Numerical generation of laser-resonance phase noise for optical communication simulators.

We generate random numerical waveforms that mimic laser phase noise incorporating laser-resonance enhanced phase noise. The phase noise waveforms are employed in system simulators to estimate the resulting bit error rate penalties for differential quadrature phase shift keying signals. The results show that baudrate dependence of the bit error rate performance arises from laser-resonance phase noise.

Simple analytical model for low-frequency frequency-modulation noise of monolithic tunable lasers.

We employ simple analytical models to construct the entire frequency-modulation (FM)-noise spectrum of tunable semiconductor lasers. Many contributions to the laser FM noise can be clearly identified from the FM-noise spectrum, such as standard Weiner FM noise incorporating laser relaxation oscillation, excess FM noise due to thermal fluctuations, and carrier-induced refractive index fluctuations from stochastic carrier generation in the passive tuning sections. The contribution of the latter effect is identified by noting a correlation between part of the FM-noise spectrum with the FM-modulation response of the passive sections.

Effects of phase noise of monolithic tunable laser on coherent communication systems.

We investigate the effects of different phase noise processes of SGDBR laser on coherent systems. The SGDBR device operated well with QPSK modulation at 5 Gbaud, while the performance of 16-QAM was significantly degraded due to excess noise. The white FM noise mainly defines the ultimate performance of coherent reception, but the low frequency excess noise can potentially degrade the performance of systems that employ 16-QAM format at 5 Gbaud.

Novel coherent self-heterodyne receiver based on phase modulation detection.

We propose a novel coherent self-heterodyne receiver structure based on phase modulation detection that potentially simplifies the front-end of a coherent optical receiver. The scheme has been demonstrated via simulations and experimentally for a 10 Gb/s DQPSK transmission system.

Orthostatic panic attacks among Vietnamese refugees.

Viewed historically and cross-culturally, orthostatic-induced dizziness, i.e., dizziness caused by standing up from a sitting or a lying position, forms a key aspect of many syndromes: irritable heart (American Civil War), effort syndrome (World War I and World War II), chronic fatigue syndrome (contemporary USA), Gulf War syndrome (contemporary USA), and orthostatic dysregulation (contemporary Japan).

Orthostatic panic as a key Vietnamese reaction to traumatic events: the case of September 11, 2001.

This article discusses a culturally specific response to traumatic events: orthostatic panic attacks among Vietnamese refugees. We compared the rate and severity of orthostatic panic as well as the rates and severity of associated flashbacks a month before and a month after September 11, 2001. After that date, the rate and severity of orthostatic panic greatly increased, as did the rate and severity of associated flashbacks.