Open AccessSaturable absorption of femtosecond optical pulses in multilayer turbostratic graphene
Author(s) -
Fanqi Meng,
Mark D. Thomson,
Federica Bianco,
Antonio Rossi,
Domenica Convertino,
Alessandro Tredicucci,
Hartmut G. Roskos
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.015261
Subject(s) - materials science , saturable absorption , femtosecond , optics , laser , graphene , transmittance , ultrashort pulse , scattering , fluence , optoelectronics , wavelength , fiber laser , physics , nanotechnology
We investigate the nonlinear transmission of a ~280-layer turbostratic graphene sheet for near-infrared amplifier laser pulses (775 nm, Ti:sapphire laser) with a duration of 150-fs and 20-fs. Saturable absorption is observed in both cases, however it is not very strong, amounting to ~13% transmittance change for the 20-fs (150-fs) pulses at a peak intensity of 30 GW/cm 2 (4 GW/cm 2 ). The dependence on incident peak intensity is reproduced well using a theoretical model for the time-dependent saturable absorption, where the excited carriers vacate the photo-excited energy range within 3-5 fs, which we attribute to energy redistribution due to carrier-carrier scattering. This is also supported by spectrally resolved measurements for the 20-fs pulses, which show a marked dependence of the degree of saturation on the photon energy. A key result is that the shorter pulses do not yield a lower saturation fluence, due to the combined effects of the broader excitation bandwidth, and the rapid and broad energy redistribution. We also predict the potential performance of multilayer graphene samples for removing pedestal and pre-pulse structure from ultrafast high-energy pulses.