Optical Microfiber All-Optical Phase Modulator for Fiber Optic Hydrophone.

Minwei Li,Shangpeng Qin,Yang Lu,Junbo Yang,Junyang Lu,Xiaoyang Hu,Yaorong Wang,Yang Yu,Zhenrong Zhang

doi:10.3390/nano11092215

Abstract

In order to meet the needs of phase generated carrier (PGC) demodulation technology for interferometric fiber optic hydrophones, we proposed an optical microfiber all-optical phase modulator (OMAOPM) based on the photo-induced thermal phase shift effect, which can be used as a phase carrier generation component, so as to make the modulation efficiency and working bandwidth of this type of modulator satisfy the requirements of underwater acoustic signal demodulation applications. We analyzed the modulation principle of this modulator and optimized the structural parameters of the optical microfiber (OM) when the waist length and waist diameter of OM are 15 mm and 1.4 μm, respectively. The modulation amplitude of the modulator can reach 1 rad, which can meet the requirements of sensing applications. On this basis, the fiber optical hydrophone PGC-Atan demodulation system was constructed, and the simulated underwater acoustic signal test demodulation research was carried out. Experimental results showed that the system can demodulate underwater acoustic signals below 1 kHz.

Highlights

With the development of optical fiber sensing technology, various types of optical fiber sensors have the advantages of simple manufacturing, low cost, and small size
To further optimize the performance of the modulator, we studied the influence of the waist an all-optical phase modulator based on the photo-induced thermal phase shift effect can be developed [28]
A novel phase generated carrier device based on the photo-induced thermal phase shift effect is proposed in this paper

Summary

Introduction

With the development of optical fiber sensing technology, various types of optical fiber sensors have the advantages of simple manufacturing, low cost, and small size. They show good application potential in the field of ocean exploration [1,2]. According to different sensing principles, fiber optic hydrophones can be divided into interference type and fiber-grating type [6]. Interferometric hydrophones can be divided into different structures of interferometers: the Mach-Zehnder interferometer, Michelson interferometer, Fabry–Perot interferometer, and Sagnac interferometer. The Michelson interferometer hydrophone is widely used in various underwater acoustic environment monitoring systems because of its simple structure, high sensitivity, and easy array formation

Results

Discussion

Conclusion