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Showing papers on "Polarization mode dispersion published in 1999"


Journal ArticleDOI
TL;DR: In this article, a distributed optical PMD equalizer with one piece of polarization-maintaining fiber twisted by 64 stepper motors has been proposed and tested in transmission systems with bit rates of 10, 20 and 40 Gb/s.
Abstract: Polarization mode dispersion (PMD), especially in "old" fibers, is considered harmful for installation and upgrading of trunk lines. An optical PMD equalizer should have several or many differential group delay (DGD) sections with polarization transformers in between which can endlessly transform any input polarization into a principal state of the following DGD section. The sections must practically have fixed DGDs unless there is only one section. The small-signal baseband transfer function for PMD, higher order PMD, and the necessary number of sections as well as their control by the output signals of an electrical filter bank in the receiver are also discussed in this context. Several PMD equalizers have been realized and successfully tested in transmission systems with bit rates of 10, 20, and 40 Gb/s. The systems operated stably with well-opened eye diagrams for DGDs ranging between 0 and 1.7 bit durations. Best performance is obtained from a distributed PMD equalizer with one piece of polarization-maintaining fiber twisted by 64 stepper motors. The principle can also be realized in LiNbO/sub 3/.

262 citations


Patent
Richard Edward Epworth1
14 Jan 1999
TL;DR: In this paper, the dispersion in an optical signal transmitted through a waveguide of a communications system is compensated by separating the dispersed signal into components corresponding to principal polarization states, which are recombined to provide a dispersion compensated optical output signal.
Abstract: Polarization mode dispersion in an optical signal transmitted through a waveguide of a communications system is compensated by separating the dispersed signal into components corresponding to principal polarization states. The components are delayed by respective delays differing by a delay increment which is controlled to correspond to the dispersion delay and the delayed components are recombined to provide a dispersion compensated optical output signal. Each of the delays is provided by an chirped Bragg reflector forming part of a delay line, the Bragg reflectors comprising optical fibres with chirped intracore index gratings. Transducers or temperature controllers acting on one of the fibres allows dimensional control of the grating periodicity such that the position of Bragg reflection is variable. Wavelength division multiplexed optical signals are compensated using sampled gratings which allow a common Bragg reflection position for each wavelength.

226 citations


Journal ArticleDOI
TL;DR: In this paper, a Muller matrices-based measurement technique was proposed for the determination of second-and higher-order PMD vectors in optical fibers, which requires the launch of only two polarizations per wavelength and uses large rotation angles as well as interleaving.
Abstract: A polarization-mode dispersion (PMD) measurement technique is described that allows the determination of second- and higher order PMD vectors in optical fibers. The algorithm, based on Muller matrices, requires the launch of only two polarizations per wavelength and uses large rotation angles as well as interleaving to attain low-noise high-resolution PMD data. It has been applied to fibers ranging from 2 to 40 ps in mean PMD.

217 citations


Journal ArticleDOI
TL;DR: In this paper, a new method for the measurement of distributed polarization mode dispersion (PMD) in optical fibers is presented, which is based on a measurement of the degree of polarization of the backscattered light as a function of distance in the fiber.
Abstract: This paper presents a new method for the measurement of distributed polarization mode dispersion (PMD) in optical fibers. This method uses a polarization optical time-domain reflectometer (P-OTDR), and is based on a measurement of the degree of polarization of the backscattered light as a function of distance in the fiber. Both the average and the statistics of the degree of polarization are used to estimate the two relevant parameters for measuring PMD, namely, the beat length and the coupling length. At present, our P-OTDR gives qualitative results only. However, it enables to distinguish between high and low PMD sections in a long fiber link. This should already have practical applications, in particular for the characterization of installed fibers.

203 citations


Journal ArticleDOI
TL;DR: It is derived, for what is believed to be the first time, the autocorrelation function (ACF) of the polarization-mode dispersion vector, which gives information on the bandwidths of the principal states of polarization.
Abstract: We derive, for what is believed to be the first time, the autocorrelation function (ACF) of the polarization-mode dispersion (PMD) vector, which gives information on the bandwidths of the principal states of polarization. We compare the ACF with measured data and find good agreement. Finally, we apply the derived ACF to calculate the average pulse broadening that is due to PMD.

