Single-mode InAs/GaAs quantum-dot DFB laser with oxidized aperture confined surface grating

InAs/GaAs quantum dot (QD) distributed feedback (DFB) lasers are promising candidates for the next-generation photonic integrated circuits. We present a design that incorporates an oxidized aperture confined surface grating (OASG) structure, which reduces non-radiative recombination losses and surface optical losses sustained in a device fabricated by conventionally fabrication methods including etching and regrowth. The OASG-DFB laser eliminates the need for ridge waveguide etching and avoids instability in sidewall grating coupling. Experimental results show stable single-mode operation, a maximum output power of 15.1 mW, a side-mode suppression ratio of 44 dB, and a narrow linewidth of 1.79 MHz. This approach simplifies fabrication, reduces costs, and enhances the scalability of GaAs-based QD DFB lasers for applications in optical communication and photonic integration.