Ultra-compact injection terahertz laser using the resonant inter-layer radiative transitions in multi-graphene-layer structure

TL;DR

This paper presents an optimized design for a ultra-compact, room-temperature, voltage-tunable terahertz laser based on resonant radiative transitions in multi-graphene-layer structures, achieving high gain and minimal size.

Contribution

It introduces an optimized surface plasmonic waveguide geometry for graphene-based terahertz lasers, enhancing gain and reducing threshold length.

Findings

Maximum modal gain of ~500 cm-1 at 8 THz

Threshold length as small as 50 micrometers

Optimal number of graphene layer pairs for maximum gain

Abstract

The optimization of laser resonators represents a crucial issue for the design of terahertz semiconductor lasers with high gain and low absorption loss. In this paper, we put forward and optimize the surface plasmonic metal waveguide geometry for the recently proposed terahertz injection laser based on resonant radiative transitions between tunnel-coupled grapheme layers. We find an optimal number of active graphene layer pairs corresponding to the maximum net modal gain. The maximum gain increases with frequency and can be as large as ~ 500 cm-1 at 8 THz, while the threshold length of laser resonator can be as small as ~ 50 mkm. Our findings substantiate the possibility of ultra-compact voltage-tunable graphene-based lasers operating at room temperature.