A research group led by 2014 Nobel Prize laureate Hiroshi Amano at the Institute for Materials and Systems for Sustainability (IMaSS) at Nagoya University in central Japan, in collaboration with Asahi Kasei, has successfully performed the world’s first room-temperature continuous-wave laser process. – Multi-beam laser diode (wavelengths down to the UV-C region).
These results have been published in Applied Physics Lettersrepresents a step toward widespread use of a technology that has the potential for a wide range of applications, including sterilization and medicine.
Since their introduction in the 1960s, and after decades of research and development, successful commercialization of laser diodes (LDs) has finally been achieved for a number of wavelength applications ranging from infrared to blue-violet. Examples of this technology include optical communication devices with infrared LDs and Blu-ray discs with blue-violet LDs.
However, despite the efforts of research groups around the world, no one has been able to develop deep ultraviolet LDS. A major breakthrough occurred only after 2007 with the advent of technology to fabricate aluminum nitride (AlN) substrates, an ideal material for growing aluminum gallium nitride (AlGaN) film for ultraviolet light emitting devices.
Starting in 2017, the research group of Professor Amano, in collaboration with Asahi Kasei, the company that provided the 2-inch AlN substrates, began developing deep UV LD. Initially, injecting sufficient current into the device was very difficult, which prevented further development of UV-C laser diodes.
But in 2019, the research group successfully solved this problem by using the polarization-induced doping technique. For the first time, they produced short-wavelength ultraviolet (UV-C) LD that acted with short current pulses. However, the input power required for these current pulses was 5.2 W. This was too high for a continuous wave laser because the energy would cause the diode to quickly heat up and turn off the laser.
But now, researchers from Nagoya University and Asahi Kasei have reconfigured the structure of the device itself, reducing the motor power needed to power the laser at just 1.1 watts at room temperature. Previous devices have been found to require high levels of operational power due to the inability of effective current paths due to crystalline defects that occur in the laser band. But in this study, the researchers found that strong crystalline strain creates these defects.
Through intelligent sewing of the sidewalls of the laser strip, they suppress defects, achieve efficient current flow to the active region of the laser diode and reduce operating power.
Nagoya University’s academic and industry collaboration platform, called the Integrated Research Center for Future Electronics, Transformational Electronics Facilities (C-TEFs), has made possible the development of the new ultraviolet laser technology. Under C-TEFs, researchers from partners such as Asahi Kasei share access to state-of-the-art facilities on the Nagoya University campus, providing them with the people and tools needed to build high-quality, reproducible devices.
Zhang Ziyi, a representative of the research team, was in his sophomore year at Asahi Kasei when he co-founded the project. “I wanted to do something new,” he said in an interview. “At the time, everyone assumed that the ultraviolet laser diode was impossible, but Professor Amano told me, ‘We’ve come to the blue laser, and now it’s time for the UV’.”
This research is a milestone in the practical application and development of semiconductor lasers in all wavelength ranges. In the future, UV-C LDs can be applied in healthcare, virus detection, particle measurement, gas analysis, and high-precision laser processing.
“Its application to sterilization technology could be groundbreaking,” Zhang said. “Unlike current disinfection methods with LEDs, which are time-inefficient, lasers can disinfect large areas in a short time and over long distances.” This technology could particularly benefit surgeons and nurses who need sterile operating rooms and tap water.
Successful results have been reported in two papers Applied Physics Letters.
Hiroshi Amano et al., Local stress control to suppress dislocation generation for pseudo-implanted AlGaN UV-C laser diodes, Applied Physics Letters (2022). DOI: 10.1063 / 5.0124512
Hiroshi Amano et al., Main temperature-dependent properties of an AlGaN-based UV-C laser diode and showing room temperature continuous wave lasers, Applied Physics Letters (2022). DOI: 10.1063 / 5.0124480
Provided by Nagoya University
the quote: Scientists Demonstrate World’s First Continuous Wave Deep Ultraviolet Laser Diode at Room Temperature (2022, November 24) Retrieved November 24, 2022 from https://phys.org/news/2022-11-scientists- world-continuous-wave-lasing-deep-ultraviolet.html
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