Optically pumped GaN vertical cavity surface emitting laser with high index-contrast nanoporous distributed Bragg reflector.

Seung-Min Lee,Su-Hyun Gong,Mohamed Ebaid,Jin-Ho Kang,Yong-Hoon Cho,Sang-Wan Ryu

doi:10.1364/oe.23.011023

Abstract

Laser operation of a GaN vertical cavity surface emitting laser (VCSEL) is demonstrated under optical pumping with a nanoporous distributed Bragg reflector (DBR). High reflectivity, approaching 100%, is obtained due to the high index-contrast of the nanoporous DBR. The VCSEL system exhibits low threshold power density due to the formation of high Q-factor cavity, which shows the potential of nanoporous medium for optical devices.

Highlights

Semiconductor optical devices have been developed with advances in compound semiconductor technology since 1960s, e.g., III-V and II-VI compounds, along with various types of optical devices, such as light-emitting diode [1], laser diode [2], and photodiode [3]
The vertical cavity surface emitting laser (VCSEL) system exhibits low threshold power density due to the formation of high Q-factor cavity, which shows the potential of nanoporous medium for optical devices
These results, taken together with the high Q-factor, indicated that nanoporous GaN is advantageous to fabricate high-performance distributed Bragg reflector (DBR) due to the controllability of refractive index

Summary

Introduction

Semiconductor optical devices have been developed with advances in compound semiconductor technology since 1960s, e.g., III-V and II-VI compounds, along with various types of optical devices, such as light-emitting diode [1], laser diode [2], and photodiode [3]. The poor performance of current GaN DBRs requires a new approach that can provide a large index-contrast, high electrical and thermal conductivities, and ease of manufacture. The controllability of refractive index via nano-porosification will offer tremendous potential for designing optical devices under the limit of available materials. The improvement of maximum reflectivity was achieved based on more advanced EC etching for uniform and sturdy nanoporous GaN with newly developed electrolyte. This nanoporous DBR was adopted to realize a VCSEL cavity and continuous wave (CW) lasing action of the VCSEL through optical pumping was demonstrated at room temperature

Fabrication of nanoporous DBR and VCSEL

Optical characterization of nanoporous VCSEL

Results and discussion

Conclusion