光热敏折变玻璃的体布拉格光栅热特性理论研究

Investigation on the thermal properties of volume Bragg grating in photo-thermo-refractive glass

光热敏折变(photo-thermo-refractive,PTR)玻璃材质的体布拉格光栅(volume Bragg grating,VBG)在外腔半导体激光器(laser diode,LD)光谱特性改善领域具有较为广泛的应用。基于有限元分析方法,研究了LD辐照高度、LD功率和工作温度对VBG热分布的影响。在LD功率为40 W和工作温度为25℃的工作条件下,辐照高度分别为1.48、0.88和0.28 mm时,VBG的最高温升分别为8.52、5.07、2.20℃。辐照区域内的温度与工作温度的偏差随LD功率升高等比例变大。升高VBG工作温度,可以缩小辐照区域内的实际温度与工作温度的差距。结果表明,通过优化辐照高度和LD的工作参数,可以实现VBG工作区域较小的温度梯度分布。

Volume Bragg gratings （VBG） fabricated by photo-thermo-refractive glass are widely adopted in linewidth-narrowing of laser diode with external cavities. The model was based on finite element analyses. Through the model, thermal properties of the VBG were researched under conditions of different laser diode （LD） illumining area, different laser power and different gratings＇ working temperature. When the LD power was 40 W and the working temperature was 25℃, the increase of the maximal temperature are 8.52, 5.07 and 2.20 ℃ at the illuminated altitude of 1.48, 0.88 and 0.28 ram. The discrepancy between the temperatures of the illuminated area and the working temperature was linear to the LD power. By improving the VBG working temperature, the gap between the actual temperature and the working temperature can be reduced. According to the research, the uniformity of the VBG＇s temperature can be optimized by choosing illuminated area and LD driving conditions, which will be beneficial to acquire the LD with narrow linewidth.