Saser

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Saser is an acronym for Sound Amplification by Stimulated Emission of Radiation (sound amplification by stimulated emission of radiation). An incident sound wave is amplified with the help of an active medium, so that coherent sound waves arise in a delimited space. The SASER is therefore the acoustic counterpart to the laser .

development

The idea of ​​amplification of the sound analogous to that of a laser was pursued by various research groups as early as 2000. The main differences between the individual approaches lay mainly in the active medium used to amplify the sound .

The functionality of a SASER was proven for the first time by the Belarusian physicists IV Volkov, ST Zavtrak, and IS Kuten in 1997 at the Institute of Nuclear Problems in Minsk . They use liquids with enclosed gas bubbles as the active medium and a changing electric field for pumping.

In 2006, another group published the measurement of acoustically induced phonon emission. The simple structure of the amplifier medium is particularly worth mentioning, since it only consists of thin semiconductor layers.

functionality

The basic principle does not differ within the ASER family (laser, maser, SASER). Incident waves hit an active medium, in which they release further waves due to stimulated emission . In contrast to maser and laser, which are based on electromagnetic waves or photons , the SASER is about sound waves or phonons . The individual members of the ASER family also differ in the frequencies of the radiation used. A laser works with frequencies between 10 THz to 1 PHz, a maser from 100 kHz to 100 GHz and the SASER with 100 GHz to 1 THz. The SASER thus connects directly above the measles.

In the AJ Kent et al. In the work published in 2006, semiconductor layers act as an active medium. These layers consist alternately of aluminum arsenide (AlAs) and gallium arsenide (GaAs) and the incident sound wave excites the electrons inside. The resulting lattice vibrations, called phonons , are ultimately responsible for amplifying the sound wave. Under suitable conditions, these phonons oscillate in phase with the incident sound wave and lead to an increase in amplitude. Since the oscillation frequency of these phonons is not arbitrary, but depends on the material, only certain frequencies are amplified. Therefore, the exiting sound wave is not only amplified, but also coherent.

So far, however, the separation of the phonon frequencies has not yet succeeded so that the emerging sound wave is a mixture of different frequencies. It is not expected to be ready for the market in the near future.

Web links

Individual evidence

  1. ↑ IV Volkov, ST Zavtrak, IS Kuten: Theory of sound amplification by stimulated emission of radiation with consideration for coagulation . In: Phys. Rev. E . tape 56 , 1997, pp. 1097 , doi : 10.1103 / PhysRevE.56.1097 ( aps.org ).
  2. ↑ AJ Kent et al .: Acoustic Phonon Emission from a Weakly Coupled Superlattice under Vertical Electron Transport: Observation of Phonon Resonance . In: Phys. Rev. Lett. tape 96 , 2006, p. 215504 , doi : 10.1103 / PhysRevLett.96.215504 (English, aps.org ).