Lateral divergence angle reduction of semiconductor lasers with loss-enhanced supersymmetric structure

This work proposes and fabricates a loss-enhanced supersymmetric semiconductor laser. By introducing a loss-enhanced slot (LE-slot) into the supersymmetric waveguide arrays, additional loss is imposed on photons propagating within these arrays, thereby increasing the lasing threshold of the corresponding modes. Consequently, a small horizontal far-field (HFF) divergence angle is maintained even at high injection currents. The laser achieved a quasi-single-lobed horizontal far-field distribution at an injection current of 0.5 A with an output power of 200 mW. At a current of 1.5 A, it delivered an output power of 692 mW while maintaining a HFF divergence angle full width at half maximum (FWHM) of 1.5°. This value exhibits a significant advantage compared to the HFF divergence angle FWHM of a supersymmetric laser without a LE-Slot, which is 5.97° at the same current and 2.97° at a comparable output power level.