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Showing papers on "Polarization mode dispersion published in 1993"


Journal ArticleDOI
TL;DR: In this article, a specific fiber dispersion management is proposed allowing the simultaneous suppression of linear dispersion penalties and of degradations arising from parametrical fiber nonlinearities, and the number of optical channels that can be transmitted over 1000 km at a bit rate of 2.5 Gb/s is only limited by the available optical amplifier bandwidth.
Abstract: A specific fiber dispersion management is proposed allowing the simultaneous suppression of linear dispersion penalties and of degradations arising from parametrical fiber nonlinearities. For the proposed dual dispersion configuration (DDCON) the number of optical channels that can be transmitted over 1000 km at a bit rate of 2.5 Gb/s is only limited by the available optical amplifier bandwidth. >

140 citations


Journal ArticleDOI
TL;DR: All fiber designs use only the fundamental LP01 mode for dispersion compensation and can account for first- and second-order dispersion effects.
Abstract: Single-mode dispersion compensating fiber designs with absolute dispersion values of greater than 100 ps/(nm km) are described. A multiclad fiber with a triangular refractive-index profile in the core gives a dispersion of −250 ps/(nm km), resulting in a 15:1 compensation scheme. All fiber designs use only the fundamental LP01 mode for dispersion compensation and can account for first- and second-order dispersion effects.

95 citations


Journal ArticleDOI
B.L. Heffner1
TL;DR: In this paper, a fast, automated system based on a tunable laser and an accurate, real-time polarimeter is used to measure DGD, DGDD, and PSP variation by eigenanalysis of Jones matrices measured at a series of discrete wavelengths, and the system accuracy is demonstrated.
Abstract: Polarization mode dispersion can be described to first order by principal states of polarization (PSPs) and a differential group delay (DGD), and to second order by wavelength variation of the PSPs and by DGD dispersion (DGDD), the wavelength derivative of DGD. The high accuracy and wavelength resolution of Jones matrix eigenanalysis allows precise measurement of DGDD and PSP variation. A fast, automated system based on a tunable laser and an accurate, real-time polarimeter is used to measure DGD, DGDD, and PSP variation by eigenanalysis of Jones matrices measured at a series of discrete wavelengths, and the system accuracy is demonstrated. Measurements at 2-nm intervals of a device whose DGDD is a known function of wavelength yield values of DGDD which differ from theory by less than 13 fs/nm. >

93 citations


Journal ArticleDOI
TL;DR: Polarization mode dispersion of installed optical cables and of short concatenations of hi-bi fibers have been measured with polarimetric and interferometric instruments as discussed by the authors, and the results confirm the theoretical models, in particular the predicted relations between the two measurement methods.
Abstract: Polarization mode dispersion of installed optical cables and of short concatenations of hi-bi fibers have been measured with polarimetric and interferometric instruments. The results confirm the theoretical models, in particular the predicted relations between the two measurement methods. The importance of a statistical treatment of polarization mode dispersion is underscored by the observed instability of the principal states and the remarkable long-term stability of their statistics. >

74 citations


Journal ArticleDOI
TL;DR: A white-light interference phenomenon arising between polarization modes as a result of mode coupling induced by a pointlike lateral force applied in approximately one half the length of the tested fiber permits the use of a Wollaston prism without a delay line as an analyzing interferometer.
Abstract: A method for measuring modal birefringence and polarization mode dispersion in highly birefringent fibers is presented. It employs a white-light interference phenomenon arising between polarization modes as a result of mode coupling induced by a pointlike lateral force applied in approximately one half the length of the tested fiber. This permits the use of a Wollaston prism without a delay line as an analyzing interferometer. Results of measurements of modal birefringence and polarization mode dispersion at λ(0)= 826 nm are reported for four commercially available fibers: the York Bow-Tie, the Fujikura Panda, the Andrew E-type, and the Andrew D-type.