179 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a description and detailed uncertainty analysis of a polarization-mode dispersion (PMD) measurement system that uses the Jones matrix eigenanalysis measurement technique based on a rotating-wave-plate Stokes polarimeter.
Abstract: We present a description and detailed uncertainty analysis of a polarization-mode dispersion (PMD) measurement system that uses the Jones matrix eigenanalysis measurement technique based on a rotating-wave-plate Stokes polarimeter. The uncertainty of the system is 3.2 fs (∼95% confidence interval) and is due primarily to PMD in the fiber leads of the measurement system.

136 citations


Journal ArticleDOI
TL;DR: This work describes how to calculate the Jones matrix transfer function of a fiber if its principal states of polarization and its differential group delay as functions of frequency are known and shows that a previous method used for this purpose induces overestimation of second-order PMD effects.
Abstract: We describe how to calculate the Jones matrix transfer function of a fiber if its principal states of polarization and its differential group delay as functions of frequency are known. Using two counterexamples related to second-order polarization mode dispersion (PMD), we also show that a previous method used for the same purpose induces overestimation of second-order PMD effects by a factor of 2. Our new method is used to solve the problem for both counterexamples.

124 citations


Proceedings ArticleDOI
21 Feb 1999
TL;DR: In this paper, a polarization-mode dispersion (PMD) transient recorder setup was realized enabling for the first time to the knowledge the monitoring of fast PMD fluctuation with a bandwidth of up to 1 MHz.
Abstract: A polarization-mode dispersion (PMD) transient recorder setup was realized enabling for the first time to our knowledge the monitoring of fast PMD fluctuation with a bandwidth of up to 1 MHz. Thirty-six hours of observation of an installed field fiber exhibits significant PMD variation within 10 ms.

120 citations


Journal ArticleDOI
TL;DR: In this paper, the authors show that compensation sharpens the probability distribution function of the pulse durations by a factor that decreases with increasing polarization dispersion, and that compensation can be achieved by using principal states of polarization.
Abstract: Polarization mode dispersion in standard telecommunication fibers can be compensated to first order by using the concept of principal states of polarization. At the receiver the pulse is decomposed into the two waveforms polarized along the two principal states for the optical link and their delay is removed. We show by Monte Carlo simulation that compensation sharpens the probability distribution function of the pulse durations by a factor that decreases with increasing polarization dispersion.

109 citations


Journal ArticleDOI
TL;DR: It is shown that multistage designs can achieve a substantial increase in passband width and peak dispersion for a given group-delay ripple compared with single-stage designs.
Abstract: A compact, multichannel dispersion-compensating filter is demonstrated with D=-4200 ps/nm, a +/-5-ps group delay ripple, <3-dB loss, and a 4.5-GHz passband width out of a 12.5-GHz free spectral range. We show that multistage designs can achieve a substantial increase in passband width and peak dispersion for a given group-delay ripple compared with single-stage designs. The dispersion-compensation effectiveness was demonstrated in a 320-km, seven-channel nonlinear system simulation for OC48 signals.

100 citations


Journal ArticleDOI
TL;DR: The polarization properties of concatenations of trunks of birefringent fibers and elements with polarization-dependent losses are analyzed and it is shown both theoretically and experimentally that the concatenation can have zero differential group delay over a whole range of wavelengths but that a pulse propagating down the concattenation can still experience significant pulse spreading.
Abstract: The polarization properties of concatenations of trunks of birefringent fibers and elements with polarization-dependent losses are analyzed We show both theoretically and experimentally that the concatenation can have zero differential group delay over a whole range of wavelengths but that a pulse propagating down the concatenation can still experience significant pulse spreading In this example the two main methods used for characterizing polarization mode dispersion in optical fiber systems, ie, Jones matrix eigenanalysis and the interferometric method, give different results This counterintuitive example underlines the need for a careful assessment of the basic concepts related to polarization effects in the presence of polarization-dependent losses

