Quantum-Dot Photonic-Crystal Surface-Emitting Lasers with Bottom Distributed Bragg Reflector

Ming-Yang Hsu,Gray Lin

doi:10.3390/photonics5030027

Abstract

Quantum-dot (QD) photonic-crystal (PC) surface-emitting laser (SEL) devices with bottom distributed Bragg reflector (DBR) were fabricated based on vertical-cavity SEL structure with top DBR completely removed. Two-dimensional (2D) PCs were deeply etched through QD multilayers to yield strong diffraction coupling. Room-temperature optically pumped lasing emissions at 1194 nm and 1296 nm were demonstrated for two lattice periods of 360 nm and 395 nm, respectively. Two lasing wavelengths separated over 100 nm; however, there were less than two times difference in threshold power densities while slope efficiencies were comparable. The unique spectral gain characteristics of QDs were considered in interpretation of gain-cavity detuning. Moreover, simulation revealed the sub-cavity should be designed so that its resonant wavelength is in phase with lasing wavelength.

Highlights

Photonic-crystal (PC) surface-emitting lasers (SELs) or PCSELs, utilizing band-edge effect of a two-dimensional (2D)-PC structure, possess the advantages of single-mode operation, high optical output, narrow beam divergence and excellent beam quality [1,2,3,4,5]
We demonstrate optically pumped QD PCSELs with bottom GaAs/AlGaAs distributed Bragg reflector (DBR)
After removing the top DBR, the sample without PC patterning was characterized at room temperature (RT) by

Summary

Introduction

Photonic-crystal (PC) surface-emitting lasers (SELs) or PCSELs, utilizing band-edge effect of a two-dimensional (2D)-PC structure, possess the advantages of single-mode operation, high optical output, narrow beam divergence and excellent beam quality [1,2,3,4,5]. 2D-PCs to construct the cavity mode where in-plane distributed feedback (DFB) diffracts vertically [1]. The cavity mode is achieved over a large lasing area with single longitudinal and transverse mode oscillations. As in-plane optical feedback diffracts both upward and downward, the intuitive approach to harvest light output is to reflect downward emissions by bottom distributed Bragg reflector (DBR). Prior publication of violet PCSELs with bottom GaN/AlN DBR claimed to have higher top-emission efficiency when lasing wavelengths are in the stopband of DBR [2].

Methods

Discussion

Conclusion