Conference Agenda

The integration of large-area and transparent all-dielectric metasurfaces capable of sustaining photonic bound states in the continuum (BICs) with biomolecular recognition elements such as aptamers and molecularly imprinted polymers (MIPs) presents a promising avenue for achieving ultrahigh sensitivity in biosensing applications. BICs, distinguished by their infinitely high Q-factors and non-radiative nature, offer exceptional opportunities for enhancing light-matter interactions, thereby enabling unparalleled sensitivity to minute variations in refractive index. By leveraging the unique properties of BICs within photonic crystal slabs and coupling them with selective recognition elements, we aim to develop highly selective and sensitive biosensing platforms capable of detecting these analytes at trace levels, even at pico- and femtomolar concentrations. Here we present recent results regarding BIC-based biosensors in detecting and quantifying various biomolecules, including proteins and toxins in food. Furthermore, we present a novel sensor platform that enhances the BIC sensing principle with a MIP cladding layer tailored for specific binding to transforming growth factor-beta (TGF-β), a pivotal cytokine involved in diverse cellular processes. These advancements represent a significant stride in biosensing technology, offering versatile and efficient platforms with broad applications across scientific, industrial, and societal domains.

Achieving a robust chiral response in plasmonic metasurfaces is among key goals of current nanophotonic research. In this work, we theoretically show that the circular dichroism (CD) of a metal metasurface can be maximized by exploiting the concept of a bound state in a continuum (BIC) together with symmetry breaking. We consider a gold metasurface with a deformation of circular holes into oval holes. The chiral response at small values of the angle of incidence is dominated by a quasi-BIC, with nearly maximal values of the absorption CD that are almost independent of the deformation. Strong emission CD is also demonstrated. Symmetry analysis and mode profiles show that the extrinsically chiral response does indeed follow from a symmetry-broken BIC, and is associated with a strong enhancement of the local electrical field. The concept of a plasmonic BIC with symmetry breaking provides a robust pathway to increase the chiral response in metal metasurfaces and opens research opportunities in chiral plasmonics that combine narrow resonances with local field enhancement.

While the classical concept of phase of a coherent oscillation is a well defined notion, many attempts to describe its quantum mechanical counterpart failed. Here, we show a nouvel formulation of the quantum phase operator, which encompass previous problems and can be applied to any oscillatory system, as mechanical oscillator or electromagnetic field. Our formulation starts from a two-dimensional harmonic oscillator, and uses development by Newton’s binomial identity to action of the operator on any Foch state or linear combination of Foch states. We also introduce a physical interpretation of non-integer state number of the harmonic oscillator, overcoming a major limitation for the interpretation of the previous suggested forms of the phase operator. Applications of this novel approach to monomode displaced gaussian beam and doubled displaced states are also shown. Our formulation of the quantum phase operator bypasses the requirement of P, Q, or Wigner representation in the phase space and can be directly applied to Fock states. This approach offers a convenient mathematical framework for manipulating and analyzing phase properties in uantum systems.