延迟自外差锁相控制的激光线性扫频技术及其应用

Laser Linear Sweep Frequency Technique Based on Delay Self-Heterodyne Optical Phase Locking and Its Application

光频域反射技术(OFDR)是高空间分辨率和高精度光纤链路性能检测和分布式光纤传感的重要技术途径。其中,激光在宽范围扫频下的扫频非线性和相频噪声是有待解决的关键问题。报道了基于延迟自外差光锁相的激光扫频非线性和相频噪声控制方法,实现了扫频范围为8 GHz、扫频速度为160 GHz/s的低相频噪声高线性激光扫频。基于该扫频激光进行了光纤链路损耗测量和分布式光纤应变传感实验,实现了动态范围为27 dB、空间分辨率为4.3 cm的240 km光纤链路损耗测量以及空间分辨率为5 cm的分布式光纤应变传感。实验验证了锁相控制激光扫频误差的有效性和优越性。

Optical frequency domain reflectometry(OFDR), featuring high spatial resolution and precision, has been regarded as an important technique in the monitoring and diagnosis of fiber-optic links and networks and distributed fiber-optic sensing. The sweep nonlinearity and phase noise of laser are the key issues to be dealt with for the broadband optical linear frequency sweep in OFDR systems. In this work, we report on laser sweep nonlinearity and phase noise control based on delay self-heterodyne optical phase locking, which allows highly linear laser frequency sweep with an 8 GHz sweep range and a 160 GHz/s sweep rate with low phase noise. Experiments on both fiber-optic link monitoring and distributed fiber strain sensing are carried out based on such laser source. In the former experiment, we achieve long-distance OFDR with a dynamic range of 27 dB and a high spatial resolution of 4.3 cm over a 240 km fiber-optic link. In the latter, distributed strain sensing with 5 cm spatial resolution is realized. The experiments verify the effectiveness and superiority of the proposed method in controlling laser frequency sweep errors by phase locking.