63 citations


Patent
10 Jun 1993
TL;DR: In this paper, the authors proposed an automatic operation of a polarization controller using a steepest-descent method based on a distortion measure of the received signal for the optical signal transmitted through the optical fiber to generate control signals which are used to control the polarization controller.
Abstract: The polarization-dependent distortion of an optical signal transmitted through an optical fiber is reduced by aligning the polarization of the optical signal to minimize the received signal distortion. A polarization controller (a device which can change the polarization of light in an optical fiber) may be located at either the input or output end of a long haul optical fiber system and is used to align the polarization of the signal to minimize the received signal distortion. Automatic operation of the polarization controller can be obtained by using a steepest-descent method based on a distortion measure of the received signal for the optical signal transmitted through the optical fiber to generate control signals which are used to control the polarization controller.

56 citations



Journal ArticleDOI
TL;DR: In this paper, the authors investigate experimentally and theoretically two mechanisms for nonlinear distortion when polarization-mode dispersion (PMD) is present in single-mode fiber using chirped sources.
Abstract: Analog transmission in single-mode fiber using chirped sources gives rise to nonlinear distortion when polarization-mode dispersion (PMD) is present. We investigate experimentally and theoretically two mechanisms for this distortion: for chirped sources, PMD in the presence of polarization-mode coupling results in second-order distortion that is proportional to the square of the modulation frequency; when polarization-dependent loss is present, an additional second-order distortion term occurs that is independent of modulation frequency. Both mechanisms give rise to distortion that is time varying due to the sensitivity of PMD to ambient temperature changes. Numerical examples indicate that these effects can limit the capacity of analog systems that use directly modulated semiconductor lasers. >

52 citations


Journal ArticleDOI
TL;DR: In this paper, the impact of polarization mode dispersion on long distance IM-DD systems was analyzed both theoretically and experimentally by means of a 2.5 Gb/s synchronous digital hierarchy (SDH) commercial system.
Abstract: Polarization mode dispersion can influence long distance IM-DD systems especially when optical amplifiers are used to increase the unrepeated link length. The impact of this phenomenon is analyzed in this letter both theoretically and experimentally by means of a 2.5 Gb/s synchronous digital hierarchy (SDH) commercial system. Polarization dispersion has a nonnegligible impact on the system performance when the associated differential group delay is of the order of 100 ps. >

47 citations


Patent
Neal S. Bergano1
23 Dec 1993
TL;DR: In this article, the problem of signal-to-noise ratio fading over long optical transmission paths is overcome by dynamically controlling an optical signal source having two signal components each with a different wavelength.
Abstract: The problems relating to Signal-to-noise ratio fading over long optical transmission paths are overcome by dynamically controlling an optical signal source having two signal components each with a different wavelength, where the parameters to be controlled include the wavelengths of the two signal components, the relative and absolute states of polarization of the two signal components, and the relative delays between the data patterns carried by the two signal components so that the polarization of the two signal components of the optical signal are continuously reoptimized in the presence of polarization dependent loss, polarization mode dispersion, polarization dependent hole burning, and fiber nonlinearities.

41 citations


Patent
26 May 1993
TL;DR: In this article, a polarization-independent optical isolator having a structure in which polarization dispersion is virtually eliminated by selecting the thickness and optical axis orientations of birefringent crystalline plates used in the isolator is disclosed.
Abstract: A polarization-independent optical isolator having a structure in which polarization dispersion is virtually eliminated by selecting the thickness and optical axis orientations of birefringent crystalline plates used in the isolator is disclosed. The optical isolator of the present invention employs a combination of birefringent crystalline plates wherein the optical axis orientation of at least one birefringent crystalline plate in the optical isolator is different from the optical axis orientation of the remaining birefringent crystalline plates, and the polarization mode dispersion, which is induced when the beam propagates through the birefringent crystalline plate having a different optical axis orientation, is equal to the dispersion rate of the polarization mode dispersion attributable to the remaining birefringent crystalline plates and in a mutually inverse direction.

