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Proceedings Paper

Effect of high-optical excitation on the ultrafast electron dynamics in stacked-monolayer graphene samples
Author(s): Juan A. Castañeda; Henrique Guimarães Rosa; José C. V. Gomes; Eunezio A. Thoroh de Souza; Carlos H. de Brito-Cruz; Hugo L. Fragnito; Lázaro A. Padilha
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Paper Abstract

We report on transient absorption experiments performed at high optical excitation fluences and used to study the ultrafast dynamics in graphene. We employed a degenerated scheme of pump and probe at 800 nm (1.55 eV). The time resolution of our measurements was limited by the pulse duration ~ 100 fs. The samples were prepared by chemical vapor deposition (CVD) as single-layers on silica and, then staked layer-by-layer in order to make a stack of up to 5 graphene monolayers. We observed saturable absorption (SA) and fluence-dependent relaxation times. We see that the ultrafast carrier dynamics is composed by two decay mechanisms, one with response time of about 200 fs and a slower process of about 1 ps. The fast decay, due to both carrier-carrier and carrier-optical phonon scattering, becomes slower when the density of excited carrier was increased. We implemented a theoretical model and found that both the optical phonon rate emission and the optical phonon lifetime are affect by the pump fluence.

Paper Details

Date Published: 13 May 2016
PDF: 8 pages
Proc. SPIE 9835, Ultrafast Bandgap Photonics, 983517 (13 May 2016); doi: 10.1117/12.2235501
Show Author Affiliations
Juan A. Castañeda, Univ. Estadual de Campinas (Brazil)
Henrique Guimarães Rosa, National Univ. of Singapore (Brazil)
José C. V. Gomes, Univ. Estadual de Campinas (Singapore)
Eunezio A. Thoroh de Souza, Univ. Presbiteriana Mackenzie (Brazil)
Carlos H. de Brito-Cruz, Univ. Estadual de Campinas (Brazil)
Hugo L. Fragnito, Univ. Estadual de Campinas (Brazil)
Univ. Presbiteriana Mackenzie (Brazil)
Lázaro A. Padilha, Univ. Estadual de Campinas (Brazil)

Published in SPIE Proceedings Vol. 9835:
Ultrafast Bandgap Photonics
Michael K. Rafailov; Eric Mazur, Editor(s)

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