A Sonic Boom In The World Of Lasers:
It was an idea born out of curiosity in the physics lab, but now a new type of ‘laser’ for generating ultra-high frequency sound waves instead of light has taken a major step towards becoming a unique and highly useful 21st century technology.Microwave Scientists at The University of Nottingham, in collaboration with colleagues in the Ukraine, have produced a new type of acoustic laser device called a Saser. It’s a sonic equivalent to the laser and produces an intense beam of uniform sound waves on a nano scale.
The new device could have significant and useful applications in the worlds of computing, imaging, and even anti-terrorist security screening. Where a ‘laser’,(Light Amplification by the Stimulated Emission of Radiation), uses packets of electromagnetic vibrations called ‘photons’, the ‘Saser’ uses sound waves composed of sonic vibrations called ‘phonons’.
In a laser, the photon beam is produced by stimulating electrons with an external power source so they release energy when they collide with other photons in a highly reflective optical cavity. This produces a coherent and controllable shining beam of laser light in which all the photons have the same frequency and rate of oscillation. From supermarket scanners to DVD players, surgery, manufacturing and the defence industry, the application of laser technology is widespread.
The Saser mimics this technology but using sound, to produce a sonic beam of ‘phonons’ which travels, not through an optical cavity like a laser, but through a tiny manmade structure called a ‘superlattice’. This is made out of around 50 super-thin sheets of two alternating semiconductor materials, Gallium Arsenide and Aluminium Arsenide, each layer just a few atoms thick. When stimulated by a power source (a light beam), the phonons multiply, bouncing back and forth between the layers of the lattice, until they escape out of the structure in the form of an ultra-high frequency phonon beam.