Patent
29 Dec 1993
TL;DR: An optical isolator as discussed by the authors utilizes a pair of polarization selective elements, as for example birefringent wedges, and all integral Faraday rotator aligned therewith to perform optical signal isolation without introducing the polarization mode dispersion inherent in conventional polarization independent optical isolators.
Abstract: An optical isolator utilizes a pair of polarization selective elements, as for example birefringent wedges, and all integral Faraday rotator aligned therewith to perform optical signal isolation without introducing the polarization mode dispersion inherent in conventional polarization independent optical isolators. Optical isolation is accomplished by passing a forward-directed optical signal through a first birefringent element which separates the optical signal into two orthogonal states. The two orthogonal polarization states exchange identities upon entering the second birefringent element from the Faraday rotation element and are again deflected by the second birefringent element so that they emerge from the second element parallel to each other and, having traveled the same optical path length, witllout any polarization mode dispersion. Both polarization states of the reverse propagating optical signal are sufficiently angularly deflected to avoid coupling with the optical signal path.

Patent
30 Sep 1993
TL;DR: In this article, a controlled amount of twist is imparted to each optical fiber uniformly along its entire length, which reduces twist induced strain and promotes optimum PMD reduction, and is shown to improve the performance of fiber optic cable fabricated in accordance with the principles of the invention.
Abstract: Improved PMD performance is achieved in fiber optic cable fabricated in accordance with the principles of the invention by twisting each of a plurality of optical fibers in a controlled manner as the cable is being formed. A controlled amount of twist is imparted to each optical fiber uniformly along its entire length. Uniformity of twist reduces twist-induced strain and promotes optimum PMD reduction.

Proceedings ArticleDOI
21 Feb 1993
TL;DR: In this paper, the polarization-dependent properties of fiber and optical components may limit the use of potential broadband characteristics and polarization-multiplexing ability in next-generation transoceanic optical networks.
Abstract: In next-generation transoceanic optical networks the polarization-dependent properties of fiber and optical components may limit the use of potential broad-band characteristics and polarization-multiplexing ability.1,2 Namihira reported an optical isolator that had a polarization-mode dispersion of 0.8 ps, which is relatively large compared with the 0.1 − ps / km square-root dependence of the dispersion of optical-fiber cable.

Journal ArticleDOI
Brian L. Heffner1
TL;DR: This permits what is to the author's knowledge the first complete measurement of the polarization mode dispersion (PMD) of straight, submeter lengths of optical fiber.
Abstract: A new technique is presented for the measurement of the differential group delay (DGD) between principal states of polarization of an optical device, with a demonstrated accuracy and resolution of roughly 50 attoseconds (50 × 10−18 s). Accuracy was directly assessed by measurement of a crystal-quartz DGD Standard. This permits what is to the author's knowledge the first complete measurement of the polarization mode dispersion (PMD) of straight, submeter lengths of optical fiber. PMD can be reliably measured only when the fiber is straight, since spooling of the fiber changes its PMD by introducing additional mode coupling. Measurement of four fiber samples revealed correlation between DGD and fiber core ovality.

Journal ArticleDOI
01 Sep 1993
TL;DR: Using an exact waveguide analysis and measured stress profiles, it is shown that a delicate interplay between form-induced and stress-induced contributions to polarization mode dispersion in dispersion-shifted fibers can significantly reduce intrinsic short-length polarization mode dispersions.
Abstract: Using an exact waveguide analysis and measured stress profiles, we show that a delicate interplay between form-induced and stress-induced contributions to polarization mode dispersion in dispersion-shifted fibers can significantly reduce intrinsic short-length polarization mode dispersions. Our observations also indicate that the ovality of fibers is not a true indicator of long-length polarization mode dispersion in production-quality cabled fibers.

Patent
Naoya C1, Shogo c1, Tomoki C
16 Jun 1993
TL;DR: In this paper, an optical communication transmission system including an optical amplifier lumped repeater system of the present invention includes, for the purpose of preventing degradation of the transmission characteristic arising from wavelength dispersion of optical fibers due to the raised power of the optical signal, transmission optical fibers provided for all or most of the repeating sections and having wavelengths dispersion values set to different values from zero to zero.
Abstract: An optical communication transmission system including an optical amplifier lumped repeater system of the present invention includes, for the purpose of preventing degradation of the transmission characteristic arising from wavelength dispersion of optical fibers due to raised power of the optical signal, transmission optical fibers provided for all or most of the repeating sections and having wavelength dispersion values set to different values from zero, and optical fibers provided for the individual sections to compensate for the sum of wavelength dispersion of the sections so as to reduce the total wavelength dispersion to zero. The optical fiber for compensation for each section may be replaced by a substitutive compensation element. Alternatively, very small wavelength dispersion which remains due to failure in compensating to zero dispersion may be compensated for using a dispersion equalizer of an electric system in the reception section.

