Observation of the Dissipative Parametric Gain in a GaAs/AlGaAs Superlattice

TL;DR

This paper reports the first experimental observation of dissipative parametric gain in a GaAs/AlGaAs superlattice, demonstrating a new mechanism for generating high-frequency oscillations at room temperature.

Contribution

It provides the first experimental evidence of dissipative parametric generation in superlattices, highlighting a new mechanism involving negative differential velocity variations.

Findings

Observation of dissipative parametric gain in superlattices

Identification of a mechanism involving negative differential velocity

Potential for room-temperature GHz-THz frequency generation

Abstract

Parametric generation of oscillations and waves is a paradigm, which is known to be realized in various physical systems. Unique properties of quantum superlattices allow to investigate high-frequency phenomena induced by the Bragg reflections and negative differential velocity of the miniband electrons. Effects of parametric gain in the superlattices at different strengths of dissipation have been earlier discussed in a number of theoretical works, but their experimental demonstrations are so far absent. Here, we report on the first observation of the dissipative parametric generation in a subcritically doped GaAs/AlGaAs superlattice subjected to a dc bias and a microwave pump. We argue that the dissipative parametric mechanism originates from a periodic variation of the negative differential velocity. It enforces excitation of slow electrostatic waves in the superlattice which provide a significant enhancement of the gain coefficient. This work paves the way for a development of a miniature solid-state parametric generator of GHz\nobreakdash--THz frequencies operating at room temperature.