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采用相位掩模板法,实验研究了准分子激光器制作光纤布拉格光栅(FBG)过程中,紫外光热效应对光栅生长过程和光谱结构的影响。研究发现,相位掩模板法直接曝光法中,对同一段光敏光纤进行累加曝光,其反射率不会随着曝光量的增大而线性增长,而在多次曝光时会产生光栅反射率变小的“漂白”现象,并且多次曝光的时间间隔越短,“漂白”的过程也越长;相同的曝光量下,激光器重复频率越高,则曝光所用时间越短,所形成的光纤光栅的反射率越高;扫描曝光制作光纤光栅时,在相同的曝光参数下,扫描移动方向的不同会导致光栅旁瓣分布规律的不同,由此提出了光栅制作过程中存在“热致啁啾”现象。
The influence of UV thermal effect on the grating growth process and the spectral structure was experimentally studied by using the phase reticle method during the fabrication of fiber Bragg grating (FBG) by an excimer laser. The study found that the phase mask method of direct exposure method, the same period of photosensitive optical fiber cumulative exposure, the reflectivity will not increase linearly with the increase of exposure, and in the multiple exposure will have a smaller grating reflectivity Of the “bleach” phenomenon, and the shorter the multiple exposure time interval, “bleach” the longer the process; the same exposure, the higher the laser repetition frequency, the exposure time is shorter, the formation of , The higher the reflectivity of the FBG is. When the scanning exposure is used to fabricate the FBG, different directions of the scanning shift will result in different side-lobes distribution under the same exposure parameters. Therefore, it is proposed that the grating has a “ To chirp ”phenomenon.