Bohn Justus, Luk Ting Shan, Tollerton Craig, Hutchings Sam W, Brener Igal, Horsley Simon, Barnes William L, Hendry Euan
School of Physics, University of Exeter, Exeter, UK.
Sandia National Laboratories, Albuquerque, NM, USA.
Nat Commun. 2021 Feb 15;12(1):1017. doi: 10.1038/s41467-021-21332-y.
Nonlinear optical devices and their implementation into modern nanophotonic architectures are constrained by their usually moderate nonlinear response. Recently, epsilon-near-zero (ENZ) materials have been found to have a strong optical nonlinearity, which can be enhanced through the use of cavities or nano-structuring. Here, we study the pump dependent properties of the plasmon resonance in the ENZ region in a thin layer of indium tin oxide (ITO). Exciting this mode using the Kretschmann-Raether configuration, we study reflection switching properties of a 60 nm layer close to the resonant plasmon frequency. We demonstrate a thermal switching mechanism, which results in a shift in the plasmon resonance frequency of 20 THz for a TM pump intensity of 70 GW cm. For degenerate pump and probe frequencies, we highlight an additional two-beam coupling contribution, not previously isolated in ENZ nonlinear optics studies, which leads to an overall pump induced change in reflection from 1% to 45%.
非线性光学器件及其在现代纳米光子结构中的应用受到其通常适度的非线性响应的限制。最近，发现近零介电常数（ENZ）材料具有很强的光学非线性，可通过使用腔或纳米结构来增强。在此，我们研究了氧化铟锡（ITO）薄层中ENZ区域等离激元共振的泵浦依赖特性。使用Kretschmann-Raether配置激发此模式，我们研究了接近共振等离激元频率的60nm层的反射切换特性。我们展示了一种热切换机制，对于70 GW/cm的TM泵浦强度，该机制会导致等离激元共振频率偏移20 THz。对于简并泵浦和探测频率，我们突出了一种额外的双光束耦合贡献，这在以前的ENZ非线性光学研究中未被分离出来，它导致泵浦引起的反射总体变化从1%到45%。