Patent
08 Apr 1999
TL;DR: In this article, an optical modulator is provided to control the intensity of a transmitted or reflected light, where a separator splits arbitrarily polarized light into two polarization rays and one is made to travel a separate path from the other.
Abstract: An optical modulator is provided to control the intensity of a transmitted or reflected light. In a transmission mode, a separator splits arbitrarily polarized light into two polarization rays and one is made to travel a separate path from the other. A recombiner causes the two rays to recombine at an output unless an electro-optic phase retarder changes the polarization of the two rays, in which case, both of them miss the output by an amount which is a function of the voltage on the retarder. A normally-off version with low polarization mode dispersion is obtained by changing the orientation of the recombiner. A normally-on version with low polarization mode dispersion is obtained with a passive polarization direction rotation. Similar results can be obtained in a reflection mode where the input and output are on the same side of the modulator. Versions using a GRIN lens are particularly suited to modulation of light out of and back into fiber-optic cables. The device can be operated as a variable optical attenuator, an optical switch, or a high speed modulator and is insensitive to polarization of the input light. A preferred material for the phase retarder is a hot-pressed ceramic lead lanthanum zirconate titanate composition.

Journal ArticleDOI
TL;DR: In this paper, the authors present a statistical description of polarization dependent chromatic dispersion in optical fibers due to second-order polarization mode dispersion (PMD), which is the cause of pulse broadening and compression of the signal components propagating in the principal states of polarization.
Abstract: This paper presents a statistical description of polarization dependent chromatic dispersion (PCD) in optical fibers due to second-order polarization mode dispersion (PMD). This chromatic dispersion is the cause of pulse broadening and compression of the signal components propagating in the principal states of polarization. We show here that, remarkably, the probability density function of PCD has the form of the energy density of a first-order optical soliton. We report measurements that are in agreement with the prediction of this soliton density. Moreover, since a large number of independent experimental samples are difficult to obtain, we also report simulations of the experimental process and these serve to underscore the agreement between theory and measurement. The probability density functions of first and second-order PMD vectors are spherically symmetric. However, these vectors are not statistically independent. The mean square depolarization with respect to wavelength of a launched pulse is revealed to be 33% stronger than expected for spherical symmetry in the absence of dependence, while the mean square PCD is weaker by 67%.

Proceedings ArticleDOI
21 Feb 1999
TL;DR: In this article, a simple and simple polarization-mode dispersion compensator based on the dynamic maximization of the degree of polarization is proposed and evaluated at 10 Gbit/s.
Abstract: We experimentally validate at 10 Gbit/s a new and simple polarization-mode dispersion compensator based on the dynamic maximization of the degree of polarization. First-order compensation is demonstrated and ultimate statistical performance is numerically assessed.

Journal ArticleDOI
TL;DR: In this paper, an adjustable polarization-mode-dispersion (PMD) compensator using a nonlinearly chirped fiber Bragg grating written into a high-birefringence photosensitive fiber is presented.
Abstract: We demonstrate an adjustable polarization-mode-dispersion (PMD) compensator. The device uses a nonlinearly chirped fiber Bragg grating written into a high-birefringence photosensitive fiber. By mechanically stretching the grating, the device generates a time delay between different polarizations that is adjustable from 100 to 320 ps and is tunable over 2.3 nm. We demonstrate tunable PMD compensation of a 10-Gb/s signal that has an initial delay between the two polarization states of 127 or 302 ps.

Journal ArticleDOI
TL;DR: In this paper, a nonlinearly chirped fiber Bragg grating is used to provide a dispersive function that can be varied continuously by tuning a single mechanical stretching element.
Abstract: Several channel-degrading effects are present in nonstatic and dynamically reconfigurable wavelength-division-multiplexed systems and networks due to various types of dispersion in the optical transmission fiber. These effects must be addressed by tunable methods so that data signals do not fade with time. The relevant effects for which we demonstrate tunable compensation include: chromatic dispersion accumulated in a single channel and in multiple channels, polarization mode dispersion, and periodic RF power fading. We utilize a nonlinearly chirped fiber Bragg grating that provides a dispersive function that can be varied continuously by tuning a single mechanical stretching element.

