Opt Lett. 2022 Nov 1;47(21):5533-5536. doi: 10.1364/OL.474295.
In this Letter, we report a novel, to the best of our knowledge, and simple approach for passive quadrature-phase demodulation of relatively long multiplexed interferometers based on two-channel coherence correlation reflectometry. Two-wavelength channels are generated using a single unmodulated CW-DFB diode laser and an acousto-optic frequency shifter. The introduced frequency shift determines the optical lengths of the interferometers. In our experiments, all interferometers have the same optical length of 32 cm corresponding to the π/2 phase difference between channel signals. An additional fiber delay line was introduced between channels to destroy coherence between initial and frequency-shifted channels. Demultiplexing of channels and sensors was performed using correlation-based signal processing. Amplitudes of cross correlation peaks obtained for both channels were used to extract the interferometric phase for each interferometer. Phase demodulation of relatively long multiplexed interferometers is experimentally demonstrated. Experimental results prove that the proposed technique is suitable for interrogating a serial array of relatively long interferometers dynamically modulated with phase excursions exceeding 2π. Simultaneous interrogation and phase demodulation were experimentally demonstrated using an in-line array of low-finesse Fabry-Perot interferometric sensors.
在这封信中，我们报告了一种新颖的、据我们所知的、简单的方法，用于基于双通道相干相关反射计的相对长的多路复用干涉仪的被动正交相解调。两个波长通道是使用单个未调制的 CW-DFB 二极管激光器和声光频移器产生的。引入的频移决定了干涉仪的光程。在我们的实验中，所有干涉仪的光程都相同，为 32cm，对应于通道信号之间的π/2 相位差。在通道之间引入了一个额外的光纤延迟线，以破坏初始和频移通道之间的相干性。使用基于相关的信号处理来实现通道和传感器的解复用。使用两个通道获得的互相关峰的幅度来提取每个干涉仪的干涉相位。实验证明了相对长的多路复用干涉仪的相位解调。实验结果证明，该技术适用于对具有超过 2π 的相位偏移的动态调制的相对长的串联干涉仪进行询问。使用在线低精细度 Fabry-Perot 干涉传感器阵列实验证明了同时询问和相位解调。
