Platinum diselenide (PtSe2), classified as a noble metal dichalcogenide, has garnered substantial interest owing to its layer-dependent band structure, remarkable air-stability, and high charge-carrier mobilities. These properties make it highly promising for a wide array of applications in next-generation electronic and optoelectronic devices, as well as sensors. Additionally, two-dimensional (2D) PtSe2 demonstrates significant potential as a saturable absorber due to its exceptional nonlinear optical response across an ultrabroad spectra range, presenting exciting opportunities in ultrafast and nonlinear photonics. In this work, we explore the second-order nonlinear optical characteristics of 2D PtSe2 by analyzing its second-harmonic generation (SHG) excited by a pulsed laser at 1064 nm. Our investigation unveils a layer-dependent SHG response in PtSe2, with prominent SHG intensity observed in few-layer PtSe2. The distinct six-fold polarization dependence pattern observed in the SHG intensity reflects the inherent threefold rotational symmetry inherent to the PtSe2 crystal structure. Remarkably, the SHG intensity of 4-layer PtSe2 surpasses that of mechanically exfoliated monolayer molybdenum disulfide (MoS2) by approximately two orders of magnitude (60-fold), underscoring its exceptional second-order nonlinear optical response. Combined with its ultrahigh air-stability, these distinctive nonlinear optical characteristics position two-dimensional PtSe2 as a promising candidate for ultrathin nonlinear nanophotonic devices.

中文翻译：

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二维 PtSe2 中的强二次谐波产生


二硒化铂 （PtSe2） 被归类为贵金属二硫化物，由于其层依赖性能带结构、卓越的空气稳定性和高载流子迁移率而引起了人们的极大兴趣。这些特性使其在下一代电子和光电器件以及传感器中的广泛应用前景广阔。此外，二维 （2D） PtSe2 在超宽光谱范围内具有出色的非线性光学响应，因此显示出作为可饱和吸收器的巨大潜力，为超快和非线性光子学提供了令人兴奋的机会。在这项工作中，我们通过分析由 1064 nm 脉冲激光激发的二次谐波产生 （SHG） 来探索 2D PtSe2 的二阶非线性光学特性。我们的研究揭示了 PtSe2 中的层依赖性 SHG 响应，在少数层 PtSe2 中观察到明显的 SHG 强度。在 SHG 强度中观察到的明显的六重偏振依赖性模式反映了 PtSe2 晶体结构固有的固有的三重旋转对称性。值得注意的是，4 层 PtSe2 的 SHG 强度比机械剥离的单层二硫化钼 （MoS2） 高出大约两个数量级（60 倍），突显了其卓越的二阶非线性光学响应。结合其超高的空气稳定性，这些独特的非线性光学特性使二维 PtSe2 成为超薄非线性纳米光子器件的有前途的候选者。