Terahertz Bloch oscillator with a modulated bias

TL;DR

This paper demonstrates the theoretical possibility of a stable terahertz Bloch oscillator in superlattices by using quasistatic bias modulation with multi-harmonic waveforms, overcoming previous stability issues.

Contribution

It introduces a novel approach of bias modulation with multiple harmonics to achieve stable THz gain in superlattice devices, addressing longstanding instability problems.

Findings

Stable THz gain is theoretically feasible with quasistatic bias modulation.

Multiharmonic waveforms are necessary for the modulation.

Overcomes the instability of homogeneous electric fields in Bloch oscillators.

Abstract

Electrons performing Bloch oscillations in an energy band of a dc-biased superlattice in the presence of weak dissipation can potentially generate THz fields at room temperature. The realization of such Bloch oscillator is a long-standing problem due to the instability of a homogeneous electric field in conditions of negative differential conductivity. We establish the theoretical feasibility of stable THz gain in a long superlattice device in which the bias is quasistatically modulated by microwave fields. The modulation waveforms must have at least two harmonics in their spectra.