Optical Endless Polarization Stabilization at 9 krad/s With FPGA-Based Controller

We demonstrate endless polarization stabilization with a control speed of up to 9 krad/s, over random Poincare sphere trajectories. These are in total >35 Mrad long, are composed in particular of difficult-to-track circles with all radii and orientations, and thereby include all possible worst cases. The maximum polarization mismatch and relative intensity errors are 0.13 rad and 0.43%, respectively. The controller runs on a field-programmable gate array and uses a commercial multistage LiNbO₃ polarization transformer as the control device.     

Individual hemisphericity and maladaptive behaviors.

Individual hemisphericity of 13 nonparanoid schizophrenics, 12 depressives, 20 manic-depressives, 5 schizo-affectives, 25 alcoholics, and 25 Ss with personality disorders (antisocial type) was compared by utilizing the conjugate lateral eye-movement index. In the population of 100 right-handed males, 45% were found with right hemisphericity, 41% with bilaterality, and 14% with left hemisphericity. Right hemisphericity was found associated with nonparanoid schizophrenia, depression, and alcoholism; bilaterality was found to be related to manic-depression, schizo-affective disorder, and antisocial personality. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polarization mode dispersion detected by arrival time measurementof polarization-scrambled light

Polarization mode dispersion (PMD) limits optical fiber capacity. PMD compensators usually minimize the associated eye closure. This measure scales with the square of the differential group delay (DGD) and makes it difficult to detect low DGDs. However, light with a low-speed polarization modulation suffers arrival time variations, in the presence of PMD, that are proportional to the DGD. These are detected by integrating the voltage-controlled oscillator (VCO) input signal of the clock recovery phase-locked loop (PLL). This novel method has been demonstrated for 40 Gb/s nonreturn-to-zero (NRZ) and for 2×40 Gb/s return-to-zero (RZ) polarization division multiplex transmission. PMD detection sensitivities range between 2 ps and 84 fs     

2/spl times/40 Gbit/s RZ-DQPSK transmission with tunable chromatic dispersion compensation in 263 km fibre link

2/spl times/40 Gbit/s RZ-DQPSK transmission over a 263 km fibre link with back-to-back receiver sensitivity of -27.5 dBm and Q factor >20 dB is demonstrated. The experiment demonstrates sufficient resilience against nonlinear phase noise and band limitation in a 40 Gbit/s WDM DEMUX with Q=17.5 dB.     

Crosstalk detection schemes for polarization division multiplextransmission

Polarization division multiplex (PolDM) is a bandwidth-efficient and sensitive modulation format suitable for upgrading bandwidth-limited trunk lines. We show how control signals for polarization demultiplex can be obtained efficiently. For interleaved return-to-zero (RZ) signals, incoherent crosstalk has to be detected and minimized. In other cases, in particular for non-return-to-zero (NRZ) signals, coherent crosstalk senses penalties much better and should be detected instead. NRZ transmission experiments with either scheme are presented at a data rate of 2×10 Gb/s, with endless polarization tracking. Polarization mode dispersion (PMD) tolerance is also assessed     

Tolerance of bandwidth-efficient optical multilevel modulation schemes against polarization mode dispersion

Contents  Optical polarization division multiplex transmission shows a superior sensitivity and a good polarization mode dispersion tolerance compared to other multilevel modulation schemes. Due to its terminal equipment simplicity compared to quaternary intensity modulation this scheme is advantageous for capacity doubling of fiber spans with a given amplification bandwidth. Theory is verified in a 2 × 10 Gbit/s polarization division multiplex transmission system. Received: 25 October 2000     

Some enabling techniques for polarization mode dispersion compensation

Progress toward 40-Gb/s polarization-mode dispersion (PMD) compensation is presented in several areas. A single-waveplate polarization scrambler that generates Stokes' parameters with just three harmonics has been realized. Together with an arrival-time detection scheme, it allows the detection of about 1 ps of PMD within 2.4 /spl mu/s in a 40-Gb/s nonreturn-to-zero transmission setup. A scrambler that operates independent of its input polarization has also been realized. Both scramblers can be shared among a number of wavelength-division-multiplexed (WDM) channels for which PMD is to be detected. Furthermore, an inverse scattering technique has been implemented to determine differential group-delay profiles of an improved distributed PMD compensator in X-cut, Y-propagation LiNbO/sub 3/. In this context, the most common kind of higher order PMD is identified, which typically persists after compensation of first-order PMD. In a fiber link with polarization scrambling, it is shown to be measurable in a most efficient manner by comparing the rising and falling slopes of the detected signal using two oppositely poled one-way rectifiers placed at the output of a differentiator.