The resonant wavelength is an important parameter of fiber Bragg grating (FBG). When FBGs are fabricated by femtosecond (fs) laser direct writing, it can be fine-tuned through the process of stress annealing. By changing applied stress, it can be permanently fine-tuned in the range of 20.76 nm relative to the original one, and the tunable sensitivity is 1.48 nm/MPa. Besides, the elastic limit strength of silica can be measured at high temperature by analyzing nonlinear shift of FBG resonance wavelength during the stress annealing process. The temperature sensing properties of FBG are measured from 20 °C to 1150 °C. The sensitivity and high-temperature stability of FBG are improved after stress annealing, which means that the fine-tuned FBG is still suitable for high-temperature sensing, high-power fiber lasers and other high-temperature conditions.

谐振波长是光纤布拉格光栅（FBG）的重要参数。当通过飞秒（fs）激光直接写入制造FBG时，可通过应力退火过程对其进行微调。通过改变施加的应力，可以在相对于原始应力的20.76 nm范围内进行永久性微调，并且可调灵敏度为1.48 nm / MPa。此外，通过分析应力退火过程中FBG共振波长的非线性位移，可以在高温下测量二氧化硅的弹性极限强度。FBG的温度感应特性在20°C至1150°C范围内测量。经过应力退火后，FBG的灵敏度和高温稳定性得到了改善，这意味着微调后的FBG仍然适用于高温感应，高功率光纤激光器和其他高温条件。