Eur. Phys. J. D 59, 233-240 (2010)
https://doi.org/10.1140/epjd/e2010-00158-8

Solid-state traveling-wave amplifiers and oscillators in the THz range: effect of electron collisions

¹ Department of Electrical and Electronic Engineering, Optical and Semiconductor Devices Group, Imperial College, London Exhibition Road, London, SW7 2AZ, UK
² Erlangen Graduate School in Advanced Optical Technologies, University of Erlangen-Nuremberg, Paul-Gordan-Str. 6 91052, Erlangen, Germany

Corresponding author: ^a osydoruk@imperial.ac.uk

Received: 12 April 2010
Published online: 11 June 2010

Abstract

Due to their high plasma frequencies, drifting semiconductor plasmas interacting with slow electromagnetic waves hold promise for terahertz amplifiers and oscillators. In these devices, the gain and the type of instabilities are influenced by electron collisions. To study the effect of collisions, we developed a two-wave model describing the interaction between drifting solid-state plasmas and electromagnetic waves. This paper analyzes the two-wave dispersion relation for representative examples. As the examples show, convective and absolute instabilities can occur at high and low collision frequencies depending on the relationship between the collision frequency and the coupling coefficient. Surprisingly, an absolute instability occurs when collision-dominated plasmas interact with backward waves. The model can be used to determine the potential of a particular configuration in a solid-state amplifier or oscillator.