The Phase Noise Transfer Model in the Phase-Generated-Carrier-Based Interferometric Fiber-Optic Sensor

The phase-generated-carrier (PGC) method is one of the popular interrogation methods for the interferometric fiber-optic sensor systems. Among varieties of specifications, the noise characteristic is a key one that determines the minimum detectable signal. However, the mechanism of the noise transfer process in the PGC-based interferometric fiber-optic sensor has not been reported to the best knowledge. In this paper, the influences of three different types of noise sources on the noise floor of the PGC-based interferometric fiber-optic sensor system are studied systematically. On the basis of that, the phase noise transfer model is built and verified experimentally. The results depict that the theoretical model can well predict the experimental result. With the proposed theoretical model, the prediction and analysis of the output phase noise in the PGC-based interferometric fiber-optic sensor is available. In addition, the proposed model provides a potential support for locking the initial phases to suppress the common-mode noise in the PGC-based system. In this sense, the proposed model is a significant tool for the noise-target design and construction of the PGC-based in terferometric fiber-optic sensor system.

I. Introduction

The phase-generated-carrier (PGC) method is one of the widely used interrogation methods in the interferometric fiber-optic sensor (IFOS) [1]–[13]. Compared with the IFOS based on the differential delay heterodyne (DDH) method, the one utilizing the PGC method can achieve a simple architecture and low pick-up noise on the transmission link. Therefore, the PGC method is more suitable for the specific application in which the transmission link keeps swinging, like the towed array [1]. Due to the mentioned advantages, the PGC method and its amelioration remain a hot topic.