# Enhancement of Electro-Optical Characteristics in GaN-Based Ultraviolet Laser Diodes Through Upper Optical Confinement Structure Design

## TL;DR

This paper shows how adjusting the upper cladding layer in UV laser diodes can reduce losses and improve performance.

## Contribution

A novel composite upper cladding layer design is proposed to optimize electro-optical characteristics in GaN-based UV laser diodes.

## Key findings

- Using a u-AlGaN and p-AlGaN composite cladding layer reduces internal absorption loss.
- Thinner u-AlGaN layers improve performance in devices with thick waveguide layers.
- Thicker u-AlGaN layers are better for devices with thin waveguide layers to suppress absorption loss.

## Abstract

Two series of laser diodes with different AlGaN cladding layers were investigated, and it was found that the internal absorption loss was reduced by using a u-AlGaN and p-AlGaN composite upper cladding layer, and the performance of LD was improved. The optimized thickness of u-AlGaN is related to the waveguide layer structure of LDs. For LDs with a thick waveguide layer, the u-AlGaN cladding layer should be thinner to achieve high hole concentration and high hole injection efficiency. For LDs with a thin waveguide layer, the u-AlGaN cladding layer can be thick to suppress the internal absorption loss. Thus, a composite upper waveguide structure with a thinner waveguide layer, a thicker u-AlGaN cladding layer, and a p-AlGaN cladding layer is an optimized structure for short waveguide UV LDs due to lower carrier loss and absorption loss.