Polarization mode dispersion

About: Polarization mode dispersion is a research topic. Over the lifetime, 5147 publications have been published within this topic receiving 80055 citations. The topic is also known as: PMD.

Method and apparatus to compensate for polarization mode dispersion

Abstract: A polarization scrambler and a polarization mode dispersion (PMD) compensation system compensate for PMD on an active optic fiber. The polarization scrambler scrambles a state of polarization of an optical signal that carries user information. The PMD compensation system then receives the optical signal over the active optic fiber. The PMD compensation system measuring a differential group delay and principal states of polarization of the PMD in the active optic fiber. The PMD compensation system then determines a modification of the optical signal based on the differential group delay and the principal states of polarization of the PMD. The PMD compensation system modifies the optical signal in the active optic fiber to compensate for PMD based on the determination of the modification. The PMD compensation system then transmits the optical signal. By measuring the differential group delay and the principal states of polarization, the PMD compensation system adapts to changes in the PMD in the active optic fiber.

Planar lightwave circuit polarization mode dispersion compensator

Abstract: We fabricated an integrated-type optical PMD compensator on a silica-based planar lightwave circuit, where an endless polarization controller and a polarization-dependent delay line are installed. We confirmed its operational principle in a 43-Gbps transmission system.

Efficient Modulation Formats for High Bit-Rate Fiber Transmission

Abstract: The topic of this report will deal with the study of advanced modulation formats for highspeed optical communication systems. Basically, the use of alternate polarization modulation (alP) is considered in order to reduce the inter-symbol interference (ISI) caused mainly by effects such as Chromatic Dispersion (CD), Polarization Mode Dispersion (PMD) and Nonlinear effects. The comparative analysis among the different formats is carried out by means of the obtaining of its different spectrums. A detailed analysis of these and their dependency to the modulation format that generates it is presented. The article presents numerical comparative analysis using commercial software VPI Maker Transmission, where the results obtained show that the formats of alternating polarization are the best results at the bit rate of 40 Gb/s per channel.

Optical equalization of polarization dispersion

Abstract: In this paper, we describe a demonstration of the optical equalization of polarization dispersion in direct-detection lightwave systems. We use a polarization controller to adjust the polarization into a fiber to one of the principal states of polarization of the fiber, which eliminates first-order polarization dispersion. Results for a 2.5 Gbps, externally modulated system with a fiber with 120 ps rms of polarization dispersion, show that by using the equalizer we maintain a 10-9 BER, while without the technique the BER varies with time from 10-5 to 10-9. At 10 Gbps, the equalizer allows reliable bit detection even though the eye is closed without equalization, demonstrating an order of magnitude increase in the dispersion-limited B2L product, in agreement with our analytical and computer simulation results. We also describe a demonstration of the technique at the receiver, and show how to implement an adaptive polarization controller to continuously track the principal states using a gradient search algorithm. This technique provides bit-rate-independent equalization of first-order polarization dispersion.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

All-Digital Timing Recovery and Adaptive Equalization for 112 Gbit∕s POLMUX-NRZ-DQPSK Optical Coherent Receivers

Abstract: An all-digital timing recovery loop is employed in optical coherent receivers, which depends on the number-controlled oscillator and the interpolator to complete timing adjustment in an all-digital way instead of the traditional hybrid way using an analog device (a voltage-controlled oscillator) to adjust the sampling frequency. Therefore it avoids introducing the nonideal characteristics of an analog device and is beneficial to all-digital implementation of optical coherent receivers. Furthermore, in order to meet the requirements of low complexity and sampling rate, the Gardner timing error detector is adopted in the all-digital timing recovery loop. However, it has low tolerance of dispersion, which requires another device to compensate the large residual dispersion prior to it. Although the adaptive equalizer can compensate signal for dispersion impairment, its effective operation must rely upon synchronized signals. For solving the incompatible problem without any extra cost, a joint scheme that embeds an adaptive equalizer into the all-digital timing recovery loop is proposed to accomplish synchronization and compensation of linear transmission impairments. Finally, the feasibility and effectiveness of the proposed scheme are demonstrated in a 112 Gbit/s polarization-multiplexing non-return-to-zero differential-quadrature phase-shift-keying (POLMUX-NRZ-DQPSK) optical coherent receiver by simulation.