Compact Blue Laser Enables Far-UV Light Source for Disinfection

Researchers at Osaka University have achieved a significant breakthrough by developing the world’s first compact, tunable-wavelength blue semiconductor laser, marking a major step forward in far-ultraviolet light technology. This advancement holds immense potential for sterilization and disinfection applications. The study was published in the journal Applied Physics Express.

The laser features a uniquely designed periodically slotted structure within nitride semiconductors, enabling a practical and adaptable blue-wavelength laser suitable for various disinfection technologies.

The team had previously achieved second-harmonic generation at wavelengths below 230 nm using transverse quasi-phase-matching devices made from aluminum nitride and vertical microcavity wavelength conversion devices incorporating SrB₄O₇ nonlinear optical crystals. These advanced devices typically required large, expensive ultrashort-pulse lasers as excitation sources. However, a practical far-ultraviolet light source requires a blue semiconductor laser with a wavelength of around 460 nm.

Originally developed for Blu-ray applications, blue nitride semiconductor lasers have since been used in processing metallic materials like copper and gold, with potential applications in next-generation laser displays.

However, these lasers typically oscillate at multiple wavelengths, which is incompatible with high-efficiency wavelength conversion devices due to their narrow wavelength acceptance bandwidth. Single-wavelength lasers are therefore preferred as excitation sources, with precise wavelength control and tunability being essential. While some single-wavelength blue lasers with coarse periodic structures have been developed, none have yet offered tunable wavelength control.

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. Combined with our new wavelength conversion devices, this laser enables the creation of a compact, practical far-ultraviolet light source that is safe for continuous use in indoor environments, providing effective and ongoing sterilization and disinfection.

Taisei Kusui, Study First Author, Osaka University

With its compact design and long lifespan, this technology is ideal for integration into household appliances such as refrigerators and air conditioners. Its adoption could improve public health by fostering safer and healthier living environments.

Journal Reference:

Kusui, T., et al. (2024) Continuous-wave operation of InGaN tunable single-mode laser with periodically slotted structure. Applied Physics Express. doi.org/10.35848/1882-0786/ad66ab.