High power mid-infrared GaSb-based lasers are desired for many applications, however, the self-heating in the active region is still one of the main influence factors for practical application. In this paper, we report on fabrication and characterization of high-power GaSb-based lasers. The temperature dependence of output performance of the device was investigated. Due to the high quality of epitaxy and wide waveguide design, the lasers exhibited a high-power capability from 288 K to 318 K. Devices with a cavity length of 1.5 mm and an aperture of 100 μm delivered a power of 1.46 W at a current of 7 A at 288 K and remains 1.10 W at 318 K under CW operation limited by thermal rollover. The characteristic temperature T0 is 151 K and 68 K below and above 298 K, respectively.

Symmetric narrow waveguide structure has been developed and fabricated to achieve low beam divergence and improved coupling performance of the 1.95 μm GaSb-based single-transverse-mode diode lasers. The near-field expansion effect of the narrowed 150 nm vertical waveguide design leads to a reduced fast-axis beam divergence of 44.2° full width at half maximum (FWHM) as well as 62% single-mode fiber (SMF) coupling efficiency, which has 55% relative promotion compared to the 40% efficiency of the conventional 270 nm waveguide design with 60.4° FWHM. The highest SMF coupling power of 113 mW was obtained by the 210 nm narrow waveguide lasers with lower internal optical loss at a 55% coupling efficiency, which performed balanced optimal performance with a narrowed divergence of 53.4° and a relatively high optical power of 206 mW. The high coupling efficiency and power will provide more promising prospects for the GaSb-based single-transverse-mode lasers in the widespread fiber-based and external-cavity applications.