Near 1050 nm laterally coupled DFB laser with tightened-ridge-waveguide for improving grating coupling capability and controlling lateral modes

We report our design and fabrication of a laterally coupled tighten-ridge-waveguide distributed feedback (LC-TRWG-DFB) laser with 37th-order sidewall gratings and 30 µm ridge width. Unlike the LC-DFB lasers with narrow ridge waveguides, our proposed LC-TRWG-DFB improves the output power by widening the width of the ridge waveguide. Simultaneously, the reduction of grating coupling ability and the emergence of high-order lateral modes caused by the widening are mitigated by the tighten structure at the rear of the ridge waveguide. Experimental results demonstrate that by using the tighten-ridge-waveguide, the spectral width is narrowed from 0.72 nm to 0.07 nm, and the temperature-dependent shift in wavelength is reduced from 0.2 nm/K to 0.12 nm/K at 0.4 A. Compared to the LC-DFB laser, the maximum output power of the LC-TRWG-DFB is increased from 136 mW to 328 mW. This study provides valuable insights for the development of high-power LC-DFB semiconductor lasers with a simple fabrication process.