摘要:
推导了多色部分相干偏心光束在non-Kolmogorov湍流中传输的总光强、轴上光谱、相干度的解析表达式，研究了光束偏心参数β、湍流广义指数α和源光谱带宽?对激光传输特性的影响.研究表明：β越大，则光束重心偏离传输轴越远，相干度的不对称性越明显，但是，β对轴上光谱几乎没有影响；湍流广义指数α对总光强、轴上光谱和相干长度的影响是非单调的，当α=3.1时，湍流对光束传输特性的影响最大.值得指出的是：在某些传输距离处，不同α对应的轴上光谱位移量相同；在某些传输距离处，轴上光谱位移量为零，且该传输距离与?无关，但湍流使得该传输距离缩短.所得结论对多色部分相干偏心光束在湍流大气中传输的相关应用具有重要意义.
Abstract:
In this paper, the analytical expressions for the total intensity, the on-axis spectrum and the degree of coherence of polychromatic partially coherent decentred laser beams propagating in non-Kolmogorov turbulence are derived. The influences of the beam decentred parameterβ, the fractal constantαof the atmospheric power spectrum, and the bandwidth? of spectrum on propagation property are studied. It is shown that the larger the value ofβ, the bigger the deviation of centre of beam gravity from the propagation axiis, and the more unsymmetrical the coherence degree is. However, the on-axis spectrum is nearly independent ofβ. The influence ofα on total intensity, on-axis spectrum and coherence degree is non-monotonic. Whenα=3.1, the propagation properties are most affected by turbulence. It is mentioned that at certain propagation distances, the shifts of on-axis spectrum are the same for different values ofα. Furthermore, the on-axis spectral shift disappears at other propagation distances which are independent of?, and these propagation distances decrease due to turbulence. The results obtained in this paper will be useful for the applications of polychromatic partially coherent decentred laser beams propagating in non-Kolmogorov turbulence.
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