Compact lasers which can work in formerly inaccessible parts of
the spectrum and are suitable for mass production are now within
reach, thanks to pioneering work by a European consortium.
Digital projectors use a variety of technologies to throw an
image on to a screen. But existing projectors are bulky and
there is a growing commercial interest in using new laser
technology to make a projector small enough to build into a
laptop computer or even a mobile phone. “Such devices would have
extremely high market potential,” says Mircea Guina of Tampere
University’s Optoelectronics Research Centre. “But so far the
development has been technologically hindered by the ‘green gap’
– the lack of green laser diodes.” Laser diodes are very
compact, mass producible and relatively cheap. They are widely
used in such common devices as barcode readers, CD players and
laser pointers. The standard approach uses so-called ‘edge-
emitting’ diodes that offer a restricted range of visible
wavelengths, which has proven to be techno