线性啁啾光纤光栅局部点加热光谱特性的研究

对线性啁啾光纤光栅（LCFBG）进行局部点加热时，在不同加热温度、加热宽度和加热位置情况下的输出光谱特性进行了研究。通过数值模拟发现，改变栅区局部加热点的温度和宽度，对透射禁带中窄带透射峰的透射率有较为明显的影响，其透射峰的中心波长也将会发生一定的漂移；透射峰的中心波长与栅区局部加热点的位置存在线性对应关系，且透射峰波长变化范围可覆盖整个透射禁带；LCFBG啁啾系数的大小，决定了改变加热位置导致的透射峰波长的调谐速率。基于理论研究结果，以热敏打印头的加热阵列为加热源，对LCFBG栅区进行局部点加热时的输出光谱特性进行了实验研究，得到了重复性和稳定性都较好、可多波长调谐的窄带透射峰。在实验误差范围内，实验结果与数值模拟得到的结论较为一致。

Investigation of the spectral characteristics of a linearly chirped fiber Bragg grating with local point heating

The output spectrum characteristics of a linearly chirped fiber Bragg grating (LCFBG) under localized point heating with different heating temperatures, widths and positions were investigated. The numerical simulation shows that the heating temperature and heating width applied onto the LCFBG have an obvious influence on the transmissivity and central wavelength of narrow-band transmission peaks in the transmission bandgap. The central wavelengths of the transmission peaks have a good linear relationship with the local heating positions of the LCFBG and can shift in the whole transmission bandgap region. The chirp coefficient of the LCFBG determines the wavelength tuning velocity of the transmission peaks induced by the change in the heating position. Based on the theoretical results, the spectral characteristics of the LCFBG are investigated experimentally using a commercial thermal printhead as a local heating source. The narrow-band transmission peaks are realized with high performance in terms of reproducibility, stability and potential multiwavelength tunability. The experimental results are in good agreement with those of the numerical simulation within the experimental error.