On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers.

W J Liu,J Y Zhang,X L Hu,Z P Cai,H Akiyama,L Y Ying,S Q Chen,B P Zhang

doi:10.1038/srep09600

Abstract

Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400 nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355 nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355 nm pulsed laser. These were explained by taking into account of the significant heating effect under 355 nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs.

Highlights

Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated
Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs
Different cavity lengths of the VCSELs were obtained through varying the thickness of the n-GaN layer

Summary

Introduction

Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs. O ver the past few years, GaN-based vertical-cavity surface-emitting lasers (VCSELs) have been attracting much attention owing to their superior properties over edge-emitting lasers and potential applications in high-density optical storage, large area laser displays, lighting devices, etc. One is the hybrid distributed Bragg reflector (DBR) VCSEL structure combining an epitaxially grown DBR and a dielectric DBR1–4 In this case, the most challenging problem is the preparation of high reflectivity nitride-based DBR with smooth epitaxial surface due to the large lattice mismatch between GaN and AlN (AlGaN).

Methods

Results

Conclusion