We first study the effect of cavity modes propagating in the lateral dimension on high-power semiconductor lasers with a large stripe width. A sidewall microstructure was fabricated to prevent optical feedback of lateral resonant modes. Theoretically, we demonstrate the existence of lateral resonant modes in the Fabry–Perot cavity with a large stripe width. Experimentally, we design the corresponding devices and compare them with conventional broad-area diode lasers. About a 15% reduction in threshold current and a 27% increase in maximum electro-optical conversion efficiency are achieved. The amplified spontaneous emission spectrum is narrowed, which proves that lateral microstructures suppress optical feedback of lateral resonant modes. Under a large continuous-wave operation, the maximum output power of laser device is 43.03 W, about 1 W higher than that of the standard broad-area laser at 48 A.

We studied the spectral beam combining (SBC) of a large optical cavity (LOC) laser array to achieve high-power and high-brightness laser output. We discussed the characteristics of the external cavity feedback efficiency and the focal length of the transform lens for lasers with different waveguide thicknesses. We have found that using LOC laser diodes can increase the proportion of external cavity feedback, thereby improving the SBC efficiency. At a current of 90 A, the CW output power of the SBC system is 59.2 W, and the SBC efficiency reaches up to 102.8%. All emitters of the laser array have achieved spectral locking with a spectral width of 11.67 nm, and the beam parameter product is 4.38 mm·mrad.