GaN-based vertical-cavity surface-emitting lasers (VCSELs) are promising for displays, sensing, and optical communication, but improving efficiency remains challenging. Researchers have now shown that “cavity tuning,” which controls resonance wavelength, strongly affects laser performance. By analyzing variations across a VCSEL wafer, the team identified optimal mirror loss conditions and extracted device parameters. Their approach achieved 26.4% wall plug efficiency, offering guidance for next-generation high-efficiency visible-light semiconductor lasers.
Gallium Nitride (GaN)-based vertical-cavity surface-emitting lasers, or VCSELs, are attracting increasing attention as compact and energy-efficient light sources for future technologies. These semiconductor lasers are considered promising for applications such as next-generation displays, biometric sensing, environmental monitoring, and short-range optical communication. However, improving their efficiency has remained a major challenge because laser performance depends strongly on precise optical design and cavity control.
Addressing this challenge, a research team led by Professor Tetsuya Takeuchi, Professor Satoshi Kamiyama, and Professor Motoaki Iwaya from the Department of Materials Science and Engineering, Meijo University, Japan, along with Mr. Naoki Shibahara, first author and graduate student at the Graduate School of Science and Technology, Meijo University, Japan, investigated how “cavity tuning” influences the lasing characteristics of GaN-based VCSELs. While conventional studies mainly focused on gain tuning, also known as detuning, the researchers demonstrated that resonance wavelength alignment relative to the distributed Bragg reflector center wavelength critically affects laser operation. Their research was published in Volume 128, Issue 17 of Applied Physics Letters on April 27, 2026, and made available online on April 30, 2026.
The researchers studied GaN-based VCSEL wafers containing AlInN/GaN distributed Bragg reflectors, which possess a relatively narrow optical stop band. Because of this narrow range, even small shifts in resonance wavelength can significantly change mirror loss and influence laser efficiency. By examining in-plane variations across the wafer, the team observed how cavity tuning systematically altered mirror loss values from 25 to 50 cm −1 . They then correlated these changes with important laser characteristics, including differential external quantum efficiency, threshold current density, and wall-plug efficiency.
Their measurements showed that cavity tuning provided valuable insight into internal device physics that conventional detuning analysis alone could not explain. By analyzing the mirror loss dependence, the team extracted key internal parameters, including an injection efficiency of approximately 85% and an internal loss near 11 cm −1 . Importantly, they identified an optimal mirror loss region around 35–40 cm −1 , where wall-plug efficiencies above 25% could be achieved. The best-performing device demonstrated a wall-plug efficiency of 26.4%, exceeding the group’s previously reported performance.
“ What motivated this study was our observation of in-plane variations in laser characteristics,” explained Prof. Takeuchi. “ By measuring devices across the wafer and analyzing the data, we found that conventional gain detuning alone could not fully explain the results. This led us to identify the importance of cavity tuning.”
The findings could help accelerate the development of practical high-efficiency visible-light laser sources. Since GaN-based VCSELs are considered promising for compact photonic systems, the improved understanding of cavity tuning may support more reliable design strategies for commercial devices requiring high optical performance and energy efficiency.
“The observation of wall-plug efficiency exceeding 20%, which was among the highest levels reported worldwide at the time, strongly encouraged me to further advance my research on VCSEL characteristics ,” said Mr. Shibahara. He added that he is currently investigating two-dimensional VCSEL integration for high-power operation, focusing on device interactions, thermal and optical effects, and highly efficient array design.
Overall, the study demonstrates that cavity tuning is a critical design parameter in GaN-based VCSELs alongside conventional gain tuning. By transforming natural in-plane wafer variations into a research advantage, the team established a practical method for optimizing mirror loss and improving laser efficiency. The findings provide important guidance for the future design of high-performance semiconductor lasers for sensing, communication, and advanced photonic technologies.
About Meijo University
Meijo University traces its origin back to the establishment of the Nagoya Science and Technology Course in 1926, giving it a proud history of more than 90 years. As one of the largest universities in the Chubu region, Meijo University is a comprehensive learning institution that supports a wide range of academic fields from the humanities to the physical sciences. With a network of more than 200,000 graduates and alumni, it strives to contribute not only to local industries but also to international communities in various fields. Meijo University is also known as the birthplace of the carbon nanotube. To foster the human resources of the next generation, the university continues to tackle ongoing challenges by further enhancing its campus and creating new faculties.
Website: https://www.meijo-u.ac.jp/english/
About Professor Tetsuya Takeuchi from Meijo University
Professor Tetsuya Takeuchi is a Professor in the Department of Materials Science and Engineering at Meijo University, Japan. His research focuses on optoelectronic devices, including LEDs and lasers, developed using MOVPE growth techniques. He pioneered investigations into the optical properties of GaInN quantum wells with piezoelectric polarization charges and proposed growth on non-(0001) oriented substrates. He also demonstrated the first GaInN-based tunnel junction and the first GaN-based VCSEL using n-type conducting AlInN/GaN DBRs. Currently, his work includes in situ MOVPE monitoring, tunnel junctions, polarization doping, AlGaN-based deep-ultraviolet LEDs, and advanced GaN-based VCSEL technologies for future photonic applications.
About Naoki Shibahara from Meijo University
Mr. Naoki Shibahara is the first author and a graduate student at the Graduate School of Science and Technology, Meijo University, Japan. He is currently working on the two-dimensional integration of VCSELs for high-power operation, with particular interest in device interactions, and thermal and optical effects that are not significant in a single device, and array design for highly efficient operation.
Funding information
This work was supported by the JSPS KAKENHI for Scientific Research S (23H05460).
Applied Physics Letters
Experimental study
Not applicable
Impact of cavity tuning on lasing characteristics for GaN-based vertical-cavity surface-emitting lasers
30-Apr-2026