Ultrafast Saturable Absorption of Two-Dimensional MoS2 Nanosheets
Ultrafast Saturable Absorption of Two-Dimensional MoS2 Nanosheets
复制标题
二维MoS2纳米片的超快饱和吸收
DOI：
10.1021/nn403886t
复制
发表时间：
2013-10-01
期刊：
影响因子：
17.1
通讯作者：
Blau, Werner Josef
中科院分区：
文献类型：
--
作者：
Wang, Kangpeng;Wang, Jun;Blau, Werner Josef
采用高产量生产的层状材料的液相剥离，二硫化钼（MoS 2）的分散体与大人口的单层和少数层制备。电子显微镜验证了二维二硫化钼纳米结构的高质量。原子力显微镜分析显示，类似于39%的MoS 2薄片具有小于5 nm的厚度。E-2g（1）和A（1g）拉曼模式的线宽和频率差证实了从块状二硫化钼到分散体的薄片厚度的有效减小。利用开孔Z扫描技术研究了超快非线性光学（NLO）特性。所有实验都是使用来自锁模钛宝石激光器的800 nm处的100 fs脉冲进行的。MoS 2纳米片对飞秒脉冲表现出显著的可饱和吸收（SA），导致三阶非线性光学（NLO）极化率Imchi（3）类似于10（-15）esu，品质因数类似于10（-15）esu cm，自由载流子吸收截面类似于10（-17）cm（2）。感应自由载流子密度和弛豫时间估计分别为10（16）cm（-3）和30 fs。在相同的激发条件下，二硫化钼分散体比石墨烯分散体显示出更好的SA响应。
Employing high-yield production of layered materials by liquid-phase exfoliation, molybdenum disulfide (MoS2) dispersions with large populations of single and few layers were prepared. Electron microscopy verified the high quality of the two-dimensional MoS2 nanostructures. Atomic force microscopy analysis revealed that similar to 39% of the MoS2 flakes had thicknesses of less than 5 nm. Linewidth and frequency difference of the E-2g(1) and A(1g) Raman modes confirmed the effective reduction of flake thicknesses from the bulk MoS2 to the dispersions. Ultrafast nonlinear optical (NLO) properties were investigated using an open-aperture Z-scan technique. All experiments were performed using 100 fs pulses at 800 nm from a mode-locked Ti:sapphire laser. The MoS2 nanosheets exhibited significant saturable absorption (SA) for the femtosecond pulses, resulting in the third-order NLO susceptibility Im chi((3)) similar to 10(-15) esu, figure of merit similar to 10(-15) esu cm, and free-carrier absorption cross section similar to 10(-17) cm(2). Induced free carrier density and the relaxation time were estimated to be similar to 10(16) cm(-3) and similar to 30 fs, respectively. At the same excitation condition, the MoS2 dispersions show better SA response than the graphene dispersions.