Surface-emitting distributed feedback quantum-cascade lasers operating at \lambda \approx 7.8 \mu m are demonstrated. The metal-covered second-order grating is shallow-etched into the surface of a thin InGaAs contact and cladding layer. This forms a hybrid waveguide and used to achieve relatively low waveguide losses and high coupling strengths. The devices exhibit stable single-mode operation from 90 to 130 K with a side mode suppression ratio above 20 dB. A slope efficiency of 194 mW/A is obtained at 90 K, which is twice higher than that of the Fabry-Perot counterpart.
© 2011 Chinese Optics Letters
(230.1950) Optical devices : Diffraction gratings
(250.7270) Optoelectronics : Vertical emitting lasers
(250.7360) Optoelectronics : Waveguide modulators
(140.5965) Lasers and laser optics : Semiconductor lasers, quantum cascade
Wanhong Guo, Junqi Liu, Jianyan Chen, Lu Li, Lijun Wang, Fengqi Liu, and Zhanguo Wang, "Single-mode surface-emitting distributed feedback quantum-cascade lasers based on hybrid waveguide structure," Chin. Opt. Lett. 9, 061404- (2011)