High-frequency absorption and gain in superlattices: Semiquasistatic approach

TL;DR

This paper introduces a semiquasistatic approach to analyze THz radiation generation and amplification in semiconductor superlattices, providing formulas and geometric insights for optimizing gain in nonlinear electric regimes.

Contribution

It develops a novel semiquasistatic theoretical framework with difference formulas and geometric interpretation for THz gain in superlattices, advancing nonlinear THz source and detector design.

Findings

Derived difference formulas for THz absorption and gain.

Provided geometric interpretation for optimizing gain.

Contributed to development of THz sources and detectors.

Abstract

We consider a generation and an amplification of THz radiation in semiconductor superlattices under the action of microwave pump field. Electrons belonging to a single miniband of the superlattice interact quasistatically with the pump field and dynamically with a signal THz field. Within this semiquasistic approach we derive elegant difference formulas describing absorption (gain) of the weak THz signal. We present an instructive geometric interpretation of the absorption formulas which allows a search of optimum conditions for the gain employing only a simple qualitative analysis. Our theoretical findings contribute to the development of sources and detectors of THz radiation that are using nonlinear electric properties of semiconductor superlattices.