Acoustic Self-induced Transparency Research Articles

Vector soliton of self-induced transparency of a generalized love wave

A theory of acoustic self-induced transparency of a two-component vector soliton for a generalized Love wave is constructed. The three-layer system contains a resonance transition layer with paramagnetic impurity atoms or quantum dots. It is shown that, under these conditions, a vector soliton of the generalized Love wave can be formed. It oscillates at the sum and difference frequencies in the vicinity of the carrier wave frequency. Explicit analytical expressions for the parameters of a nonlinear surface acoustic wave are presented. The parameters depend on the elastic properties of the contacting media, the resonance transition layer, and the transverse structure of the wave. Numerical calculations are carried out for the three-layer Al2O3/ZnO/SiO2 system. The significant difference between the two-component vector soliton and singlecomponent soliton is shown.

Acoustic self-induced transparency for transverse waves in a system with resonant and quasi-resonant transitions

A theoretical analysis of acoustic self-induced transparency is presented for transverse elastic waves propagating perpendicular to an applied magnetic field through a crystal with spin-3/2 paramagnetic impurities. The interaction between an acoustic pulse and magnetic field is described by Maxwell-Bloch-type equations for a system with transitions inhomogeneously broadened because of a quadrupole Stark shift. If the pulse carrier frequency is resonant with one transition and quasi-resonant with another transition, then the evolution of a one-dimensional pulse is described by an integrable Konno-Kameyama-Sanuki (KKS) equation. The underlying physics of its soliton solution and the corresponding behavior of the medium are analyzed. Self-focusing and self-trapping conditions are found for a pulse of finite transverse size. In the latter regime, the pulse stretches along the propagation direction, transforming into a “hollow bullet,” while its transverse size remains constant.

Modes of nonlinear acoustic transparency in the strained paramagnetic crystal

The propagation of transverse-longitudinal acoustic pulses through a strained cubic crystal containing resonant paramagnetic impurities with effective spin S =1 is investigated. It is supposed that the pulses propagate under arbitrary angle with respect to the direction of the external static deformation parallel to the fourth-order symmetry axis. In this geometry, both the transverse and longitudinal components of the acoustic field have high-frequency and zero-frequency spectral components. We show that a pulse can propagate in modes different from the acoustic self-induced transparency. In particular, a pulse propagating in the mode of an acoustic self-induced supertransparency substantially changes the populations of the spin sublevels, but its group velocity remains almost equal to the linear velocity of the sound. If a pulse propagates in the acoustic extraordinary transparency mode, then its group velocity is substantially lower while the sublevel populations remain virtually invariant. Also, the modes of propagation under conditions of weakly excited spin transitions and large detuning of the pulse high-frequency components are identified.

Acoustic-transparency effects for longitudinal-transverse waves

The propagation of longitudinal-transverse acoustic pulses in a system of resonance paramagnetic impurities is theoretically investigated. It is shown that, when the transverse component of a pulse is dominant and propagates along an external magnetic field, a regime of acoustic self-induced transparency is implemented. In the opposite limit, a new soliton regime is implemented, accompanied by a decrease of the propagation rate similar to what takes place for self-induced transparency. In this case, however, the populations of the quantum Zeeman sublevels remain virtually unchanged, and the transverse component of the pulse experiences phase modulation. A close parallel is drawn with the corresponding optical effects of laser-pulse propagation. © 2004 Optical Society of America

Influence of relaxation on the profile of a nonlinear acoustic pulse

The influence of transverse relaxation on a nonlinear acoustic wave generated in the presence of the acoustic self-induced transparency (SIT) phenomenon is investigated. An explicit analytical equation for the profile of the nonlinear acoustic wave is derived by a perturbation theory developed on the basis of the inverse scattering problem. This equation provides a possible means for investigating experimentally the profile of an acoustic SIT pulse with allowance for relaxation effects, so that these results can be used to construct new types of acoustoelectronic devices.

Influence of relaxation on the acoustic self-induced transparency

Using a singular perturbation theory for the method of the inverse scattering transform, the influence of transverse relaxation on the acoustic self-induced transparency is considered. It is shown that account of the relaxation improves the quantitative agreement of the theory with experiment.

Acoustic self-induced transparency in three-level spin systems

Acoustic self-induced transparency in three-level spin systems

On the theory of acoustic self-induced transparency

The effect of coherent interaction of a sound pulse of longitudinal polarization with an electron-nuclear spin system in an external constant magnetic field under the conditions of a “forbidden” transition is investigated. The parameters of the stationary electron-nuclear sound pulse are determined.

The theory of acoustic self-induced transparency in magneto-ordered mediums

Possible acoustic self-induced transparency of magneto-ordered medium is under investigation in the paper. Heisenberg model of a ferromagnet and antiferromagnet in magnetic field is considered as an example. The allowance made for exchange interaction between electron spins is shown to result in qualitative change of self-induced transparency picture; in particular, the dispersion low for the carrier sound wave varies along with the character of phase modulation and the shape of the stationary pulse. The possibility of experimental observation of the above-mentioned phenomenon is discussed.