Design of low-loss hybrid vertical cavity with a monolithic diffuser

Abstract

The vertical cavity is a basic optical structure used in photonics and lasers. In this work vertical cavities with light diffusing function, composed of high-contrast gratings (HCGs) and distributed Bragg reflectors (DBRs) for 980 nm wavelength range are studies. Cavity modes of DBR–DBR vertical cavity and HCG–DBR vertical cavity are calculated and compared. The hybrid vertical cavity composed of a HCG and a DBR illustrates a hybrid cavity mode with a higher quality factor compared with a DBR–DBR vertical cavity. A heterostructure HCG is designed to reduce the leakage loss of the cavity mode of the HCG–DBR vertical cavity with a higher quality factor, and at the same time serve as a monolithic diffuser to expand the output beam from the heterostructure HCG-VCSEL into a broader angle range. This work is useful for the designs of vertical cavities for novel vertical-cavity surface-emitting lasers with diverse functions.