Laterally coupled distributed feedback type-I quantum well cascade diode lasers emitting near 3.22 mu m

摘要

The laterally coupled distributed feedback (LC-DFB) GaSb-based type-I quantum well cascade diode lasers using the second- and the sixth-order gratings to stabilize the output spectrum near 3.22 mu m were designed and fabricated. The laser heterostructure contained three cascades. The devices were manufactured using a single dry etching step defining the similar to 5-mu m-wide ridge with similar to 5-mu m-wide gratings sections adjacent to the ridge sides. The grating coupling coefficients were estimated to be about 1 cm(-1). The stability of the single-frequency operation was ensured by alignment of the DFB mode to the relatively wide gain peak. The 2-mm-long second-order LC-DFB lasers generated above 10 mW of continuous-wave (CW) output power at 20 degrees C in epi-side-up configuration and demonstrated power conversion efficiency above 2%. The sixth-order LC-DFB lasers showed lower efficiency but still generated several milliwatts of CW output power. The devices demonstrated a CW current tuning range of about 3.5 nm at the temperature of 20 degrees C. (C) 2017 Optical Society of America