Cheng Xin, Dong Ningning, Li Bin, Zhang Xiaoyan, Zhang Saifeng, Jiao Jia, Blau Werner J, Zhang Long, Wang Jun
Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
Opt Express. 2013 Jul 15;21(14):16486-93. doi: 10.1364/OE.21.016486.
Nonlinear scattering, originating from laser induced solvent micro-bubbles and/or micro-plasmas, is regarded as the principal mechanism for nonlinear optical (NLO) response of graphene dispersions at ns timescale. In this work, we report the significant enhancement of NLO response of graphene dispersions by decreasing the atmospheric pressure, which has strong influence on the formation and growth of micro-bubbles and/or micro-plasmas. A modified open-aperture Z-scan apparatus in combination with a vacuum system was used to study the effect of vacuum pressure on the NLO property of graphene dispersions prepared by liquid-phase exfoliation technique. We show that the atmospheric pressure can be utilized to control and tune the nonlinear responses of the graphene dispersions for ns laser pulses at both 532 nm and 1064 nm. The lower the vacuum pressure was, the larger the NLO response was. In contrast, the NLO property of fullerene was found to be independent of the pressure change, due to its nature of nonlinear absorption. This work affords a simple method to distinguish the nonlinear scattering and absorption mechanisms for NLO nanomaterials.
源自激光诱导的溶剂微泡和/或微等离子体的非线性散射，被视为纳秒时间尺度下石墨烯分散体非线性光学（NLO）响应的主要机制。在这项工作中，我们报道了通过降低大气压来显著增强石墨烯分散体的NLO响应，大气压对微泡和/或微等离子体的形成和生长有强烈影响。使用结合了真空系统的改进型开孔Z扫描装置，研究真空压力对通过液相剥离技术制备的石墨烯分散体的NLO性质的影响。我们表明，大气压可用于控制和调节532 nm和1064 nm纳秒激光脉冲下石墨烯分散体的非线性响应。真空压力越低，NLO响应越大。相比之下，由于富勒烯的非线性吸收性质，发现其NLO性质与压力变化无关。这项工作提供了一种简单的方法来区分NLO纳米材料的非线性散射和吸收机制。
