Semiconductor lasers emitting in the mid-infrared wavelength region are of particular importance since the strong absorption bands of several technologically and industrially relevant gas species are located in this range, such as CO, CH4, NH3 and HF. These lasers are generally required a low throshold current with good single mode operation for simple and accurate gas detection. GaSb-based semiconductor material is an ideal system for realizing this mid-infrared laser due to its narrow bandgap. In this paper, we present a new design of high performance single mode GaSb DBR laser based on high order slotted surface grating for gas detection. The 2D scattering matrix method combing with the time-domain travelling-wave model has been used for the optimization of slotted surface grating to enlarge the reflection and reduce the loss. The designed 2.3μm single mode GaSb surface-grating DBR laser has been predicted with a low threshold-current of about 8 mA and a slope efficiency of about 0.14 mW/mA. The laser scheme is of a single wafer growth, can be easily fabricated, and thus has great potential to realize cost effective with high reliability.
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