采用二氧化碳激光逐点刻写技术对2 μm波段长周期光纤光栅(LPFG)的传输特性进行了实验研究,探索了光栅周期、折射率调制深度、光栅周期数等光栅刻写参数对光纤光栅在2 μm波段特征损耗峰的影响。仿真和实验结果均表明,2 μm波段LPFG的谐振中心波长和谐振峰深度可分别通过光栅周期以及光栅长度来调谐,激光扫描次数以及折射率调制都将增加光纤内模式的耦合强度。此外还探究了2 μm波段LPFG对于环境温度的敏感特性,通过设计实验测得该波段LPFG的温度灵敏性为74 pm/℃。该研究在2 μm波段光纤激光器及其应用的核心器件方面有潜在的应用价值。

The CO2 laser point-by-point exposure technique is used to fabricate a long period fiber grating (LPFG) operating at 2 μm, and the transmission characteristics are also been experimentally explored. The influences of grating writing parameters including grating period, modulation depth of refractive index and number of grating period on characteristic loss peak at 2 μm waveband are studied. The simulated and experimental results show that the resonance center wavelength and resonance peak depth of LPFG at 2 μm are tuned by grating period and grating length, and laser scanning times and refractive index modulation will increase the coupling strength of the mode within the fiber. In addition, the temperature-sensitive property of a 2 μm LPFG is also explored and the sensitivity is measured to be 74 pm/℃ via the designed experiment. It is believed that this work possesses potential application value in the development of 2 μm fiber lasers and their key devices.