High Performance Surface Grating Distributed Feedback Quantum Cascade Laser

We report on the development of λ ~ 4.7 μm continuous-wave (CW) operation of surface grating distributed feedback (DFB) quantum cascade lasers (QCLs). A high wall plug efficiency (WPE) of 7% is obtained at 15°C from a single facet producing over 0.85 W of CW output power. The threshold current density of DFB QCL is as low as 1.19 kA/cm at 15°C and 2.29 kA/cm at 90°C in CW mode. Single-mode operation with side mode suppression ratio above 25 dB is observed in the working temperature of 15°-95°C.