光学外差探测信噪比研究

对于光学外差探测系统而言,为了有效利用回波信号,需要对信噪比这一表征系统性能的重要指标进行研究。从理论分析了信噪比,给出了计算信噪比的一般公式。理论分析表明,当探测器光敏面上本振光与信号光的振幅、相位、偏振都满足严格的匹配时,外差效率最大。对场分布为艾里函数的光外差信噪比进行研究和数值模拟。结果表明,当艾里斑尺寸的比例系数控制在0.8~1.2内,并使信号光斑主轴偏移量x0控制在0.5以下,探测器的尺寸在(0.6~0.8)λf/d内时,可获得大于0.7ηPs/hνB的信噪比。

Signal-Noise Ratio in Optical Heterodyne Detection

Signal-noise ratio (SNR) is an important parameter for the performance of a heterodyne detection system. In order to make full use of the received signal, the signal-noise ratio should be analyzed.The principle of signal-noise ratio is discussed, and general equations for a shot noise limited operation are derived in terms of the distribution functions of the local oscillator and signal fields, the size and quantum efficiency of the detector. To obtain the maximum signal-noise ratio, the phase, amplitude and polarization of the local oscillator and the signal light should be matched strictly. Finally, the signal-noise ratio is discussed for Airy function distribution fields. Numerical simulations show that when the ratio of the size for Airy disks is controlled within 0.8～1.2, the bias x0 of Airy disk axis below 0.5, the size of detector in the range (0.6～0.8)λf/d, the signal-noise ratio is above 0.7ηPs/(hνB).