Ning Chao, Sun Rui-Xuan, Liu Shu-Man, Zhang Jin-Chuan, Zhuo Ning, Liu Jun-Qi, Wang Li-Jun, Zhai Shen-Qiang, Liu Feng-Qi, Wang Zahn-Guo
Opt Express. 2022 Aug 1;30(16):29007-29014. doi: 10.1364/OE.465716.
A second-order distributed feedback interband cascade laser emitting at 3.25 µm was designed, grown, and fabricated. By coherent epitaxy of a GaSb cap layer instead of the conventional thin InAs cap on top of the laser structure, a high-quality surface grating was made of GaSb and gold. Enough coupling strength and a significant inter-modal loss difference were predicted according to the simulation within the framework of couple-wave theory. Lasers having 2-mm-long cavities and 4.5-µm-wide ridges with high-/anti-reflection coatings were fabricated. The continuous-wave threshold current and maximum single-mode output power were 60 mA and 24 mW at 20°C, respectively. The output power of 5 mW was still kept at 55°C. Continuous tuning free from mode hopping and high single-mode suppression ratios (>20 dB) were realized at all injection currents and heat-sink temperatures, covering a spectral range of over 20 cm.
设计、生长并制造了一种发射波长为3.25μm的二阶分布反馈带间级联激光器。通过在激光结构顶部采用GaSb帽层的相干外延生长，而非传统的薄InAs帽层，利用GaSb和金制作了高质量的表面光栅。根据耦合波理论框架内的模拟预测，获得了足够的耦合强度和显著的模式间损耗差异。制造出了具有2mm长腔和4.5μm宽脊且带有高/抗反射涂层的激光器。在20°C时，连续波阈值电流和最大单模输出功率分别为60mA和24mW。在55°C时仍保持5mW的输出功率。在所有注入电流和热沉温度下，实现了无模式跳变的连续调谐以及高单模抑制比（>20dB），覆盖光谱范围超过20cm。
