Lorinda Wu

Statistical characterization of the output state of polarization in deployed single-mode fibers

Changes in the optical fiber properties due to both intrinsic and extrinsic variations result in polarization mode dispersion and state of polarization (SOP) becoming stochastic in nature. The statistics for first-order PMD and the second-order PMD approach the Maxwellian and Foschini et al. [IEEE Photonics Technol. Lett.12, 293 (2000)] distributions, respectively. In this Letter, we investigate a theoretical statistical distribution that corresponds to output SOP variations. The SOP variations can either be with wavelength (for buried fiber) or with time (for aerial fiber). Our results show that the statistics of the relative SOP changes approach the distribution proposed by Foschini et al..

Polarization mode dispersion emulation using polarization maintaining fibers: Fixed root-mean-square differential group delay but varying second-order polarization mode dispersion

We report on a polarization mode dispersion (PMD) emulator with a fixed root-mean-square differential group delay (RMS-DGD) but varying second-order PMD (SO-PMD) using only a combination of polarization maintaining fibers and a polarization controller. The SO-PMD control mechanism is not completely in real time. Besides controlling the mean PMD values of the emulator, simultaneous adjustments in the maximum and minimum values of PMD statistics can be performed. We therefore illustrate irregular fluctuations that occur around the RMS-DGD due to SO-PMD. This novel design can be used to further show the impact of a high first-order PMD segment on the DGD and SO-PMD statistical distributions that might occur in an optical network system.

Insight into PMD Regimes: An Analysis on Buried Optical Fibres

Polarization mode dispersion (PMD) field measurements on deployed buried fibres showed that the PMD variation over the 1520 to 1570 nm wavelength was stochastic. The PMD variation over the 98-hour period for each wavelength was directional and limited; they are due to the presence of random mode coupling along the fibre length and limited influence from extrinsic perturbations over time, respectively. PMD variation in the wavelength domain showed that the mean first-order PMD (FO-PMD) value is independent of whether the FO-PMD statistics of a fibre link approaches the Maxwellian theoretical distribution; the key factor is sufficient random mode coupling. The accompanying second-order PMD (SO-PMD) statistics, with FO-PMD statistics approaching Maxwellian, followed the PDF given by Foschini et al. (1999). The FO- and SO-PMD statistics at a given wavelength gave nonstochastic PMD distributions with time.

Statistical characterization of first-order and second-order polarization mode dispersion in a deployed buried optical fibre cable

Polarization mode dispersion (PMD) is a major impediment towards high speed data transmission in optical network systems. In order to plan and budget for network outages, an accurate analysis of PMD measurements is required. In this paper we experimentally characterize a deployed buried cable for both first and second-order polarization mode dispersion, and evaluate the statistical nature of first-order PMD using the Np/W-ratio together with the known p-value. Results show that the p-value and Np/W-ratio are opposite in behaviour in the presence of random mode coupling.

The General interferometry technique: Interferogram analysis in the presence of a high polarization mode dispersion segment

The General interferometry technique (GINTY) is used to measure the mean PMD of an entire fibre link. In this paper, we analyse the GINTY interferogram envelopes in the presence of an adjustable high polarization mode dispersion (HiPMD) segment. Experimental results show that the GINTY interferogram will develop two symmetric satellite interferogram envelopes and one central interferogram envelope in the presence of a HiPMD segment. Further increases in the PMD of the HiPMD segment results in the two satellite envelopes drifting in opposite directions by an equal amount whilst the central envelope remains fixed in position. Therefore GINTY can be used to detect the presence of a HiPMD segment, although unlike the polarization-optical time domain reflectometry technique (P-OTDR) it cannot give the exact location of the HiPMD segment.

The impact of a high differential group delay section on the output state of polarization of propagating light

Research to date has shown that high differential group delay (HiDGD) sections along an optical fiber network link are the major contributors to PMD. PMD has deleterious effects on propagating optical signals. In this paper, we show the effect a HiDGD section has on the output state of polarization (SOP) of propagating light. Experimental results in this paper show a reduction in the range of the output SOP spread with an increase in the DGD of the HiDGD section to a given asymptote (a minimum) i.e. when HiDGD ≥ 35ps. However, the output SOP spread and its asymptote solely depends on the location of the HiDGD section along the fiber link length. A small output SOP spread over the entire wavelength scan covers a few polarization states on the Poincaré sphere and vice versa for a large output SOP spread. The small output SOP spread over the entire wavelength range (50 nm in steps of 0.3 nm for this study) is an indicator that the polarization capabilities of optical telecommunication signals are restricted to minute SOPs.

A Fixed Differential Group Delay but Varying Second-Order Polarization Mode Dispersion Emulator

We design a polarization mode dispersion (PMD) emulator with a fixed root-mean-square differential group delay (RMS-DGD) but varying second-order PMD (SOPMD) using only a combination of polarization maintaining fibres and a polarization controller. Besides controlling the mean PMD values of the emulator, simultaneous adjustments in the maximum and minimum values of PMD statistics can be performed. Therefore this novel design will achieve more realistic statistical distribution by exhibiting irregular fluctuations that occur around the RMS-DGD due to SOPMD.