R&D project targets thin-disk lasers

07 Oct 2005

The development of UV and visible VECSEL devices receives a EURO 3.8 million boost thanks to an EC initiative.

High-power, visible and ultraviolet VECSEL technology could soon find its way into materials processing, medical and display applications if a EURO 3.8 million project supported by the European Commission (EC) is successful. Dubbed NATAL, the three year project is coordinated by Optical Research Center, Finland, who together with the University of Strathclyde, UK, developed a 390 mW red VECSEL earlier this year (External cavity VCSEL goes visible, January 2005).

"Currently, gas lasers and solid-state lasers suffer from inefficient, expensive and complex setups, which have hampered their use as high-power visible and ultraviolet light sources in high volume markets," Wilhelm Kaenders of Toptica, a NATAL partner, told Optics.org. "[Although] recently developed fiber lasers are very attractive for many applications, their emission wavelength is limited by the range of available gain fibers."

The NATAL team, which also includes Chalmers University of Technology, Sweden, and Technical University of Berlin, Germany, is pooling its expertise to accelerate the development of an alternative technology - the so-called optically-pumped vertical external cavity surface-emitting semiconductor laser (OP-VECSEL).

"These exciting new sources are emerging at the boundary between conventional diode-pumped solid-state lasers and electrically-pumped semiconductor lasers, combining many of the advantages of both," said Kaenders. "However, so far they have seen little development outside of the ~1 µm infrared wavelength region."

The project addresses three key areas - the development of nano-structured gain devices, the use of micro-optical elements to control the laser cavity and the exploration of potential applications.

With OSRAM, EpiCrystals and OptoCap , joining Toptica as industrial partners, NATAL has a strong commercial focus. High-power, red VECSELs are top of the team's wish list, for applications such as holography, absolute distance interferometry, confocal Raman spectroscopy and high-speed data storage.

Along with direct operation in the red (630-670 nm), specific wavelength goals include the development of frequency-doubled VECSELs operating at 315-335 nm, 470 nm, 520 nm and 610 nm. For example, blue and green devices would provide the primary colors for RGB displays.

NATAL is due to report its first results at the end of the year and Kaenders says that we could soon see visible devices with output powers approaching 1 W.