Terahertz Bloch oscillator with a modulated bias

Phys Rev Lett. 2009 Apr 10;102(14):140405. doi: 10.1103/PhysRevLett.102.140405. Epub 2009 Apr 10.

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 a 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.