基于自外差结构的窄线宽激光器频率漂移及噪声测试

Frequency drift and noise measurement of narrow line-width laser based on self-heterodyne structure

窄线宽激光器在光学传感领域取得广泛应用,激光器的频率漂移和噪声大小直接影响光学传感器测量精度,采用自外差拍频方法对窄线宽光纤激光器和半导体激光器的频率漂移和噪声特性进行了初步测量。进行了频率漂移测量理论计算,仿真分析了延时光纤长度与频率漂移大小对应关系,确立了延时外差光纤长度;搭建了基于自外差结构的窄线宽激光器频率漂移测试装置,对测试装置组成进行了叙述;基于该测试装置进行了窄线宽激光器的频率漂移和噪声测试,测试表明光纤激光器和半导体激光器均存在明显的频率漂移,漂移速度大约2MHz/10s,光纤激光器的频率噪声要明显低于半导体激光器,与两型激光器的频率噪声测试结果吻合,提出的激光器频率漂移和噪声测试装置,为激光器频率漂移和噪声优选对比提供了一种方便、快捷的测试方法。

Narrow line-width lasers were widely used in optical sensing. The frequency drift and noise of lasers directly affect the measurement accuracy of optical sensors. The frequency drift and noise characteristics of narrow line-width fiber lasers and semiconductor lasers were measured by self-timed optical fiber delay method. Firstly, the theoretical calculation of frequency drift measurement was carried out. The relationship between the length of delay fiber and frequency drift was simulated and analyzed, and the length of delay heterodyne fiber was established. Then, a frequency drift test device for narrow line-width laser based on self-heterodyne structure was built, and the composition of the test device was described. Finally, the frequency drift and noise test of narrow line-width laser was carried out based on the test device. The test results show that there is obvious frequency drift in both fiber laser and semiconductor laser. The drift speed is about 2 MHz/10 s, and the frequency noise of the fiber laser is also lower than that of the semiconductor laser, which is consistent with the measurement results of the frequency noise of the two types of lasers.