Bloch Surface Waves in Open Fabry-Perot Microcavities.

Thanks to the increasing availability of technologies for thin film deposition, all-dielectric structures are becoming more and more attractive for integrated photonics. As light-matter interactions are involved, Bloch Surface Waves (BSWs) may represent a viable alternative to plasmonic platforms, allowing easy wavelength and polarization manipulation and reduced absorption losses. However, plasmon-based devices operating at an optical and near-infrared frequency have been demonstrated to reach extraordinary field confinement capabilities, with localized mode volumes of down to a few nanometers. Although such levels of energy localization are substantially unattainable with dielectrics, it is possible to operate subwavelength field confinement by employing high-refractive index materials with proper patterning such as, e.g., photonic crystals and metasurfaces. Here, we propose a computational study on the transverse localization of BSWs by means of quasi-flat Fabry-Perot microcavities, which have the advantage of being fully exposed toward the outer environment. These structures are constituted by defected periodic corrugations of a dielectric multilayer top surface. The dispersion and spatial distribution of BSWs' cavity mode are presented. In addition, the hybridization of BSWs with an A exciton in a 2D flake of tungsten disulfide (WS2) is also addressed. We show evidence of strong coupling involving not only propagating BSWs but also localized BSWs, namely, band-edge and cavity modes.

Pulse modulation by Bloch surface wave excitation.

Considering dielectric multilayers with N identical bilayers and an additional terminating layer, we address the effect of Bloch surface wave excitation on the temporal characteristics of short optical pulses. When such a resonant excitation occurs within the spectrum of the incident pulse, the reflected pulse splits into leading and trailing parts, the latter having an exponentially decaying tail. The role of the number of bilayers and the level of absorption in the multilayer stack is illustrated.

Outlook on optical identification of micro- and nanoplastics in aquatic environments.

Plastic pollution in natural water bodies is an emerging problem that requires quick actions. Recently, the role of micro- and nanoplastics in pollution and health issues has been realized and taken seriously. In this paper, we have studied optical properties, such as NIR spectra and refractive index, of some common plastic materials and present a method and data to screen especially problematic transparent plastics with rough surface in aquatic environments. We also give an outlook of possible optical measurement methods that could be used for detection of micro- and nanoplastics.

Strip-loaded horizontal slot waveguide.

We introduce a novel concept for an optical waveguide called a strip-loaded slot waveguide. It allows an extraordinary confinement of the field in a waveguide with an extremely tiny (vertical) cross section. Unlike conventional slot waveguides, the proposed configuration has potential for very low propagation losses. Its operation is demonstrated at telecommunication wavelengths and, in addition, it is fabricated by means of mass production compatible techniques: atomic layer deposition and nanoimprint replication. The possibility to fabricate the proposed structure with such low-cost techniques opens a new path for a variety of nanophotonics applications.