We demonstrate a high-speed 8.5 μm quantum cascade laser with room temperature continuous wave operation. The maximum output power of 141 mW is obtained at 20 ℃. The parasitic capacitance of the device is decreased from 36.6 pF to 7.1 pF by monolithic integrating a π-shape metal contact electrode. This results in an increase in the -3 dB RF modulation bandwidth from 870 MHz to 4.5 GHz compared with the conventional electrode configuration.
Interband cascade laser arrays with continuous-wave (CW) watt-level output power at room temperature are demonstrated. A three-emitter laser array episide-down bonded on a diamond submount exhibited a CW output power in excess of 1 W at 10℃. The wall-plug efficiency of the laser array is almost the same as that of a single emitter, indicating that there is little heat accumulation caused by the thermal interference between the emitters in the array structure.