Raman-enhanced polarization beats in Markovian stochastic fields
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文摘
Raman-enhanced polarization beats (REPBs) with broadband noisy light are investigated using chaotic field, phase-diffusion, and Gaussian-amplitude models. The polarization beat signal is shown to be particularly sensitive to the statistical properties of the Markovian stochastic light fields with arbitrary bandwidth. Different stochastic models of the laser field only affect the sixth- and fourth-order coherence functions. The interferometric contrast ratio is equally sensitive to the amplitude and phase fluctuations of the Markovian stochastic fields. The constant background of the beat signal originates from the amplitude fluctuation. The Gaussian-amplitude field shows fluctuations larger than the chaotic field, which again exhibits fluctuations much larger than for the phase-diffusion field with pure phase fluctuations caused by spontaneous emission. It is also found that the beat signal oscillates not only temporally but also spatially, and the temporal period corresponds to the Raman frequency shift of 655.7cm−1. The overall accuracy of using REPB to measure the Raman resonant frequency is determined by the relaxation rates of the Raman mode and the molecular-reorientational grating. It is worth mentioning that the asymmetric behaviors of the polarization beat signals due to the unbalanced dispersion effects between two arms of interferometer do not affect the overall accuracy in case using REPB to measure the Raman resonant frequency, and different colors are optimally correlated at different values of the interferometric delay.