In a groundbreaking study, scientists at Osaka University have developed the world’s first compact, tunable-wavelength blue semiconductor laser, marking a significant milestone in far-ultraviolet (UV) light technology. This innovative advancement holds immense promise for applications in sterilization and disinfection, providing a practical, scalable solution for enhancing public health and hygiene. The findings were recently published in the journal Applied Physics Express.
The new laser operates using a specially engineered periodically slotted structure in nitride semiconductors, enabling precise control over the laser’s wavelength. Unlike conventional systems, this design allows for a tunable blue laser that can be adapted to various applications, particularly in disinfection technologies that rely on far-ultraviolet light. Such lasers are critical for generating UV light efficiently, which is known to inactivate a wide range of pathogens, including bacteria and viruses.
The Osaka University team has an established track record in this field, having previously demonstrated advanced devices capable of second-harmonic generation at wavelengths below 230 nm. These achievements were made using transverse quasi-phase-matching devices constructed from aluminum nitride and vertical microcavity wavelength conversion devices that incorporated SrB4O7 nonlinear optical crystals. However, these earlier systems required large, expensive ultrashort-pulse lasers as excitation sources, limiting their practicality for widespread use.
To address this challenge, the researchers set out to develop a more compact and cost-effective blue semiconductor laser with a wavelength around 460 nm. This wavelength is particularly significant because it serves as an ideal excitation source for high-efficiency wavelength conversion devices, which have narrow wavelength acceptance bandwidths and work optimally with single-wavelength lasers. Existing blue nitride semiconductor lasers, initially designed for Blu-ray technology, have already found applications in processing metallic materials like copper and gold and are anticipated to play a role in next-generation laser displays. However, these lasers typically oscillate at multiple wavelengths, which limits their efficiency in applications requiring precise wavelength control.
The new laser by Osaka University overcomes these limitations by offering not only single-wavelength operation but also tunable wavelength control, a feature that has remained elusive in previous designs. “Our tunable-wavelength nitride semiconductor laser oscillates in the 405 nm band, but its structure can be readily adapted to the 460 nm band as well,” explained Taisei Kusui, the study’s first author. This flexibility is key to integrating the laser with advanced wavelength conversion devices, enabling the creation of compact and practical far-ultraviolet light sources.
One of the most remarkable aspects of this new technology is its potential for continuous use in indoor environments. Unlike traditional UV light sources, which can pose risks to human health, this compact laser system is safe for prolonged operation, making it suitable for various disinfection and sterilization applications. The far-UV light it generates is capable of deactivating pathogens on surfaces, in the air, and in water without causing harm to humans, paving the way for safer indoor environments.
The compact and robust design of this laser also makes it highly adaptable for integration into everyday appliances. With its extended lifespan and low maintenance requirements, the technology could be incorporated into household devices such as refrigerators, air conditioners, and air purifiers. This would provide a continuous, unobtrusive layer of disinfection, enhancing public health and safety in homes, offices, and public spaces.
The potential impact of this innovation extends beyond residential and commercial applications. In healthcare settings, where infection control is paramount, the laser could be used to sterilize medical instruments and facilities more efficiently. Similarly, its use in public transportation systems, schools, and other high-traffic areas could help curb the spread of infectious diseases.
By creating a compact, tunable-wavelength blue semiconductor laser, the Osaka University team has not only addressed key challenges in far-UV light generation but also opened new avenues for its application in a range of fields. This advancement promises to make sterilization and disinfection technologies more accessible, cost-effective, and practical, offering significant benefits for public health and safety worldwide.