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Optimizing Nonlinear Optical Visibility of Two-Dimensional Materials
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2017-09-25 00:00:00 , DOI: 10.1021/acsami.7b09807
Xianchong Miao 1 , Ningning Xuan , Qi Liu 1 , Weishu Wu 1 , Hanqi Liu , Zhengzong Sun , Minbiao Ji 1
Affiliation  

Two-dimensional (2D) materials have attracted broad research interests across various nonlinear optical (NLO) studies, including nonlinear photoluminescence (NPL), second harmonic generation (SHG), transient absorption (TA), and so forth. These studies have unveiled important features and information of 2D materials, such as in grain boundaries, defects, and crystal orientations. However, as most research studies focused on the intrinsic NLO processes, little attention has been paid to the substrates underneath. Here, we discovered that the NLO signal depends significantly on the thickness of SiO2 in SiO2/Si substrates. A 40-fold enhancement of the NPL signal of graphene was observed when the SiO2 thickness was varied from 270 to 125 nm under 800 nm excitation. We systematically studied the NPL intensity of graphene on three different SiO2 thicknesses within a pump wavelength range of 800–1100 nm. The results agreed with a numerical model based on back reflection and interference. Furthermore, we have extended our measurements to include TA and SHG of graphene and MoS2, confirming that SiO2 thickness has similar effects on all of the three major types of NLO signals. Our results will serve as an important guidance for choosing the optimum substrates to conduct NLO research studies on 2D materials.

中文翻译:

优化二维材料的非线性光学可见性

二维(2D)材料在各种非线性光学(NLO)研究中引起了广泛的研究兴趣,包括非线性光致发光(NPL),二次谐波产生(SHG),瞬态吸收(TA)等。这些研究揭示了二维材料的重要特征和信息,例如晶界,缺陷和晶体取向。但是,由于大多数研究都集中在固有的NLO工艺上,因此很少关注下面的基材。在这里,我们发现,NLO信号在SiO的厚度显著取决于2中的SiO 2 / Si衬底上。当SiO 2时,石墨烯的NPL信号增强了40倍在800 nm激发下,其厚度从270到125 nm不等。我们系统地研究了在800-1100 nm泵浦波长范围内三种不同SiO 2厚度下石墨烯的NPL强度。结果与基于背反射和干涉的数值模型一致。此外,我们将测量范围扩展到包括石墨烯和MoS 2的TA和SHG ,证实了SiO 2厚度对NLO信号的三种主要类型均具有相似的影响。我们的结果将为选择最佳基材进行2D材料的NLO研究提供重要指导。
更新日期:2017-09-26
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