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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.

We report the experimental observation of the UV-visible upconverted luminescence of bulk silicon under pulsed infrared excitation. We demonstrate that non-stationary distribution of excited carriers leads to the emission at spectral bands never to our knowledge observed before. We show that the doping type and concentration alter the shape of luminescence spectra. Silicon nanoparticles have a size between quantum-confined and Mie-type limits (10-100 nm) yet show increased luminescence intensity when placed atop a silicon wafer. The findings demonstrate that upconversion luminescence can become a powerful tool for nearest future silicon wafer inspection systems as a multimodal technique of measuring the several parameters of the wafer simultaneously.

Integrated photonics aims at on-chip controlling light in the micro- and nanoscale ranges utilizing the waveguide circuits, which include such basic elements as splitters, multiplexers, and phase shifters. Several photonic platforms, including the well-developed silicon-on-insulator and surface-plasmon polaritons ones, operate well mostly in the IR region. However, operating in the visible region is challenging because of the drawbacks originating from absorption or sophisticated fabrication technology. Recently, a new promising all-dielectric platform based on Bloch surface electromagnetic waves (BSWs) in multilayer structures and functioning in the visible range has emerged finding a lot of applications primarily in sensing. Here, we show the effect of multimode interference (MMI) of BSWs and propose a method for implementing the advanced integrated photonic devices on the BSW platform. We determine the main parameters of MMI effect and demonstrate the operation of Mach-Zehnder interferometers with a predefined phase shift proving the principle of MMI BSW-based photonics in the visible spectrum. Our research will be useful for further developing a versatile toolbox of the BSW platform devices which can be essential in integrated photonics, lab-on-chip, and sensing applications.