Patent
22 Dec 1999
TL;DR: In this paper, a polarization controller (PC) receives a dithering optical signal including first and second principal states of polarization (PSPs) and PMD distortion received by the PMD compensator.
Abstract: A polarization mode dispersion (PMD) compensator (10) compensates for PMD in an optical signal by an automatic tracking of a principal state of polarization (PSP). A polarization controller (PC)(22) receives a dithering optical signal including first and second principal states of polarization (PSPs) and PMD distortion received by the PMD compensator. The PC transforms the first and second PSPs into linearly polarized components, and is responsive to a feedback control signal for aligning the lenearly polarized first and second PSPs to first and second polarization axes of the PBS, respectively. A polarization beam splitter (PBS) (24) directs first polarized components of the received dithering optical signal onto a first output path, and directs second orthogonally polarized components of the received dithering optical signal onto a second output path for transmission as a PMD compensator output signal.

Journal ArticleDOI
TL;DR: In this paper, the stability and resolution of this technique was shown to be below 0.2 fs and the precision was improved by reducing the length of the down-conversion crystal and increasing the spectral band pass of the system.
Abstract: system. The stability and resolution of this technique is shown to be below 0.2 fs. We explore how this precision is improved by reducing the length of the down-conversion crystal and increasing the spectral band pass of the system.

Journal ArticleDOI
TL;DR: In this article, the authors apply multiple-length-scale methods to the study of optical-fiber transmission because the key length scales span 13 orders of magnitude and cluster in three main groups.
Abstract: It is natural to apply multiple-length-scale methods to the study of optical-fiber transmission because the key length scales span 13 orders of magnitude and cluster in three main groups. At the lowest scale, corresponding to micrometers, the full set of Maxwell's equations should be used. At the intermediate scale, corresponding to the range from one centimeter to tens of meters, the coupled nonlinear Schrodinger equation should be used. Finally, at the longest length scale, corresponding to the range from tens to thousands of kilometers, the Manakov-PMD equation should be used, and, when polarization mode dispersion can be neglected and the fiber gain and loss can be averaged out, one arrives at the scalar nonlinear Schrodinger equation. As an illustrative example of multiple-scale-length techniques, the nonlinear Schrodinger equation will be derived, carefully taking into account the actual length scales that are important in optical-fiber transmission.

Journal ArticleDOI
TL;DR: In this paper, the evolution of the degree of polarization of individual channels and their Stokes parameters in a wavelength division multiplexed (WDM) system in which Kerr nonlinearity and chromatic dispersion are taken into account but in which polarization mode dispersion as well as polarization dependent loss and gain are neglected.
Abstract: This paper numerically investigated the evolution of the degree of polarization of individual channels and their Stokes parameters in a wavelength division multiplexed (WDM) system in which Kerr nonlinearity and chromatic dispersion are taken into account but in which polarization mode dispersion as well as polarization-dependent loss and gain are neglected. We compared the results to a mean field model which assumes that the channels are strongly dispersion-managed so that each channel is only affected by the Stokes parameters of the others. This model predicts no change in the degree of polarization of each of the channels so that an initially polarization-scrambled channel does not repolarize. The full simulations showed that the repolarization of a polarization-scrambled signal is small for parameters corresponding to realistic communication systems, validating the use of the mean field model. However, we also found that the repolarization can become significant for low data rates and a small number of channels in a dispersion-managed system with a short length map, thus setting limits on the model's validity and indicating operating regimes that should be avoided in real communication systems.