Journal ArticleDOI
TL;DR: An experimental measurement of group-velocity dispersion in a tunable actively mode-locked erbium-doped fiber laser confirms the validity of the method, which requires the knowledge of the cold-cavity loss along with the gain and absorption spectrum of the active medium.
Abstract: Erbium doping introduces a resonant contribution to the group-velocity dispersion of the amplifier host fiber. A method for evaluating the erbium-induced group-velocity dispersion is proposed. This dispersion method requires the knowledge of the cold-cavity loss along with the gain and absorption spectrum of the active medium. An experimental measurement of group-velocity dispersion in a tunable actively mode-locked erbium-doped fiber laser confirms the validity of the method.

Journal ArticleDOI
TL;DR: In this article, the effect of fiber polarization mode dispersion (PMD) on a coherent optical system with pilot carrier is twofold: first, the PMD causes state of polarization (SOP) mismatch between the message signal and the pilot carrier.
Abstract: The effect of fiber polarization mode dispersion (PMD) on a coherent optical system with pilot carrier is twofold. First, the PMD causes state of polarization (SOP) mismatch between the message signal and the pilot carrier. Second, the degrees of polarization (DOPs) of the message signal and pilot carrier are degraded by PMD. Because coherent reception relies both on the SOPs and DOPs of the waves, system performance is degraded by PMD. The effect of SOP mismatch causes intermediate frequency (IF) signal amplitude degradation, whereas DOP variation not only results in IF signal amplitude degradation but further induces IF noises. Analytical expressions are derived to evaluate the performance degradation. It is shown that there is no performance degradation if only one principle state of polarization is excited and maximum degradation occurs when both principle states of polarization are equally excited. It is found that significant degradation may happen when large differential group delay exists. >

Proceedings ArticleDOI
21 Feb 1993
TL;DR: In this article, a commercial optical time-domain re-flectometer (OTDR) with a polarizer/analyzer pair is used to measure short-length PMD in fibers.
Abstract: Polarization mode dispersion (PMD) in dispersion-shifted fibers presents an inherent limitation in ultralong-distance communications systems. The advent of multigigabit-per-second systems and CATV applications makes it imperative that a good measure of PMD be obtained during fiber manufacture. Several techniques for the measurement of short-length PMD in fibers are currently available.1 A typical spool of fiber, however, has PMD values that vary along the length owing to minor perturbations during fabrication. As a result, a short-length PMD measurement on a specific section of a fiber made by using any of the techniques does not provide a complete knowledge of the statistical spread of PMD over the entire length. In this paper we show that by modifying a commercial optical time-domain re- flectometer (OTDR) with a polarizer/analyzer pair, one can measure short-length PMD’s in fibers.

Proceedings ArticleDOI
A. F. Judy1, J. B. Haber1, William B. Gardner1, W. T. Greene1, A. J. Ritger1, K. L. Walker1 
21 Feb 1993
TL;DR: This paper presents the first major PMD characterization for cabled MCVD fiber characterization and shows that MCVD fibers fabricated with optimized processing conditions meet the stringent PMD demands of evolving systems.
Abstract: PMD is becoming an important parameter to specify for high bit rate and analog transmission systems. Values of ~ 0.1 ps/√km are desired for maximum performance of ultra-long, amplified undersea systems. Almost as demanding, high- capacity analog video systems may need total route PMD < 4 ps.[1] Consequently, cable PMD measurements and verification are becoming necessary to ensure system performance. This paper presents the first major PMD characterization for cabled MCVD fibers and shows that MCVD fibers fabricated with optimized processing conditions meet the stringent PMD demands of evolving systems.

Journal ArticleDOI
TL;DR: In this paper, the effect of random polarization mode coupling and polarization dependent losses on polarization mode dispersion (PMD) was investigated for single-mode fibers with random polarization modes.

