Ultraviolet-C Vertical-Cavity Surface-Emitting Lasers with Precise Cavity Length Control
Journal article, 2025
In vertical-cavity surface-emitting lasers (VCSELs), the cavity length defines the resonance wavelength, which is directly related to the laser detuning, that is, the difference between resonance wavelength and gain peak. A low detuning maximizes the modal gain leading to a reduction of the threshold. Therefore, controlling the cavity length of VCSELs is of great importance. Here optically pumped ultraviolet-C (wavelength (Formula presented.) 280 nm) VCSELs with precise cavity length control are demonstrated. The VCSEL structure is formed by an AlN cavity with 5 (Formula presented.) Al0.40Ga0.60/Al0.70Ga0.30N quantum wells and a top HfO2 spacer layer with dielectric SiO2/HfO2 distributed Bragg reflectors on both sides of the cavity. To access the N-face side of the cavity, a new methodology referred to as photo-assisted electrochemical etching is employed for substrate removal. Across a 0.9 mm (Formula presented.) 1.2 mm area, the lasing wavelength varies a maximum of 1.17 nm between different UVC VCSELs, exhibiting threshold pump power densities from 0.7 MW/cm2 to 3.7 MW/cm2 and detuning values between 0 to 2 nm. The results show that VCSELs with a cavity length variation lower than 1 (Formula presented.) can be obtained with this technology.
UVC
VCSEL
photo-assisted electrochemical etching
AlGaN
electrochemical etching
Author
Estrella Torres
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Joachim Ciers
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Nelson Rebelo
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Filip Hjort
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Michael Alexander Bergmann
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Sarina Graupeter
Technische Universität Berlin
Johannes Enslin
Ferdinand-Braun-Institut fur Hochstfrequenztechnik
Technische Universität Berlin
Giulia Cardinalli
Technische Universität Berlin
Tim Wernicke
Technische Universität Berlin
Michael Kneissl
Technische Universität Berlin
Ferdinand-Braun-Institut fur Hochstfrequenztechnik
Åsa Haglund
Chalmers, Microtechnology and Nanoscience (MC2), Photonics
Laser and Photonics Reviews
1863-8880 (ISSN) 1863-8899 (eISSN)
Vol. In PressMicrocavity laser breakthrough for ultraviolet light (UV-LASE)
European Commission (EC) (EC/H2020/865622), 2020-08-01 -- 2025-07-31.
Ultravioletta och blå mikrokavitetslasrar
Swedish Research Council (VR) (2018-00295), 2019-01-01 -- 2024-12-31.
Subject Categories (SSIF 2025)
Atom and Molecular Physics and Optics
Telecommunications
Subatomic Physics
Infrastructure
Myfab (incl. Nanofabrication Laboratory)
DOI
10.1002/lpor.202402203