Wang Yiping, Zhang Jiejun, Coutinho Olympio, Yao Jianping
Opt Lett. 2015 Nov 1;40(21):4923-6. doi: 10.1364/OL.40.004923.
An approach to the interrogation of a linearly chirped fiber Bragg grating (LCFBG) sensor using a linearly frequency-modulated (or chirped) optical waveform (LFMOW) with a high resolution is proposed and experimentally demonstrated. An LFMOW is generated at a laser diode through linear frequency modulation. The generated LFMOW is then launched into an LCFBG pair consisting of two identical LCFBGs, with one serving as a sensing LCFBG and the other as a reference LCFBG. The reflection of the LFMOW from the two LCFBGs would lead to two time delayed LFMOWs. By beating the LFMOWs at a photodetector, a microwave signal with a beat frequency that is proportional to the time delay difference between the two reflected LFMOWs is generated. By measuring the frequency change of the beat signal, the strain applied to the sensing LCFBG is estimated. The proposed approach is experimentally evaluated. An LCFBG sensor with a resolution of 0.25 με is experimentally demonstrated.
提出并通过实验证明了一种使用具有高分辨率的线性调频光学波形（LFMOW）来询问线性啁啾光纤布拉格光栅（LCFBG）传感器的方法。通过线性频率调制在激光二极管处产生LFMOW。然后将产生的LFMOW发射到由两个相同的LCFBG组成的LCFBG对中，其中一个用作传感LCFBG，另一个用作参考LCFBG。LFMOW从两个LCFBG的反射将导致两个时延的LFMOW。通过在光电探测器处对LFMOW进行拍频，产生一个拍频与两个反射LFMOW之间的时延差成比例的微波信号。通过测量拍频信号的频率变化，估计施加到传感LCFBG上的应变。对所提出的方法进行了实验评估。实验证明了一种分辨率为0.25 με的LCFBG传感器。
