Transverse mode control by etch-depth tuning in 1120-nm GaInAs/GaAs photonic crystal

Robust and tolerant single-transverse-mode photonic crystal GaInAs vertical-cavity surface-emitting lasers are fabricated and investigated. Triangular lattice patterns of rectangular air holes of various etch-depths are introduced in the top mirror. The stable single-transverse-mode operation is observed with a large margin of allowance in the etch depth (t=2.5+/-0.6 mum). This stable mode selection mechanism is explained by the mode competition between the two lowest photonic crystal guided modes that are influenced by both the index guiding effect and the etch-depth dependent modal losses. (C) 2004 Optical Society of America.