Broadband Optical Constants and Nonlinear Properties of SnS 2 and SnSe 2 .

SnS ₂ and SnSe ₂ have recently been shown to have a wide range of applications in photonic and optoelectronic devices. However, because of incomplete knowledge about their optical characteristics, the use of SnS ₂ and SnSe ₂ in optical engineering remains challenging. Here, we addressed this problem by establishing SnS ₂ and SnSe ₂ linear and nonlinear optical properties in the broad (300-3300 nm) spectral range. Coupled with the first-principle calculations, our experimental study unveiled the full dielectric tensor of SnS ₂ and SnSe ₂ . Furthermore, we established that SnS ₂ is a promising material for visible high refractive index nanophotonics. Meanwhile, SnSe ₂ demonstrates a stronger nonlinear response compared with SnS ₂ . Our results create a solid ground for current and next-generation SnS ₂ - and SnSe ₂ -based devices.