Patent
22 Dec 1999
TL;DR: In this article, a high order polarization mode dispersion (PMD) compensation arrangement was proposed to compensate for PMD in an optical signal using a temporal imaging technique, where the phase of the first and second polarization components associated with each data bit were delayed by a predetermined amount.
Abstract: A high order polarization mode dispersion (PMD) compensation arrangement (10) compensates for PMD in an optical signal using a temporal imaging technique. An optical data input signal to the PMD compensator arrangement includes first and second polarization components for each bit of data that have been subjected to PMD. In the PMD compensation arrangement (10) a clock recovery arrangement (30) generates an electrical clock output control signal including a predetermined phase modulation depth and phase and a data rate of the received optical input data signal. A phase modulator (26) is responsive to the optical input data signal and the electrical clock output control signal from the clock recovery arrangement (30) for generating an optical output signal. In this optical output signal, the phase of the first and second polarization components associated with each data bit are delayed by a predetermined amount. A dispersive unit (28) introduces a predetermined amount of dispersion to the first and second polarization components in the optical output signal from the phase modulator (26) for generating an output optical signal from the PMD compensation arrangement (10) wherein the first and second polarization components for each data bit are in phase.

Journal ArticleDOI
TL;DR: In this paper, the impact of the dispersion map on the transmission performance was experimentally investigated and the improvement of transmission performance by the polarization division multiplexing, which reduced soliton-soliton interaction, was also confirmed.
Abstract: Forty Gb/s single-channel soliton transmission experiments using periodic dispersion compensation were conducted. The impact of the dispersion map on the transmission performance was experimentally investigated. The transmission performance was significantly varied with the dispersion map. The improvement of the transmission performance by the polarization division multiplexing, which reduced soliton-soliton interaction furthermore, was also confirmed. By using the polarization division multiplexing in the optimum dispersion map, 40 Gb/s single-channel transmission over 10200 km has been successfully demonstrated without any active inline transmission control.

Proceedings ArticleDOI
Henning Bulow1
21 Feb 1999
TL;DR: In this paper, a new theoretical model exhibits that first-order polarization-mode dispersion (PMD) compensation extends the maximum acceptable PMD to 0.35 times the bit period T.
Abstract: A new theoretical model exhibits that first-order polarization-mode dispersion (PMD) compensation extends the maximum acceptable PMD to 0.35 times the bit period T. At 10 gbit/s chromatic dispersion of 850 ps/nm (50 km SMF) reduces this PMD limit to 0.29 T.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrated essentially complete dispersion compensation for 400-fs pulses over a 10-km fiber link using dispersion compensating fiber and a programmable femtosecond pulse shaper functioning as a spectral phase equalizer.
Abstract: We have demonstrated essentially complete dispersion compensation for 400-fs pulses over a 10-km fiber link using dispersion compensating fiber and a programmable femtosecond pulse shaper functioning as a spectral phase equalizer. The pulse shaper impresses adjustable quadratic and cubic phases onto the spectrum and removes all the residual dispersion and dispersion slope in the dispersion compensated fiber link. Our work shows that the pulse shaper technique provides a powerful and convenient tool for programmable fiber dispersion compensation over broad optical bandwidth. This allows distortion-free femtosecond pulse transmission over a fiber link in excess of 10 km without requiring the exact trimming of the dispersion-compensating fiber.

Journal ArticleDOI
TL;DR: In this article, the second-order polarization-mode-dispersion (PMD) depolarization and related parameters were measured using the Muller matrix method and found that the depolarisation scales with the mean differential group delay (DGD) and chromatic dispersion with the square of the mean DGD.
Abstract: The Muller matrix method enables the low-noise, high-resolution measurement of second-order polarization-mode-dispersion (PMD) depolarization and related parameters required for systems modeling. We report experimental observations of second-order PMD statistical dependencies and scaling for fibers with mean differential group delay (DGD) ranging from 1.3 to 17.0 ps. Measurements of 10 different fibers confirm that the depolarization scales with the mean DGD while the polarization-dependent chromatic dispersion scales with the square of the mean DGD.

