Deep-UV optical gain in AlGaN-based graded-index separate confinement heterostructure

Emanuele Francesco Pecora,Theodore D Moustakas,Luca Dal Negro,Haiding Sun

doi:10.1364/ome.5.000809

Abstract

We propose AlGaN-based GRaded-INdex Separate Confinement Heterostructure as a candidate for electrically pumped deep-UV semiconductor laser. Strong compositional fluctuations were introduced in the active region (75 nm-thick Al0.72Ga0.28N film grown by RF Plasma- assisted Molecular Beam Epitaxy) to obtain net modal optical gain peaked at 257 nm in excess of 80 cm −1 . We measured an optical gain threshold of 14 µJ/cm 2 . Because of polarization-doping of the compositionally graded AlGaN regions, which automatically leads to the formation of p-i-n junction, these results pave the way for lasing under electrical injection.

Highlights

The demonstration of a compact, portable, solid-state deep-UV laser is strongly required to enable a number of applications in different fields, such as non-line-of-sight free-space optical communications, biochemical agent detection, disinfection, and medical diagnostics
Semiconductor laser designs have evolved extensively over the last few decades targeting lower lasing thresholds with higher gain efficiency. These important performance indicators were demonstrated via several architectural improvements, which include the Separate Confinement Heterostructure (SCH) laser, the quantum well SCH, and the GRaded-INdex SCH (GRINSCH) geometry [29,30,31]
We report the development of an AlGaN-based deep-UV laser structure in the form of a GRaded INdex Separate Confinement Heterostructure (GRINSCH), which is capable of better carrier and optical confinement

Summary

Introduction

The demonstration of a compact, portable, solid-state deep-UV laser is strongly required to enable a number of applications in different fields, such as non-line-of-sight free-space optical communications, biochemical agent detection, disinfection, and medical diagnostics. An alternative approach consists in the design of a laser structure capable of enhancing both the carrier and the optical confinement factors in the active region. Semiconductor laser designs have evolved extensively over the last few decades targeting lower lasing thresholds with higher gain efficiency. These important performance indicators were demonstrated via several architectural improvements, which include the Separate Confinement Heterostructure (SCH) laser, the quantum well SCH, and the GRaded-INdex SCH (GRINSCH) geometry [29,30,31]. The GRINSCH design efficiently confines carriers and enhances the optical confinement factor [29,30,31,32]

Methods

Findings

Discussion

Conclusion