Mechanism of THz emission from asymmetric double quantum wells

Terahertz electromagnetically induced optical limiter in asymmetric coupled quantum wells

This paper explores the optical limiting (OL) characteristics of an input probe field within a closed-loop asymmetric coupled quantum well (ACQW) system. Our research reveals that the application of Terahertz (THz) coupling laser fields can induce the OL behavior within the THz domain in the ACQW. The study demonstrates that revers saturable absorption arises through cross-Kerr nonlinearity, contributing to the emergence of OL behavior. Additionally, it is shown that the self-defocusing is induced concurrently within the system, further enhancing nonlinear refractive OL effects. Furthermore, it is revealed that the properties of induced OL can be manipulated by adjusting the characteristics of the applied fields. The discovered outcomes hold potential utility in safeguarding sensors and detectors operating within the THz band.

Coherent terahertz control of vertical transport in semiconductor heterostructures

Coherent-control protocols are introduced to selectively transport electrons, excitons, or pure two-particle correlations through semiconductor interfaces. The scheme is tested in a double-quantum-well structure where a sequence of terahertz pulses is applied to induce the vertical excitation transfer between the wells. Using a microscopic theory, it is shown that efficient and highly selective transfer can be realized even in the presence of the unavoidable scattering and dephasing processes.

Coherent Hall effect in a semiconductor superlattice

The coherent Hall effect denotes the transient Hall response of impulsively excited coherent charge-carrier wave packets in a solid. We report the first experimental study of this phenomenon (i) using a semiconductor superlattice in crossed electric and magnetic fields as a model for three-dimensional materials and (ii) employing a contactless optoelectronic technique to probe the transient currents. Two field regimes with distinctly different oscillatory wave packet dynamics are found, separated from each other by a transition region where all oscillations are suppressed.