体布拉格光栅反射率对外腔半导体激光阵列输出光谱的影响

采用记录在光致热敏折射率玻璃中的反射型体布拉格光栅作为反馈元件构成外腔半导体激光阵列,对其输出光谱特性进行了实验研究,分析了快轴准直透镜的位置对外腔反馈耦合效率的影响。实验结果表明,在体布拉格光栅外腔反馈作用下,半导体激光阵列输出光谱中心波长得到锁定,同时输出线宽显著变窄。重点研究了体布拉格光栅的反射率对外腔反馈半导体激光阵列输出光谱特性以及激光器效率的影响。实验结果表明,体布拉格光栅反射率的增加可提高半导体激光阵列内腔模式的抑制效果,提高输出光谱对比度,减小输出光谱线宽。使用反射率为30%的体布拉格光栅,可将半导体激光阵列的输出波长锁定在808nm附近,输出光谱线宽压缩至0.18nm。外腔半导体激光器的输出功率达24.8W,效率为82.6%。

Influence of Volume Bragg Grating Reflectivity on Spectrum of External Cavity Laser Diode Array

The external cavity laser diode array (LDA) with volume Bragg grating (VBG) recorded in photo-thermo-refractive (PTR) glass as wavelength selected element is studied experimentally. The influence of fast-axis-collimation on coupling efficiency is studied. Experimental results indicate that the wavelength of the LDA is locked and the line-width is narrowed sharply under the effect of VBG external cavity. The influence of VBG reflectivity on spectral characteristics and efficiency of external cavity LDA is studied mainly. Experimental results show that the increase of VBG reflectivity can inhibit the intra-cavity mode effective and enhance the contrast of spectrum and narrow the line-width. Using the VBG with a reflectivity of 30%, an output power of 24.8 W is obtained with the linewidth down to 0.18 nm, which corresponds to the efficiency of 82.6% compared with the output power in free-running LDA.