功率谱曲线的半高宽是谐振法测量光学谐振腔腔体损耗的重要参数之一。针对测量的电压曲线存在噪声大、纹波大、波形失真严重等问题,采用扫频激光作为入射光源,利用Labview软件编程对实验数据进行曲线拟合,有效地去除了测量噪声,使电压曲线的半高宽具有较好的重复性。最后按照一定的算法将其转换为功率谱曲线的半高宽, 从而计算出被测腔体的损耗。在不增加硬件成本的基础上提高了测量精度。

The Full Width at Half Maximum(FWHM)of the power spectrum curve is one of the most important parameters of the resonance method for measuring the loss of optical resonant cavity. But in the measured voltage curve, there are such problems as serious noise, big ripple, and serious waveform distortion. In this paper, frequency-sweeping laser was adopted as the incident light source, and the Labview software was used to process fitting analysis on the experimental data. The measurement noise is eliminated effectively and the FWHM of the voltage curve after experiments possesses good repeatability, which can be transformed into the FWHM of the power spectrum curve by a certain mathematical algorithm so that the loss of the tested cavity can be calculated. The measurement accuracy is enhanced without increasing hardware cost.