Open AccessSaturable absorption behavior of free-standing graphene polymer composite films over broad wavelength and time ranges
Author(s) -
YiSi Feng,
Ningning Dong,
Gaozhong Wang,
Yuanxin Li,
Saifeng Zhang,
Kangpeng Wang,
Long Zhang,
Werner J. Blau,
Jun Wang
Publication year - 2015
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.23.000559
Subject(s) - materials science , saturable absorption , optics , graphene , laser , absorption (acoustics) , exfoliation joint , wavelength , figure of merit , polyvinyl alcohol , fiber laser , optoelectronics , nanotechnology , composite material , physics
A comparative research on saturable absorption (SA) behavior dependence on wavelength and pulse duration was performed for graphene polymer composites. Free-standing graphene-polyvinyl alcohol (PVA) composite films were fabricated by using solution cast method in combination of liquid phase exfoliation. SA responses were observed by using an open-aperture Z-scan technique for 340 fs pulses at 1030 nm and 515 nm from a mode-locked fiber laser, and 6 ns pulses at 1064 nm and 532 nm from a Q-switched Nd:YAG laser. The graphene films possess better SA property, i.e., larger SA coefficient and figure of merit (FOM), and lower saturation intensity I(s), for ns pulses than that for fs pulses at the similar near infrared (NIR) wavelength. For fs pulses, the films show better SA response at 1030 nm than that at 515 nm. By employing slow and fast SA modelling, the excited state and ground state absorption cross sections were estimated to be ~10(-17) cm(2), and the ratio was ~0.6 at NIR for both fs and ns pulses.