Monolithic high contrast grating VCSELs: Concept and prospects

Abstract

Recent trend in the research focused on optical communication is to increase the speed and energy efficiency of the signal sources. In the same time, it is highly desirable to decrease the size of the source into submicron level. The driving forces for achieving these goals are growing market for optical interconnects which are widely used in large datacenters and the silicon photonics which in a short time will create a huge market for optical and electronic circuits integrated in a single chip. We present results of simulations of a novel, ultra-small VCSEL device of extremely simplified design. The device uses monolithic high contrast grating (MHCG) mirrors instead of the commonly used distributed Bragg reflectors (DBR). We show that very high reflectivity, required to sustain a VCSEL lasing, can be achieved by a shallow etching of the surface of the laser cavity only. Thanks to the extraordinary features of the MHCG mirror, the cavity and the mirror can be made of a single material. We show that the concept allows fabrication of VCSELs in all material systems used in optoelectronics, e.g. GaN, InP, GaSb, ZnO, Si, etc. Although several times smaller vertical dimensions of MHCG VCSELs in comparison to conventional VCSELs, their properties are comparable with standard DBR VCSELs.