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.

Corrections to fixed analyzer measurements of polarization mode dispersion

Abstract: We report computer simulation results of polarization mode dispersion (PMD) measurements using the fixed analyzer technique. We find a new value for the polarization mode coupling factor of 0.805 (a 2% difference with the old value of 0.824). Systematic biases due to sampling density and extrema thresholding are quantified (6-12% for typical measurement conditions), and a simple correction algorithm is presented which removes the effects of these biases within /spl plusmn/1.7%.

Impact of Optical Phase Conjugation on the Nonlinear Shannon Limit

Abstract: Compensation of the detrimental impacts of nonlinearity on long-haul wavelength division multiplexed system performance is discussed, and the difference between transmitter, receiver, and in-line compensation analyzed. We demonstrate that ideal compensation of nonlinear noise could result in an increase in the signal-to-noise ratio (measured in dB) of 50%, and that reaches may be more than doubled for higher order modulation formats. The influence of parametric noise amplification is discussed in detail, showing how increased numbers of optical phase conjugators may further increase the received signal-to-noise ratio. Finally, the impact of practical real world system imperfections, such as polarization mode dispersion, are outlined.

Timing recovery in presence of optical impairments and optimization of equalization based on timing recovery moment strengths

Abstract: The present disclosure provides timing recovery in optical systems in the presence of chromatic dispersion (CD), polarization mode dispersion (PMD), and polarization dependent loss (PDL) and to optimization of equalization settings based upon timing recovery moment strengths. A stable timing point may be determined in the presence of PMD and PDL impairments, even when the direct estimate of timing becomes unreliable. This determination may be performed entirely in the digital domain providing precise, predictable performance. Also, the present invention utilizes a monotonic relationship between the timing metric and CD setting error to provide directed search in setting the CD equalizer thereby reducing significantly the overall search effort in optimizing CD equalizer settings. This utilizes computations already performed by the transceiver for timing recovery function yielding a computational advantage over competing methods.

Cyclostationarity-based joint monitoring of symbol-rate, frequency offset, CD and OSNR for Nyquist WDM superchannels.

Abstract: Software-defined transceivers can be reconfigured based on demand and existing channel impairments, and as such, monitoring of both signal and channel parameters is necessary. We demonstrate a novel joint estimation method suitable for spectrally efficient Nyquist wavelength-division multiplexing (WDM), based on the cyclostationary property of linearly modulated signals, exploited both in the frequency and time domains. Using a Nyquist superchannel composed of three 10 GBaud channels, we experimentally demonstrate the simultaneous monitoring of symbol-rate with 100% accuracy, roll-off, frequency offset (FO), chromatic dispersion (CD) and optical signal-to-noise ratio (OSNR) with root-mean-square errors (RMSE) of 20%, 4 MHz, 200 ps/nm and 1.5 dB respectively, when the roll-off factor is larger than 0.06 for DP-QPSK and 0.3 for DP-16QAM.

Apparatus and method for measurement and adaptive control of polarization mode dispersion in optical fiber transmission systems

Abstract: In accordance with the invention, an optical fiber transmission system is provided with a new method and apparatus to measure PMD and then to use the measurements to control adaptive optical filters that minimize system signal degradation. The measurements provide accurate information to compensate for distortions and thereby permit higher transmission rates. The new technique can obtain phase information without optical heterodyning and without bandlimiting. In a first embodiment, an optical signal transmitter, such as a laser/modulator pair, is driven by a data signal combined with a test signal, in the form of a comb of tones with known relative magnitude and phase relationships. Tunable all pass filters recover phase and magnitude information to control an adaptive filter for precise compensation. In a second embodiment, no changes are made to the transmitted signal. The relative delay between orthogonal polarizations of a modulated signal can be obtained by using a polarization beam splitter (PBS), flipping (rotating by 90°) the polarization of one output, sweeping a narrowband optical filter (NBF) across the signal spectrum and detecting the interference between polarizations. Additional detectors can obtain the magnitude versus frequency for the orthogonal components, x and y.