Proceedings ArticleDOI
21 Feb 1999
TL;DR: In this paper, the authors measured optically preamplified receiver sensitivity after distortion by polarization-made dispersion (PMD) and found that RZ modulation was more resilient to PMD than NRZ modulation.
Abstract: Using 10-Gbit/s signals, amplitude modulated with either a return-to-zero (RZ) or a nonreturn-to-zero format (NRZ), we measured optically preamplified receiver sensitivity after distortion by polarization-made dispersion (PMD). RZ modulation was found to be more resilient to PMD than NRZ modulation.

Journal Article
TL;DR: A description and detailed uncertainty analysis of a polarization-mode dispersion measurement system that uses the Jones matrix eigenanalysis measurement technique based on a rotating-wave-plate Stokes polarimeter is presented.
Abstract: We present a description and detailed uncertainty analysis of a polarization-mode dispersion (PMD) measurement system that uses the Jones matrix eigenanalysis measurement technique based on a rotating-wave-plate Stokes polarimeter. The uncertainty of the system is 3.2 fs (∼95% confidence interval) and is due primarily to PMD in the fiber leads of the measurement system.

Patent
24 Sep 1999
TL;DR: In this paper, a polarization mode dispersion (PMD) emulator may include one or more modular cells that emulate PMD, with each of the cells including optical delay and phase modulation components.
Abstract: A polarization mode dispersion (PMD) emulator may include one or more modular “cells” that emulate PMD Each of the cells may include optical delay and phase modulation components The optical delay and/or the phase modulation components may be adjusted to account for differences in PMD and two or more of the cells may be combined to further adjust the overall PMD of the apparatus Similarly, a PMD compensator may include one or more modular “cells” that compensate for PMD, with each of the cells including optical delay and phase modulation components The optical delay and/or the phase modulation components may be adjusted to compensate for various PMD values and two or more of the cells may be combined to further adjust the overall PMD compensation of the apparatus The PMD compensator apparatus may be used to compensate for PMD in wideband applications, such as wavelength division multiplexed (WDM) systems

Journal ArticleDOI
TL;DR: In this paper, the authors compared compression characteristics at femtosecond durations for dispersion-decreasing fibers (DDF's) constructed out of standard step index fibers and fibers designed to have low third-order dispersion (dispersion-flattened fibers).
Abstract: The compression characteristics at femtosecond durations are compared for dispersion-decreasing fibers (DDF's) constructed out of standard step index fibers and fibers designed to have low third-order dispersion (dispersion-flattened fibers). It is shown that the dispersion slope of a standard fiber causes the compressed pulse spectrum to vary substantially with wavelength. Furthermore, the peak of the compressed pulse spectrum can appear in a different wavelength band than the input pulse. Both of these problems are substantially reduced by using a dispersion-flattened DDF. The compression of 3-3.6-ps pulses to durations less than 180 fs was achieved between 1533-1565 nm at a repetition rate of 10 GHz. The shortest pulses obtained were 98 fs with peak-to-pedestal ratios in excess of 20 dB.

Patent
Yanming Liu1
17 Feb 1999
TL;DR: In this paper, a single mode optical waveguide fiber having alternating segments of positive and negative dispersion and dispersion slope is described, and the relative indexes, the refractive index profiles and the radii of the segments are chosen to provide low total dispersion.
Abstract: Disclosed is a single mode optical waveguide fiber having alternating segments of positive and negative dispersion and dispersion slope. The relative indexes, the refractive index profiles and the radii of the segments are chosen to provide low total dispersion and dispersion slope. One embodiment consists of a first central major index profile (10) of outer radius r1, surrounded by a first annular segment (12) of outer radius r2, surrounded by second annular segment (14) of outer radius r3. Preferred waveguides in accordance with the invention exhibit a dispersion over the range of 1520 to 1625 nm which at all times have a magnitude which is less than 2, and more preferably less than 1 ps/nm2-km. The total dispersion of the waveguide fiber is in the range of about -2.0 to +2.0 ps/nm-km at 1550 nm. The waveguide also features a low polarization mode dispersion.