频谱仪快速测定窄线宽激光器线宽

针对传统光谱仪和F-P 干涉仪分辨率不能满足窄线宽激光器线宽的测量要求, 基于延时自外差法搭建测试平台.设置频谱分析仪分辨率参数抑制噪声实验, 通过使用20 km 延时光纤、80 MHz声光移频器和50:50 光纤耦合器, 通过光电探测器实现光电转换并利用频谱分析仪分析测试信号.对频谱分析仪分辨带宽RBW 和视觉带宽VBW 以及扫频范围(Scan Range)进行优化设置, 在不降低测试灵敏度的情况下, 将重叠信号分辨开, 使其不会过多滤掉高频成分而失真并对线宽功率谱峰值进行洛伦兹曲线拟合.最后得到了1 550 nm 波长可调谐光纤激光器(1 520~1 570 nm)的线宽值约为161 kHz, 为频谱仪的参数优化设置及窄线宽激光器线宽标定提供了相关参考.

Linewidth rapid measurement of narrow fiber laser by spectrum analyzer

For the linewidth measurement of the narrow linewidth laser, the resolution of the traditional spectrometer and the F-P interferometer is obviously insufficient to meet the requirement of linewidth measurement. In the experiment, a test platform was built using a spectrum analyzer based on the delay self-heterodyne method. Opportune parameters of the spectrum analyzer was set to distinguish noise suppression, using 20 km delay optical fiber based on the result of the calculation, 80 MHz acousto-optic frequency shifter(AOM)and 50:50 fiber coupler, achieve the photoelectric conversion by the photodetector.Optimally set the visual bandwidth(RBW), resolution bandwidth(VBW) and the scan range. Without reducing the testing sensitivity, the analyzer will distinguish overlapping signals and do not filter out too much high frequency to be distorted. Lorenz curve fitting was carried to the linewidth power spectrum peaks. Then it is achieved that the linewidth of the tunable wavelength fiber laser (1520-1570 nm) is about 161 kHz. It provides a reference to optimize the spectrumanalyzer parameter settings and calibrate the linewidth parameter of the narrow linewidth fiber laser.