Proceedings ArticleDOI
Douglas P. Karim1
09 Feb 1993-Fibers
TL;DR: In this article, the effects of launching conditions and fiber numerical aperture on bandwidth are discussed, and a method of realizing higher effective bandwidth over a given fiber by mode-selective detection is presented.
Abstract: Pulse broadening in large core step-index optical fibers is dominated by multimode dispersion. The bandwidth of PMMA core polymer optical fiber depends on launch conditions, being substantially greater for collimated input than for mode-filled launching. The dispersion behavior is significantly affected by both mode dependent attenuation and by power coupling between modes. The results of time-domain dispersion measurements performed at 650 nm are presented and examined. The effects of launching conditions and fiber numerical aperture on bandwidth are discussed. Mode conversion is studied by examining far-field output patterns under various launch conditions. Disturbances caused by sharp bends, splices, and couplers can modify the distribution of energy among modes and thus effect the dispersion. Because only the propagation after the disturbance is effected, a given fiber optic link can have different effective bandwidths in the two counter propagating directions. Finally, a method of realizing higher effective bandwidth over a given fiber by mode-selective detection is presented.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Patent
Henmi Naoya1, Nakaya Shogo1, Saito Tomoki1
16 Jun 1993
TL;DR: In this paper, an optical communication transmission system including an optical amplifier lumped repeater system of the present invention includes, for the purpose of preventing degradation of the transmission characteristic arising from wavelength dispersion of optical fibers due to the raised power of the optical signal, transmission optical fibers provided for all or most of the repeating sections and having wavelengths dispersion values set to different values from zero to zero.
Abstract: An optical communication transmission system including an optical amplifier lumped repeater system of the present invention includes, for the purpose of preventing degradation of the transmission characteristic arising from wavelength dispersion of optical fibers due to raised power of the optical signal, transmission optical fibers provided for all or most of the repeating sections and having wavelength dispersion values set to different values from zero, and optical fibers provided for the individual sections to compensate for the sum of wavelength dispersion of the sections so as to reduce the total wavelength dispersion to zero. The optical fiber for compensation for each section may be replaced by a substitutive compensation element. Alternatively, very small wavelength dispersion which remains due to failure in compensating to zero dispersion may be compensated for using a dispersion equalizer of an electric system in the reception section.

Proceedings ArticleDOI
04 Apr 1993
TL;DR: In this article, the optical noise is induced from the amplifier spontaneous emission (ASE), the chromatic dispersion, the polarization mode dispersion (PMD), the polarization dependent loss (PDL), the nonlinear effects (NL), etc.
Abstract: Remarkable progress has been made on ultra-long high bit rate transoceanic transmission systems using Erbium-doped fiber amplifiers (EDFAs) [1,2]. It is noted that in EDFA systems, the optical noise is amplified together with the optical signals and accumulated along the whole length of the transmission systems. The optical noise is induced from the amplifier spontaneous emission (ASE), the chromatic dispersion [3], the polarization mode dispersion (PMD) [4,5], the polarization dependent loss (PDL), the nonlinear effects (NL), etc.

Proceedings ArticleDOI
09 Feb 1993-Fibers
TL;DR: In this article, temperature cycling a spool of fiber using an oven was used to determine the distribution of PMD effects, generating over 1000 independent PMD samples in a few hours.
Abstract: If this paper, we discuss techniques for measuring polarization mode dispersion (PMD) effects in experimental systems. Because PMD varies with time due to changes in temperature, pressure, and fiber position, measurements of PMD effects in a typical experimental system may not show worst case events or give a true indication of the distribution of these effects over the lifetime of a system. Here we show that by temperature cycling a spool of fiber using an oven, we can quickly determine the distribution of PMD effects, generating over 1000 independent PMD samples in a few hours. This permits the experimental study of events occurring with less than a 10-3 probability and, in systems with only linear distortion, extrapolation of the results to much lower outage probability. Experimental results are presented for both external and direct (chirp) modulation at a 2.5 Gbps data rate over a fiber with polarization dispersion with an average delay of 120 psec for direct detection.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Book Chapter
01 Jan 1993
TL;DR: In this paper, the polarization mode dispersion (PMD) measurements of long standard fibers, dispersion shifted (DS-) and dispersion-flattened (DF-) fibers uncabled on bobbins and in cables installed in the test links Berlin IV (18 km long) and Berlin VI (22.6 km).
Abstract: This paper describes the polarization mode dispersion (PMD) measurements of long standard fibers, dispersion-shifted (DS-) and dispersion-flattened (DF-) fibers uncabled on bobbins and in cables installed in the test links Berlin IV (18 km long) and Berlin VI (22.6 km). The PMD is measured with the aid of the interferometric technique, using a Michelson-interferometer. This method is not restricted to long fibers with low birefringence, it can be used to measuring the PMD and group beatlength of short high-birefringent fibers with a high accuracy. It will be shown that the cabling procedure increases the PMD values considerably, up to one order of magnitude.

