Verma Akansha, Soni Ashish, Sarkar Abdus Salam, Pal Suman Kalyan
Opt Lett. 2023 Sep 1;48(17):4641-4644. doi: 10.1364/OL.498545.
Tin (II) monosulfide (SnS) has attracted considerable attention in emerging photonics and optoelectronics because of high carrier mobility, large absorption coefficient, anisotropic linear and nonlinear optical properties, and long-time stability. In this Letter, we report third-order nonlinear absorption and refraction of SnS quantum dots (QDs). Under excitation with 800-nm femtosecond pulses, QDs exhibit saturable absorption (saturation intensity ∼ 47.69 GW/cm) and positive refractive nonlinearity (nonlinear refraction coefficient ∼ 1.24 × 10 cm/W). Nonetheless, we investigate charge carrier dynamics using femtosecond transient absorption spectroscopy and propose the presence of midgap defect states which not only dictate carrier dynamics but also give rise to nonlinear optical properties in SnS QDs.
硫化亚锡（SnS）因其高载流子迁移率、大吸收系数、各向异性的线性和非线性光学特性以及长期稳定性，在新兴光子学和光电子学领域引起了广泛关注。在本信函中，我们报告了硫化亚锡量子点（QDs）的三阶非线性吸收和折射。在800纳米飞秒脉冲激发下，量子点表现出饱和吸收（饱和强度约为47.69 GW/cm）和正折射非线性（非线性折射系数约为1.24×10 cm/W）。尽管如此，我们使用飞秒瞬态吸收光谱研究了电荷载流子动力学，并提出禁带中缺陷态的存在，这些缺陷态不仅决定了载流子动力学，还导致了硫化亚锡量子点中的非线性光学特性。
