Fiber laser sensing based on mechanically-induced long-period gratings

采用机械压力、光固化胶粘剂和磁力三种方法在纤维中形成压力感应长周期光纤光栅（LPFGs）。虽然LPFG被称为带阻滤波器，但其带通滤波器响应是通过包层-芯模式转换获得的。通过将LPFG引入稀土。在掺铒光纤激光谐振腔中，实现了光纤激光器的可调谐工作。利用激光输出功率和波长随LPFG环境的变化，实现了激光输出特性对温度和压力的同步传感。

Pressure-induced long-period fiber gratings(LPFGs) were formed in fibers by three methods, i. e., mechanical pressure, UV-curable adhesive, and magnetic force. Although the LPFG is known as a band-rejection filter, the bandpass filter response was obtained by cladding-to-core modes conversion. By introducing the LPFG into the rare-earth. doped fiber laser resonator, tunable operation of the fiber lasers was attained. By using the change of the laser output power and the wavelength according to the circumstance of LPFG, simultaneous sensing of temperature and pressure was obtained from the laser output characteristics.