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Deep-UV Photonic Crystal Surface-Emitting Lasers

D. Apaydın1, H. Andersson2, L. Uhlig3, S. Graupeter4, J. Ciers1, G. Cardinali4, E. Strandberg1, T. Wernicke4, M. Kneissl4,5, U.T. Schwarz3, P. Tassin2, and Å. Haglund1

Published in:

Laser Photonics Rev., vol. 20, no. 6, pp. e00271, doi:10.1002/lpor.202500271 (2026).

Abstract:

Today's ultraviolet lasers are bulky, expensive, have low power-conversion efficiency, and usually suffer from poor beam quality. Semiconductor lasers have addressed these issues in the visible and infrared parts of the electromagnetic spectrum; but in the ultraviolet, they are just starting to see the light of day. Edge-emitting semiconductor lasers are the only ones demonstrated under electrical injection in the deep-ultraviolet (λ<280 nm) and they inherently suffer from poor beam qualities, multiple modes, and catastrophic optical damage to the mirror. The first deep-UV photonic crystal surface-emitting lasers are demonstrated here. The devices show single-mode emission around 279 nm with less than 1° beam divergence. They require a specific design to overcome optical scattering and the low refractive index that otherwise prohibits a 2D standing optical field. The optically pumped deep-ultraviolet photonic crystal surface-emitting lasers offer drastically improved beam quality and provide an important step toward low-divergent, watt-class, electrically-driven UV PCSELs.

1 Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg 41296, Sweden
2 Department of Physics, Chalmers University of Technology, Gothenburg 41296, Sweden
3 Institute of Physics, Chemnitz University of Technology, 09126 Chemnitz, Germany
4 Institute of Solid State Physics, Technische Universität Berlin, 10623 Berlin, Germany
5 Ferdinand-Braun-Institut, 12489 Berlin, Germany

Keywords:

AlGaN, filling factor, low divergence, photonic crystal surface-emitting laser (PCSEL), UV-C

© 2025 The Author(s). Laser & Photonics Reviews published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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