High single-fundamental-mode power VCSEL integrated with alternating aluminum content micro-lens

The patterned top-emitting vertical-cavity surface-emitting laser (VCSEL) with a fixed diameter etching window was etched in hydrobromic acid solution with anisotropic etching. An all-semiconductor micro-lens that consisted of alternating aluminum content was directly formed on the output window. The etched curved surface with designed curvature radius makes the mirror loss located at the convex region differ from the edge region. Higher-order modes experience larger mirror loss and are therefore filtered out. The VCSEL with the designed micro-lens reaches a 3.14 mW single-mode power with side-mode suppression ratio >25 dB, which is over 50 times higher than the 0.06 mW single-mode power of the reference VCSEL.