Conference Agenda

Real periodic arrays are finite, yet they are most often modeled as infinite. Here, we investigate finite-size eigenmodes of rectangular periodic arrays and their impact on the optical response. Experiments demonstrate optimal far-field coupling to finite arrays, while modal analysis reveals discrete resonance energies, manifesting as lasing sidebands. Finally, we experimentally demonstrate eigenmode engineering for applications such as mode cleaning.

Strong magnetic responses with extreme spatial and spectral confinement at optical frequencies are demonstrated in non-magnetic dielectric nanocylinders embedded in epsilon-near-zero (ENZ) Bragg microcavities. Hybridization between the cavity ENZ mode and the Mie resonances of the nanocylinders produces high-Q Bragg-Mie modes with effective near-zero permittivity and permeability, accompanied by strong magnetic field enhancement and near-perfect magnetic conductor behavior.

Optimized structures achieve Q-factors and magnetic Purcell enhancements on the order of 10^4 in an 18 micron-scale cavity, supported by analytical and numerical analysis. These results offer a route to multipolar-selective spectroscopy and lasing, low-threshold nonlinear optics, and engineered spontaneous emission.

High-Q resonances in photonic and metamaterial systems provide a powerful platform for invisibility, anapole states, and bound states in the continuum (BICs). In anapole-based structures, destructive interference between radiating multipoles suppresses far-field scattering while preserving strong near-field localization and high quality factors, enabling nonradiating resonances with enhanced energy confinement. This concept extends from classical dielectric and compound particles to quantum meta-atoms, where dynamic anapole states support low-radiation, strongly localized modes and open opportunities for giant superconducting qubits. Compound and modified multipole frameworks further clarify how multipolar interference, source displacement, and structural composition can be engineered to achieve selective or even total invisibility. In parallel, BICs offer an alternative route to extreme Q factors through symmetry protection and controlled coupling to the radiation continuum, as demonstrated in Babinet metamaterials with experimentally observed quasi-BIC resonances. Together, these studies show that high-Q nonradiating states, whether realized as anapoles, compound invisibility states, or BICs-form a unified foundation for advanced applications in cloaking, sensing, nonlinear optics, nanolasers, and quantum photonic devices.

Light–matter interaction in silica microparticles coated with molecularly thin J-aggregate layers is studied, a system that supports coupling between excitonic resonances and whispering gallery modes (WGMs). Angle and polarization resolved backscattering and photoluminescence measurements reveal systematic modifications of the WGM spectrum as a function of microparticle diameter and excitonic shell thickness. Fourier Image Spectroscopy (FIS) enables selective excitation of individual microparticles, showing reflectance minima and a depletion of WGM signatures consistent with WGM–exciton coupling. Complementary photoluminescence measurements exhibit enhanced emission at wavelengths and in plane momenta matching the identified WGMs. These results demonstrate that J-aggregate coated microparticles enable tunable WGM–exciton coupling and that FIS provides an effective approach for resolving their response with micrometre scale spatial selectivity.

Photonic crystals modify the emission properties of integrated emitters by altering the local density of states, thereby controlling the emission rate and directionality of spontaneous emission.

In this work, Zn-alloyed CsPbBr_3 nanocrystals (NCs), possessing high (96%) intrinsic quantum yield, are integrated into a one-dimensional photonic crystal (1DPhC) to investigate Bloch surface wave mediated emission enhancement and directionality. Polarized, 42-fold enhanced directional emission (<4 degree angular spread), along with an increased spontaneous emission rate, is observed when the NCs are embedded in the 1DPhC.

The development of sustainable optical materials has shifted focus toward biogenic architectures due to their intricate hierarchical structures, sustainability and biocompatibility. This study investigates the influence of the biogenic silica structures produced by the microalgae Coscinodiscus granii on the optical emission profiles of Rhodamine B (RhB) and Cyanine7 (Cy-7). C. granii is a microalgae that naturally produces segmented silica shells constituted by two valves interconnected by girdle bands that resemble slab photonic crystals (sPhC) featuring a square lattice of pores, both structurally and optically. In this study we used momentum-space spectroscopy to characterize the photophysical interactions between the organic dyes molecules and the sPhC. The preliminary results demonstrate spectral narrowing as emission couples to the photonic bands, while suppressing of radiative transitions is observed within the photonic bandgap. We attribute these changes to the radioative transition rate’s dependence on the local density of states (LDOS). These findings suggest that C. granii girdle bands serves as a promising platform for developing cheap eco-friendly bio-integrated photonic devices.