A low‐cost single frequency laser, emitting in the mid‐infrared spectral region and dissipating minimal electrical power, is a key ingredient for the next generation of portable gas sensors for high‐volume applications involving chemical sensing of important greenhouse and pollutant gases. Herein, a Quantum Cascade Surface Emitting Laser (QCSEL) is proposed, which is implemented as a short linear cavity with high reflectivity coated end‐mirrors to suppress any edge emission and employs a buried semiconductor diffraction grating to extract the light from the surface. By wafer‐level testing, the cavity length scaling is investigated, mirror reflectivities larger than 0.9 are extracted, and a pulsed threshold power dissipation of 237 mW for an emission wavelength near 7.5 µm is achieved. Finally, single‐mode emission with a side‐mode suppression ratio larger than 33 dB is demonstrated for a 248 µm short cavity, which is mounted with the epitaxial layer up and operated in continuous wave at 20 .

中文翻译：

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量子级联表面发射激光器

低成本单频激光器在中红外光谱区发射且耗散极低的电功率，是下一代便携式气体传感器的关键成分，适用于涉及重要温室气体和污染物气体化学传感的大批量应用。本文提出了一种量子级联表面发射激光器（QCSEL），它被实现为具有高反射率涂层端镜的短线性腔，以抑制任何边缘发射，并采用埋入式半导体衍射光栅从表面提取光。通过晶圆级测试，研究了腔长缩放，提取了大于 0.9 的镜面反射率，并在发射波长接近 7.5 µm 时实现了 237 mW 的脉冲阈值功耗。最后，在 248 µm 短腔中展示了边模抑制比大于 33 dB 的单模发射，该短腔安装有外延层，并在 20 的连续波下工作。