Single-mode surface grating semiconductor laser fabricated by i-line projection photolithography

The study presents the design, fabrication, and testing of the 4th-order surface grating laser with a focus on achieving stable single-mode emission. This approach contrasts with traditional high-order surface gratings, aiming to minimize loss and enhance the yield of single-mode operations. The laser device showcases a remarkable single-mode performance, with an injection current of I_FP = 57 mA and I_Grating = 20 mA, achieving a side mode suppression ratio of 56.97 dB. The threshold current remains around 11 mA, reaching a peak power output of 5 mW. The experimental results highlight the potential of using low-order surface gratings for efficient single-mode lasers, streamlining the fabrication process while enhancing device performance.