Internal-loss-limited 5.5% wall-plug efficiency in index-guided AlGaN UV-B laser diodes with polarization-doped cladding layers

Rintaro Miyake; Takumu Saito; Shion Kamiya; Ryota Watanabe; Yuma Miyamoto; Seiya Kato; Naoki Kitta; Rintaro Kobayashi; Tomoya Tanikawa; Kenta Kitagawa; Sho Iwayama; Hideto Miyake; Tetsuya Takeuchi; Satoshi Kamiyama; Motoaki Iwaya

doi:10.1063/5.0341819

Internal-loss-limited 5.5% wall-plug efficiency in index-guided AlGaN UV-B laser diodes with polarization-doped cladding layers

R Rintaro Miyake (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) T Takumu Saito (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) S Shion Kamiya (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) R Ryota Watanabe Y Yuma Miyamoto (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) S Seiya Kato N Naoki Kitta (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) R Rintaro Kobayashi (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) T Tomoya Tanikawa (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) K Kenta Kitagawa (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) S Sho Iwayama (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) H Hideto Miyake T Tetsuya Takeuchi (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) S Satoshi Kamiyama (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,) M Motoaki Iwaya (Department of Materials Science and Engineering, Meijo University 1 , Nagoya 468-8502,)

Abstract

This study identifies the dominant factor governing wall-plug efficiency (WPE) in AlGaN-based UV-B laser diodes. While previous studies have mainly focused on optical confinement, the limiting mechanism has remained unclear. Here, we investigate index-guided ridge waveguide laser diodes and systematically analyze the relationship between internal optical loss (αi) and device performance. Index-guided operation is confirmed by effective index simulations and near-field measurements. We find that device performance is governed primarily by αi rather than optical confinement. By minimizing αi, the threshold current is reduced, and the slope efficiency is improved, leading to a maximum WPE of 5.5% in an uncoated device. These results reveal that reducing αi, rather than enhancing optical confinement, is the key design principle for improving WPE in AlGaN-based UV-B laser diodes.

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Article Details

Journal Applied Physics Letters

Volume / Issue Vol. 129, Issue 5

Published August 03, 2026

DOI 10.1063/5.0341819

ISSN 0003-6951

Publisher American Institute of Physics

Journal Info

Applied Physics Letters

American Institute of Physics

ISSN: 0003-6951 Physical Sciences