Abstract-Pulse shaping in the terahertz frequency range for the control of photo-excited carriers in graphene

Denis Gagnon, Joey Dumont, François Fillion-Gourdeau,Steve MacLean,

https://www.osapublishing.org/josab/abstract.cfm?uri=josab-35-12-3021

The shape of a few-cycle terahertz (THz) laser pulse can be optimized to provide control over conduction band populations in graphene. To demonstrate this control in a theoretical way, a spectral parametrization of the driving pulse using 𝐵$B$-splines is used in order to obtain experimentally realistic pulses of bandwidth ∼30  THz$\sim 30\mathrm{THz}$. Optimization of the spectral shape is performed via differential evolution, using the 𝐵$B$-splines expansion coefficients as decision variables. Numerical results show the possibility of changing the carrier density in graphene by a factor of 4 for a fixed pulse energy. In addition, we show that it is possible to selectively suppress or enhance multiphoton absorption features by optimizing over narrow windows in reciprocal space. The application of pulse shaping to the control of scattering mechanisms in graphene is also discussed.

© 2018 Optical Society of America

Abstract-Optimization of carrier density in graphene via terahertz pulse shaping

Denis Gagnon, Joey Dumont, François Fillion-Gourdeau, Steve MacLean

(Submitted on 26 Oct 2017)

https://arxiv.org/abs/1710.09889

Pulse shaping calculations for the control of photo-excited carrier densities in graphene are presented. A spectral parametrization of the incident pulse using B-splines is used in order to obtain experimentally realistic pulses of bandwidth ∼ 3 THz. Optimization of the spectral shape is performed numerically via differential evolution, using the B-splines expansion coefficients as decision variables. Using this high-level optimization procedure, we find that it is possible to change the carrier density in graphene by a factor of 4 for a fixed pulse energy. The selective suppression of multi-photon absorption features in reciprocal space is also discussed, as well as the application of this theoretical work to the control of scattering mechanisms in graphene.