GaSb-based laterally coupled distributed feedback (LC-DFB) quantum well lasers with a wavelength of 2 μm were successfully prepared. Second order Bragg gratings are fabricated by holographic lithography and inductively coupled plasma etching (ICP). The etching conditions for grating preparation are optimized and a single longitudinal mode lasing at room temperature is obtained. The room temperature peak power output per facet exceeds 5 mW with a maximum side-mode suppression ratio of more than 24 dB.