Research On SOA-based Tunable Fiber Ring Laser

Optical fiber sensor can be applied in harsh environments, such as strong electromagnetic interference, high temperature, high pressure, and strong corrosive environment because of its unique advantages compared with conventional electronic sensors. Based on sensor networking technology and optical multiplexing technology, dynamic multi-point measurement system has been developed. Because multi-point dynamic measurement needs ultra-broad bandwidth light source, new requirement has been put up to fiber sensor demodulation system. To solve the above problem, a SOA based tunable fiber ring laser is realized, with high SNR, good flatness and wide tuning range.The performance of tunable fiber ring laser, as the light source of the demodulation system, greatly affects the measurement stability and accuracy and also contributes to multiplexing capability of fiber sensor network. The main research work in the paper is illustrated as followings:(1) Firstly, a brief introduction to various types of optical amplifiers is given. The background and significance of the SOA tunable ring cavity has been analyzed.(2) Spontaneous field, signal radiation field equation and Carrier rate equation are carried out through SOA gain model. In the main time, SOA’s contribution to the short-term stability of the ring laser is studied.(3) A SOA-based fiber ring laser is designed and successfully achieved. Experimental study consists two parts:the scanning range and flatness of output power spectrum. Ultimately, a continuous tuning range of90nm(1520-1610nm) bandwidth is obtained with an output power of2.04mW.3dB laser linewidth is less than35pm, the signal to noise ratio greater than40dB, and the flatness is less than0.7dB.(4) An optical fiber sensor demodulation system based on SOA tunable laser is built up. The system consists of swept laser (SOA based tunable fiber ring laser), wavelength reference(HCN gas absorption cell) part, photoelectric detection part, data acquisition part and data processing part. The accuracy and resolution of wavelength of the calibrated SOA tunable laser are measured. The results are4pm and5.86pm, respectively.