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Differential group delay

About: Differential group delay is a research topic. Over the lifetime, 711 publications have been published within this topic receiving 8497 citations.


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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

Journal ArticleDOI
TL;DR: In this article, a simple relationship for the evolution of the principal states of polarization (PSPs) and their differential group delay in fiber links is found, using the relationship, for the probability of DGD.
Abstract: A simple relationship is found for the evolution of the principal states of polarization (PSPs) and their differential group delay in fiber links. A simple expression is found, using the relationship, for the probability of the differential group delay (DGD), considering the evolution of the PSPs as a Brownian motion. The theory has been verified experimentally on an optical cable composed of 12 single-mode, shifted-dispersion fibers 2.2-km long. The results show that the DGD grows as the square root of the length when the length of the fiber is far larger than the correlation length of the perturbation. The measured value of DGD can vary substantially in two fibers belonging to the same ensemble, and in the same fiber, considering two frequencies differing by more than 5 nm. >

196 citations

Proceedings ArticleDOI
20 Dec 2004
TL;DR: In this article, a novel ultrahigh-speed electro-optic polarization modulator is introduced, which uses a mode converter and a static polarization controller to change the output polarization state in a circular path, following a great circle, around the Poincare sphere.
Abstract: A novel ultrahigh-speed electro-optic polarization modulator is introduced. The modulator uses a mode converter and a static polarization controller to change the output polarization state in a circular path, following a great circle, around the Poincare sphere. Any two states on the Poincare sphere can be connected. The mode converter is constructed using an AlGaAs ridge waveguide combined with slow-wave travelling wave electrodes. The travelling wave electrodes are designed to match the velocity of the electrical modulating signal, the data signal, to the optical carrier signal over a broad frequency range. This modulator demonstrates a 3 dB bandwidth in excess of 40 GHz. The polarization modulator exhibits extremely low differential group delay, on the order of a few 10s of femto-seconds, and low drive voltage, on the order of 5 V.

180 citations

Journal ArticleDOI
TL;DR: The proposed measurement technique is based on a polarization-sensitive analysis of the backscattered signal and allows one to calculate the correlation length of the random birefringence affecting the fiber.
Abstract: Experimental results of measurement of the beat length and the differential group delay of several types of long single-mode fiber are presented. The proposed measurement technique is based on a polarization-sensitive analysis of the backscattered signal and allows one to calculate the correlation length of the random birefringence affecting the fiber.

152 citations

Proceedings ArticleDOI
04 Mar 2012
TL;DR: In this article, a transmission fiber for mode division multiplexing supporting LP 01 and LP 11 modes, with low differential group delay, low mode coupling and low loss for both modes, is presented.
Abstract: A transmission fiber for mode division multiplexing supporting LP 01 and LP 11 modes, with low differential group delay, low mode coupling and low loss for both modes is presented. S2 imaging is used for characterization.

137 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20236
202210
20218
202011
20197
201812