Article
Nanoscience & Nanotechnology
Rami T. Elafandy, Jin-Ho Kang, Chenziyi Mi, Tae Kyoung Kim, Joon Seop Kwak, Jung Han
Summary: This paper introduces a technique using birefringent nanoporous DBRs to achieve polarization locking in GaN VCSELs, overcoming the challenge of laser polarization control, demonstrating a fully electrically injected blue VCSEL. This technique allows the definition of polarization angles in a planar array, opening up possibilities for novel applications.
Article
Engineering, Electrical & Electronic
Kentaro Hayashi, Tatsushi Hamaguchi, Jared A. Kearns, Noriko Kobayashi, Maho Ohara, Tomohiro Makino, Shoetsu Nagane, Koichi Sato, Yuki Nakamura, Yukio Hoshina, Tatsuro Jyoukawa, Takumi Watanabe, Yuichiro Kikuchi, Maiko Ito, Eiji Nakayama, Rintaro Koda, Noriyuki Futagawa
Summary: We report a blue gallium-nitride-based visible vertical-cavity surface-emitting laser (GaN-VCSEL) with a narrow divergence angle achieved by using a curved mirror. The device exhibited continuous-wave operation and the divergence angle was found to be dependent on the radius of curvature (ROC) of the mirror.
IEEE PHOTONICS JOURNAL
(2022)
Article
Physics, Applied
Jared A. Kearns, Tatsushi Hamaguchi, Kentaro Hayashi, Maho Ohara, Tomohiro Makino, Maiko Ito, Noriko Kobayashi, Tatsurou Jyoukawa, Eiji Nakayama, Shoetsu Nagane, Koichi Sato, Yuki Nakamura, Yukio Hoshina, Rintaro Koda, Noriyuki Futagawa
Summary: A single cavity filtering mirror was used to achieve single longitudinal mode operation for a VCSEL with a 25 mu m cavity length. The increase in DBR pairs between the VCSEL and filtering mirror cavity reduced the optical standing wave and resulted in an improved slope efficiency and output power.
APPLIED PHYSICS EXPRESS
(2022)
Article
Physics, Applied
Maiko Ito, Tatsushi Hamaguchi, Tomohiro Makino, Kentaro Hayashi, Jared A. Kearns, Maho Ohara, Noriko Kobayashi, Shoetsu Nagane, Koichi Sato, Yuki Nakamura, Yukio Hoshina, Tatsurou Jyoukawa, Takumi Watanabe, Yuichiro Kikuchi, Seiji Kasahara, Susumu Kusanagi, Yuya Kanitani, Yoshihiro Kudo, Eiji Nakayama, Rintaro Koda, Noriyuki Futagawa
Summary: This study achieved high uniformity and efficiency in GaN-based vertical-cavity surface-emitting lasers with curved mirrors from a single wafer. The average threshold current (I (th)) and optical output power (P (max)) of 14 chips were measured to be 0.64 mA and 4.5 mW, respectively, with standard deviations of 6.7% and 5.1%, respectively. Furthermore, the best chip exhibited maximum wall plug efficiency and output power of 13.4% and 7.6 mW, respectively, at operating currents of 5.2 mA and 12.8 mA.
APPLIED PHYSICS EXPRESS
(2023)
Article
Optics
Kuo-Bin Hong, Tsu-Chi Chang, Filip Hjort, Niclas Lindvall, Wen-Hsuan Hsieh, Wei-Hao Huang, Po-Hsun Tsai, Tomasz Czyszanowski, Asa Haglund, Tien-Chang Lu
Summary: This paper presents a pulsed electrically pumped GaN-based vertical-cavity surface-emitting laser (VCSEL) at room temperature, with an n-GaN monolithic high-index contrast grating (MHCG) mirror. Experimental results show that lasing action begins at an injection current of 10.2 mA and the use of an n-GaN MHCG mirror significantly improves laser characteristics compared to previous work.
PHOTONICS RESEARCH
(2021)
Proceedings Paper
Engineering, Electrical & Electronic
Tatsushi Hamaguchi, Maiko Ito, Jared A. Kearns, Tomohiro Makino, Kentaro Hayashi, Maho Ohara, Noriko Kobayashi, Tatsuro Jyokawa, Eiji Nakayama, Shouetsu Nagane, Koichi Sato, Yuki Nakamura, Yukio Hoshina, Yuichiro Kikuchi, Takumi Watanabe, Yuya Kanitani, Seiji Kasahara, Yoshihiro Kudo, Susumu Kusanagi, Rintaro Koda, Noriyuki Fuutagawa
Summary: This article reports the latest progress in gallium nitride-based vertical-cavity surface-emitting lasers (VCSELs) with a curved mirror. Highly uniform and efficient devices have been developed. The average threshold current was 0.64 mA with a standard deviation of 0.043 mA. Peak wall-plug efficiency and output power were 13.4% and 7.6 mW at operating currents of 5.2 mA and 12.8 mA, respectively. Green VCSELs with milliwatt-class outputs and a wall-plug efficiency of 3.7% were achieved. The progress of VCSELs with a single-cavity filtering mirror and a cavity length of approximately 25 μm, showing highly varying reflectivity spectra, to demonstrate their single-longitudinal mode operation, is also reported.
