Mode switching of high index contrast photonic crystal surface emitting lasers

This paper investigates the phenomenon of mode switching for GaAs-based high index contrast photonic crystal surface emitting lasers (PCSELs) with deeply etched air holes. The room-temperature lasing characteristics and angular resolved photoluminescence spectra of PCSELs show that the lasing mode would change from the fundamental guided mode to a high-order guided mode as the filling factor (FF) increased, resulting from the diffraction of deeply etched semiconductor/air arrays with high index contrast. Higher order guided modes could coherently couple out of photonic crystal and would significantly influence the laser output of PCSELs with a larger air FF, leading to rich far-field characteristics.