Direct observation of higher-order whispering-gallery modes in VCSELs at room temperature by embedding a defect-free surface micro-structure

TL;DR

This paper presents a novel method to directly observe higher-order whispering-gallery modes in VCSELs at room temperature by micro-structuring the surface to suppress lower-order modes, enabling detailed mode analysis.

Contribution

The study introduces a defect-free surface micro-structure technique to observe high-order whispering-gallery modes in VCSELs without adding defects.

Findings

Observation of up to the 23rd azimuthal order mode

Suppression of lower-order modes via surface micro-structure

Correlation between experimental patterns and numerical simulations

Abstract

We propose and demonstrate a direct method to observe higher-order whispering-gallery modes in vertical cavity surface emitting lasers (VCSELs) at room temperature. Instead of introducing any defect mode, we show that suppression of lower-order cavity modes can be achieved by destroying vertical reflectors with a surface micro-structure. Up to the 23rd azimuthal order whispering-gallery mode confined laterally by the native oxide layers is observed in experiments through collecting near-field radiation patterns. Various vertical emission transverse modes are identified by the spectrum in experiments as well as numerical simulations.