Watt-level, high wall plug efficiency, continuous-wave room temperature quantum cascade laser emitting at 7.7μm

In this article, a InP based strain-balanced In0.58Ga0.42As/In0.47Al0.53As quantum cascade laser emitting at 7.7 mu m is reported. The active region is based on a slightly-diagonal bound to continuum design with 50 cascade stages and a low voltage defect Delta(inj) of 96 meV. By optimizing the active region and waveguide structure, the waveguide loss alpha(w) of 1.18cm(-1) are obtained, which contribute to a high wall-plug efficiency (WPE) of 9.08% and low threshold current of only 1.09 kA/cm(2) in continuous-wave(CW) operation at 293K. The maximum single facet output power of 1.17W in CW operation and 2.3W in pulsed operation are measured at 293K. The narrow ridge and buried ridge structure epi-side-down-mounted on the diamond heatsink improved the heat dissipation of the device. A beam of pure zero order mode and a broad external-cavity tuning range from 7.16 mu m to 8.16 mu m are also achieved. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement