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.
@article{arxiv.1307.3792,
title = {Transient stimulated emission from multi-split-gated graphene structure},
author = {A. Satou and F. T. Vasko and T. Otsuji and V. V. Mitin},
journal= {arXiv preprint arXiv:1307.3792},
year = {2015}
}