Optimal Absorption of Acoustic Waves by a Boundary

Nonlinear absorption of surface acoustic waves by composite fermions

– Absorption of surface acoustic waves by a two-dimensional electron gas in a perpendicular magnetic field is considered. The structure of such system at the filling factor ν close to 1/2 can be understood as a gas of composite fermions. It is shown that the absorption at ν = 1/2 can be strongly nonlinear, while small deviation form 1/2 will restore the linear absorption. The study of nonlinear...

Detection of Acoustic Zone-boundary Phonons by Phonon Difference Absorption

A new method for detection of zone-boundary phonons is reported. Phonons are detected by phonon difference absorption of far-infrared laser radiation. We present experimental results obtained for TlCl and TlBr crystals. Phonons are generated by nonradiative transitions in optically excited crystals. Our experiments indicate long-lived zone-boundary phonons at low crystal temperature and a stron...

Determination of sediments diameter using acoustic waves

The use of acoustic waves in researches related to sea water is of most importance among scientists recently. Since these waves are the only waves, transmitted in water with lowest attenuation and high speed, they can be used in many scientific fields. The main goal of this research is to better understand the physics and mechanisms of sound-seabed interaction, including acoustic penetration, p...

Super-Absorption of Acoustic Waves with Bubble Meta-Screens

IIlISSION, ABSORPTION AND PROPAGATION OF ACOUSTIC TU.·WAVES IN SOLIDS

Recent experimental develop menta in generation and detection of THz acoustical phonon. have led to studies of phonon emission, propagation and absorption in solidi. New resulta of this acoustical phonon spectroscopy concern phonon interaction. with collective excitations (phonons, photons, magnons), localized exoitations (resonant scattering of impurities, radiationleas transi. tions) and elec...