Patent
16 Nov 1993
TL;DR: In this article, an optical analog signal obtained such that light having a wavelength λ 1 is intensity-modulated or frequency-modicated with a modulation index m per channel and a chirping amount λs for 100% modulation is transmitted.
Abstract: In this invention, an optical analog signal obtained such that light having a wavelength λ1 is intensity-modulated or frequency-modulated with a modulation index m per channel and a chirping amount λs for 100% modulation is transmitted. An optical element (110) connected to an outlet of a transmission medium having a polarization mode dispersion τ with respect to an optical signal is selected such that when the optical signal output from the optical element requires a predetermined composite second-order distortion C [dB], a transmittance T₀ of the optical element for the light having the wavelength λ1 and a polarization dependency A of an insertion loss satisfy the following condition: 20 log₁₀{ (2πc/λ1² ) · n · (A/T₀ ) · τ · m · λs}≦C (where n is a number of beats occurring in the optical signal and c is the light velocity).

Patent
17 Nov 1993
TL;DR: In this article, an optical analog signal obtained such that light having a wavelength.lambda.1 is intensity-modulated or frequency modulated with a modulation index m per channel and a chirping amount. lambda.s for 100% modulation is transmitted.
Abstract: OF THE DISCLOSURE In this invention, an optical analog signal obtained such that light having a wavelength .lambda.1 is intensity-modulated or frequency-modulated with a modulation index m per channel and a chirping amount .lambda.s for 100% modulation is transmitted. An optical element connected to an outlet of a transmission medium having a polarization mode dispersion ? with respect to an optical signal is selected such that when the optical signal output from the optical element requires a predetermined composite second-order distortion C [dB], a transmittance T0 of the optical element for the light having the wavelength .lambda.1 and a polarization dependency A of an insertion loss satisfy the following condition:20 log10{ (2.pi.c/.lambda.12) ? n ? (A/T0) ? ? ? m ? .lambda.s}?C (where n is a number of beats occurring in the optical signal and c is the light velocity).

Proceedings ArticleDOI
Takashi Ono1, Masao Morie1, Katsumi Emura1
04 Apr 1993
TL;DR: In this article, the authors proposed a principal states transmission (PST) method to avoid the influence of polarization mode dispersion influence on the bit error rate (BER) of EDFAs.
Abstract: Recent investigations regarding long-haul high-speed transmission systems using Er-doped fiber amplifier repeaters have shown a possibility of realizing the systems of up to 10000 km transmission distance [1][2]. In these system, accumulated polarization dependencies, such as polarization mode dispersion (PMD) and polarization depending loss (PDL) in the fiber and EDFAs, induce a fading in bit error rate (BER) characteristic [3]-[5]. Polarization mode dispersion induces inter-symbol-interference (ISI) in IM-DD systems according to input polarization states because of propagation delay time between the two orthogonal eigen modes (principal states). This influence becomes a serious problem by increasing the bit rate or the transmission length. To avoid polarization mode dispersion influence, the authors have been proposed a "principal states transmission method [6]", which launches the signal light at one of principal states. However, the formerly proposed method can not be applied to optical repeater systems, which include optical isolators, because a pilot light is required to transmit in the opposite direction of the signal light in the same fiber.