The world's first tunable wavelength blue semiconductor laser

Recently, researchers from Osaka University in Japan have developed the world's first compact, wavelength tunable blue semiconductor laser in a new study. This breakthrough paves the way for far ultraviolet light technology and brings enormous potential for applications such as virus inactivation and bacterial disinfection. The research results have been published in the journal Applied Physics Letters.

Figure 1 (a) Schematic diagram of a tunable single-mode laser with periodic slotted structure; (b) Cross sectional side view of slotted channel. Source: Taisei Kusui, Takumi Wada, Naritoshi Matsushita et al., "Continuous wave operation of InGaN tunable single mode laser with periodically slotted structure", Applied Physics Express (2024)

Researchers from Osaka University in Japan have previously demonstrated that a transverse quasi phase matching device made of aluminum nitride and a vertical microcavity wavelength conversion device containing SrB4O7 nonlinear optical crystals can generate far ultraviolet second harmonic (SHG) at wavelengths below 230 nm.

Usually, these advanced devices require large and expensive ultra short pulse lasers as excitation sources. However, achieving practical far ultraviolet light sources requires a blue semiconductor laser with a wavelength of approximately 460 nm.

Blue nitride semiconductor lasers were originally designed for blue light technology and have now expanded to the processing of metal materials such as copper and gold, with the potential to be applied in the next generation of laser display technology. However, the oscillation wavelengths of these blue light lasers are usually multiple.

Efficient wavelength conversion devices have a very narrow wavelength receiving bandwidth, making single wavelength lasers an ideal excitation source. In addition, precise wavelength control and adjustability are also essential. Although several single wavelength blue light lasers with coarse periodic structures have been reported, none of them can achieve tunable wavelength control.

Our tunable wavelength nitride semiconductor laser oscillates in the 405 nm wavelength band, but its structure can also be easily adjusted to 460 nm, "explained Kusui Taisei, the lead author of the research team." Combined with our new wavelength conversion device, this laser can create a compact and practical far ultraviolet light source suitable for continuous use in indoor environments, effectively sterilizing and disinfecting.

With its compact design and longer lifespan, this technology can be seamlessly integrated into household appliances such as refrigerators and air conditioners, providing healthier and safer living conditions for the home environment and bringing extensive benefits to public health.

Source: Yangtze River Delta Laser Alliance