Sound Amplification by Stimulated Emission of Radiation
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A SASER is the acoustic analogue of the laser. It is capable of producing highly coherent, concentrated beams of ultrasound, using methods very similar to those employed in the laser. Though currently only theoretical, the SASER is being developed at the University of Nottingham and the Lashkarev Institute of Semiconductor Physics.
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[edit] Physics
A SASER operates on principles remarkably similar to those of a laser. A stack of thin semiconductor wafers are placed in a lattice within an acoustically reflective chamber. Upon the addition of electrons, short-wavelength (in the Terahertz range) phonons are produced. Since the electrons are confined to the quantum wells existing within the lattice, the transmission of their energy depends upon the phonons they generate. As these phonons strike other layers in the lattice, they excite electrons, which produce further phonons, which go on to excite more electrons, and so on. Eventually, a very narrow beam of high-frequency ultrasound exits the device.
[edit] Uses
Apart from allowing the investigation of terahertz-frequency ultrasound, the SASER is also likely to find a myriad of uses in optoelectronics, as a method of signal modulation and/or transmission. [1]
