中国微米纳米-高精度光纤光栅地震计

光纤地震观测仪器具有传感器无源、抗电磁干扰性强、深井观测耐高温高压、抗雷击等优点,可为地震观测提供一种新的技术手段.光纤地震计的敏感元件采用相移光栅代替传统的光纤光栅,相比于传统的光纤光栅,其光谱线宽要窄4个数量级,可以获得了更高的反射光谱信噪比和更高的波长解调精度.对于相移光栅式光纤地震计,其反射光谱波长与所测的地震波具有良好的线性关系,只需要解调出相移光栅的波长漂移信号就可以推算得到地震波信息.采用该技术,可以实现精度在ng级、测量频带DC~50 Hz的震动信号测量.2015年4月-6月,在云南省昭通防震减灾局的协助和配合下,于昭通市巧家地震观测站进行了光纤地震计试验.可清晰记录临近发生的地震信号.

High Resolution Fiber Optic Seismometer

Fiber optic sensor based earthquake monitoring instruments have some advantages such as passive monitoring,immunity to EMI,reliability in high temperature and pressure environment,immunity to lightening,which can provide a new approach to earthquake observation.We propose a high resolution fiber optic seismometer based on phase-shift fiber Bragg grating(π-FBG).Compared with conventional FBG,the π-FBG has a narrower linewidth by four orders of magnitude,which result in lower noise level and higher resolution.The reflective wavelength of the π-FBG is linear to the magnitude of earthquake wave and we can demodulate the earthquake information by demodulating the wavelength shift of π-FBG.A resolution of ng within bandwidth of DC-50 Hz is achieved.In April 2015,the fiber optic seismometer is installed in Zhaotong city,Yunnan Province.The earthquake events were well recorded.