Demonstration of polarization control GaN-based micro-cavity lasers using a rigid high-contrast grating reflector

Tsu-Chi Chang,Kuo-Bin Hong,Shuo-Yi Kuo,Tien-Chang Lu

doi:10.1038/s41598-019-49604-0

Tsu-Chi Chang, Kuo-Bin Hong + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-49604-0

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Journal: Scientific Reports	Publication Date: Sep 10, 2019
Citations: 13	License type: open-access

Affiliation: National Yang Ming Chiao Tung University

Abstract

We reported on GaN microcavity (MC) lasers combined with one rigid TiO2 high-contrast grating (HCG) structure as the output mirror. The HCG structure was directly fabricated on the GaN structure without an airgap. The entire MC structure comprised a bottom dielectric distributed Bragg reflector; a GaN cavity; and a top HCG reflector, which was designed to yield high reflectance for transverse magnetic (TM)- or transverse electric (TE)-polarized light. The MC device revealed an operation threshold of approximately 0.79 MW/cm2 when pulsed optical pumping was conducted using the HCG structure at room temperature. The laser emission was TM polarized with a degree of polarization of 99.2% and had a small divergence angle of 14° (full width at half maximum). This laser operation demonstration for the GaN-based MC structure employing an HCG exhibited the advantages of HCGs in semiconductor lasers at wavelengths from green to ultraviolet.

Highlights

Around the world, GaN-based microcavity (MC) structures used for resonant cavity light-emitting diodes, edge-emitting lasers, vertical cavity surface-emitting lasers (VCSELs), and polaritonic emitters have recently received considerable attention[1,2,3,4,5,6,7]
We demonstrated the lasing action in a GaN MC with an high-contrast grating (HCG) reflector under pulsed optical pumping at room temperature for the first time
For achieving a high reflectance value at a specific wavelength that coincided with the gain peak of GaN, the plane waves with transverse magnetic (TM) and transverse electric (TE) polarizations were normally incident on the GaN facet of the TiO2 grating on the GaN film; scattering parameters (S-parameters) were numerically calculated by employing COSMOL Multiphysics finite-element analysis software

Summary

Introduction

GaN-based microcavity (MC) structures used for resonant cavity light-emitting diodes, edge-emitting lasers, vertical cavity surface-emitting lasers (VCSELs), and polaritonic emitters have recently received considerable attention[1,2,3,4,5,6,7]. For achieving a high reflectance value at a specific wavelength that coincided with the gain peak of GaN, the plane waves with transverse magnetic (TM) and transverse electric (TE) polarizations were normally incident on the GaN facet of the TiO2 grating on the GaN film; scattering parameters (S-parameters) were numerically calculated by employing COSMOL Multiphysics finite-element analysis software.

Results

Conclusion