moments of the profile function rather than its precise shape was proposed to characterize optical fiber refractive-index profiles perturbed near the fiber axis.
Abstract: Optical-fiber refractive-index profiles perturbed near the fiber axis are characterized by using a new method based on moments of the profile function rather than its precise shape. The method is applied to waveguide dispersion for the fundamental mode, and results of widespread applicability are obtained. For step-index fibers perturbed out to 0.4 of the fiber-core radius, the dispersion behavior is described in terms of two parameters encompassing all possible perturbations. It is argued that it is more appropriate to study waveguide dispersion at the point at which the effective waveguide parameter V¯=3 rather than to concentrate on the point of zero dispersion.
TL;DR: In this article, the mathematical separation of multimode dispersion and material dispersion on the overall dispersion of an optical fiber was shown and relations derived can be used to evaluate the resultant baseband frequency response of a fiberguide with the use of light sources of various spectral bandwidth.
Abstract: The mathematical separation of multimode dispersion and material dispersion on the overall dispersion of an optical fiber will be shown in this letter. The relations derived can be used to evaluate the resultant baseband frequency response of a fiberguide with the use of light sources of various spectral bandwidth. The approximate description of the baseband frequency response characteristics of individual fiber sections permits one to estimate the resultant transmission bandwidth of the fiberguide line.
TL;DR: In this article, the wavelength shift of a semiconductor laser during triangular pulse modulation has been investigated, using both a Michelson interferometer and direct spectral measurements, and a theoretical investigation shows under what conditions the method is equivalent to the standard dispersion measurement setup.
Abstract: The wavelength shift of a semiconductor laser during triangular pulse modulation has been investigated, using both a Michelson interferometer and direct spectral measurements. This property is used to establish a method for high-resolution dispersion measurements limited to 10 ps, and not affected by material dispersion or detector rise time. A theoretical investigation shows under what conditions the method is equivalent to the standard dispersion measurement setup. The technique is applied to measure polar mode dispersion in single-mode fibers. Examples of polarization noise caused by polarization anisotropy and the variation of source wavelength are presented.