Institute of Electrical and Electronics Engineers Inc.;IEEE
摘要:
摘要： The optical nonlinear absorption (NLA) property of multilayer graphene was investigated by Z-scan technique with picosecond laser pulse of 532-nm wavelength. Graphene samples were fabricated by chemical vapor deposition (CVD) with different number of layers, which were 1-, 8-, and 16-layer. The dependence of NLA coefficient α(I) on number of layers was investigated under the laser intensity of 7-80 GW/cm 2 . The results showed that α(I) increased as the number of layer increased, and decreased as the laser intensity increased. Nonlinearities of graphene were mainly caused by saturable absorption (SA) effect. The 1-, 8-, and 16-layer graphene exhibited SA nonlinearity. However, reversed SA (RSA) nonlinearity was observed for 16-layer graphene only. The RSA was resulted from two-photon absorption due to layer stacking-induced bandgap opening, confirmed by the α(I) measurement. The RSA may reduce the stability of mode-locking and therefore, it suggests that the lower layer stacking in CVD fabricated graphene is preferable to use as saturable absorbers in laser mode-locking. 其他題名： LPT 出版者： IEEE 出版日期： 2015-09-01 出處： IEEE photonics technology letters, 2015-09, Vol.27 (17), p.1791-1794 資源來源： IEEE Electronic Library (IEL) 識別號： ISSN: 1041-1135 識別號： EISSN: 1941-0174 識別號： DOI: 10.1109/LPT.2015.2438230 識別號： CODEN: IPTLEL
