High-brightness green laser diode that uses a multi-order half-wave plate to realize twice-combined polarized beams

•A high-brightness green laser diode that uses a multi-order half wave plate to realize twice-combined polarized beams is provided.•The multi-order half-wave plate changes the polarization state of the first-combined polarized beam with different green wavelengths from orthogonal to parallel.•Compared with the first beam combination, the output power is increased by 22.85% and the brightness by 8.65%•An output power of 2.85 W and a brightness of 25.36 MW/cm2·sr with an optical–optical conversion efficiency of 82.85% and a spectral width of 15.48 nm.