GALLIUM NITRIDE MATERIALS AND DEVICES XVIII
(2023)
Article
Optics
Nathan C. Palmquist, Ryan Anderson, Jared A. Kearns, Joonho Back, Emily Trageser, Stephen Gee, Steven P. Denbaars, Shuji Nakamura
Summary: This article reports GaN-based vertical-cavity surface-emitting lasers with a long cavity of 60.5λ, a topside monolithic GaN concave mirror, a buried tunnel junction current aperture, and a bottomside nanoporous GaN distributed Bragg reflector. Under pulsed operation, a VCSEL with a 9 μm aperture had a threshold current density of 6.6 kA/cm(2), a differential efficiency of 0.7%, and a maximum output power of 290 μW for a lasing mode at 411 nm and a divergence angle of 8.4°. Under CW operation, the threshold current density increased to 7.3 kA/cm(2), the differential efficiency decreased to 0.4%, and a peak output power of 130μW was reached at a current density of 23 kA/cm(2).
Article
Chemistry, Multidisciplinary
Jinyuan Xu, Ailing Chen, Linfeng Yu, Donghai Wei, Qikun Tian, Huimin Wang, Zhenzhen Qin, Guangzhao Qin
Summary: In this paper, the stable structure of a monolayer CuI with ultra-low thermal conductivity and an ultra-wide direct bandgap is predicted from first-principles calculations. This material shows potential applications in transparent and wearable electronics.
Article
Optics
Pallabi Das, Kasturi Saha, Siddharth Tallur
Summary: This paper proposes a design platform to achieve large anomalous dispersion in vertically coupled GaN/AlN/GaN waveguides on commercially available GaN template wafers, with results showing anomalous dispersion as large as 1.83x10^5 ps (nm-km)(-1). Numerical simulations demonstrate efficient Kerr frequency comb generation in the blue spectral range, and tailoring geometric parameters of the waveguides can induce asymmetrical spectral profiles in the comb due to higher-order dispersion.
Article
Physics, Applied
B. Ding, J. Jarman, M. J. Kappers, R. A. Oliver
Summary: By using STEM analysis, it was found that InGaN samples grown at lower temperatures exhibit microscale variations in the green-emitting surface, with brighter regions showing high density of gross-well width fluctuations, while dimmer regions have a more uniform thickness of InGaN QWs.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Junting Chen, Junlei Zhao, Sirui Feng, Li Zhang, Yan Cheng, Hang Liao, Zheyang Zheng, Xiaolong Chen, Zhen Gao, Kevin J. J. Chen, Mengyuan Hua
Summary: In this study, the GaN surface is converted into a GaON epitaxial nanolayer through a two-step oxidation-reconfiguration process, overcoming the vulnerability of the GaN surface and enhancing the stability and reliability of GaN-based devices. The GaON nanolayer derived from GaN possesses advantages such as a wide bandgap, high thermodynamic stability, and large valence band offset with a GaN substrate, which can be further utilized to improve the performance of GaN-based devices in various applications.
ADVANCED MATERIALS
(2023)
Article
Optics
Xizheng Ke, Shangjun Yang, Yu Sun, Jingyuan Liang, Xiya Pan
Summary: In this study, a design scheme for a double-layered compound eye lens optical system with wide-angle focusing was proposed for underwater optical wireless communication systems. Experimental and simulation results demonstrated that the double-layered compound eye system achieved higher optical power reception compared to the single-layered system, indicating its strong practicality and potential in the field.
Article
Engineering, Electrical & Electronic
Marco Malinverni, Antonino Castiglia, Marco Rossetti, Adin Ferhatovic, Denis Martin, Marcus Duelk, Christian Velez
Summary: This report presents the results of short cavity single transverse mode LDs with n-type InAlN cladding layers. The threshold currents for blue and green light are demonstrated to be 3.3 and 12.0 mA, respectively, with low electrical power consumption at mW range optical powers. Compared to conventional AlGaN-based devices with the same active regions, an increase in modal gain is observed, resulting in approximately 25% reduction in threshold currents. The improvement in modal gain can be attributed to a higher optical confinement factor when using InAlN.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Yahya Mohtashami, Larry K. Heki, Matthew S. Wong, Jordan M. Smith, Jacob J. Ewing, William J. Mitchell, Shuji Nakamura, Steven P. DenBaars, Jon A. Schuller
Summary: Researchers demonstrate metasurface LEDs that emit directional or focused light, showing advanced phase control technology. These metasurface LEDs exhibit better external quantum efficiency than unpatterned LEDs, providing possibilities for the development of high-efficiency metal-free LED devices.
Article
Engineering, Electrical & Electronic
Muhammad Saddique Akbar Khan, Hui Liao, Guo Yu, Imran Iqbal, Menglai Lei, Rui Lang, Zehan Mi, Huanqing Chen, Hua Zong, Xiaodong Hu
Summary: Two innovative techniques, serpentine channel pattern sapphire substrate (SCPSS) and InGaN interlayer (IL), are proposed to effectively reduce threading dislocations (TDs) in GaN-based devices. Experimental results demonstrate the effectiveness of these techniques in decreasing the number of TDs and improving material quality.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
