'Saser' claimed as next step for laser

Scientists at Nottingham University, in collaboration with colleagues at the Lashkarev Institute of Semiconductor Physics in the Ukraine, have produced the saser, a sonic equivalent to the laser.

In operation, the saser device is comprised of a man-made structure called a ‘superlattice’, composed of around 50 sheets of two alternating layers of gallium arsenide and aluminium arsenide, semiconductor materials just a few atoms thick.

In an interview with The Engineer Online, Prof Anthony Kent, from the university’s school of physics and astronomy, explained that a light beam can be used to excite electrons in these semiconductor materials into a high energy state, energy they can then lose through the process of phonon emission.

‘What happens in our saser is similar to the way a laser works: a few excited electrons relax and lose their energy and momentum spontaneously through the emission of a phonon.

‘The emitted phonons are ‘trapped’ in a cavity, or superlattice, and then go on to stimulate further emissions by excited electrons,’ he said.

This process of coherent amplification leads to the generation of the saser beam.

Crucially, the ‘superlattice’ device can be used to generate, manipulate and detect soundwaves in the terahertz frequency range, making it useful in a range of scientific and technological applications.

‘While our work on sasers is driven mostly by pure scientific curiosity, we feel that the technology has the potential to transform the area of acoustics, much as the laser has transformed optics in the 50 years since its invention,’ Kent added.

The research team at Nottingham has won a grant of £636,000 from the Engineering and Physical Sciences Research Council to further develop the saser technology over the next four years.

David Wilson