Single-mode narrow-linewidth semiconductor laser based on oxidized aperture and shallowly etched slots

• A single-mode narrow-linewidth semiconductor laser based on an oxidized aperture and shallowly etched surface slots. • Oxidized aperture waveguide provides both optical and current confinement, ensuring stable single lateral mode operation. • Shallowly etched surface slots offer in-plane feedback to achieve single-longitudinal-mode operation. • Fabrication is simplified via standard i-line photolithography, avoiding high-cost EBL and complex regrowth. We demonstrate a novel single-mode narrow-linewidth semiconductor laser based on an oxidized aperture and shallowly etched surface slots. The proposed structure simplifies the fabrication process via standard i-line photolithography, eliminating the need for complex epitaxial regrowth and significantly reducing etching-related challenges. By avoiding conventional fabrication steps such as ridge etching and epitaxial regrowth, our design effectively mitigates non-radiative recombination losses and surface optical losses typically encountered in traditional device fabrication. Experimental results verify stable single-mode operation over a broad range of injection currents (150–400 mA) and operating temperatures (15–40 °C), with a maximum output power of 20 mW, a side-mode suppression ratio up to 42 dB, and a narrow linewidth of 638 kHz. With its high performance, fabrication simplicity, and low cost, this laser offers a promising solution for advanced photonic applications such as optical communications, coherent detection, and microwave photonics.