Transient stimulated emission from multi-split-gated graphene structure

TL;DR

This paper proposes a mechanism for transient stimulated emission in multi-split-gated graphene structures, demonstrating potential for mid-infrared lasing with specific conditions and analyzing effects like waveguide losses and temperature.

Contribution

It introduces a new mechanism for transient population inversion in graphene with multi-split gates and analyzes conditions for lasing in the mid-IR spectral region.

Findings

Stimulated emission occurs after lateral carrier spreading due to drift-diffusion.

Lasing conditions with gain above 100 cm$^{-1}$ are achievable in specific graphene structures.

Waveguide losses and temperature effects influence the lasing performance.

Abstract

Mechanism of transient population inversion in graphene with multi-splitted (interdigitated) top-gate and grounded back gate is suggested and examined for the mid-infrared (mid-IR) spectral region. Efficient stimulated emission after fast lateral spreading of carriers due to drift-diffusion processes is found for the case of a slow electron-hole recombination in the passive region. We show that with the large gate-to-graphene distance the drift process always precedes the diffusion process, due to the ineffective screening of the inplane electric field by the gates. Conditions for lasing with a gain above 100 cm$^{-1}$ are found for cases of single- and multi-layer graphene placed in the waveguide formed by the top and back gates. Both the waveguide losses and temperature effects are analyzed.