Conference Agenda

We present and discuss the experimental and theoretical performances of Cavity Resonator Integrated Grating Filters (CRIGFs) with a specific focus on their active tuning through effective index control of the guided mode. In particular, we show that Quantum-Confined Stark Effect in quantum wells embedded in the active waveguide provides an efficient tuning of the resonance, opening the way to fast and agile optical filters and waveguide couplers.

We experimentally demonstrate the generation of phase-locked ultrafast laser pulses in metallic nanoparticle lattices coupled to optically pumped organic fluorescent molecules. Cross-correlated frequency-resolved optical gating measurements show that the emitted pulses exhibit picosecond scale durations with sub-picosecond temporal modulation. Complementary finite-difference time-domain simulations incorporating a four-level gain medium indicate that the modes of the lattice become phase-locked due to shared excited state populations near the nanoparticles.

Frequency conversion in epsilon near zero (ENZ) metasurfaces has been demonstrated via self-phase modulation and adiabatic frequency conversion. In this work, we report the first observation of cross-phase modulation in a time-varying ENZ-metasurface which has been designed to exhibit two well-defined absorption bands on both sides of the ENZ region. Under oblique-incidence excitation in these bands, we report large, tunable, and broadband

frequency translation at lower pump energy. We also demonstrate that exciting this particular metasurface outside the ENZ region induces the time-varying, distinct nonlinear phase shifts by enhancing the nonlinearity in the system. Our results can potentially provide insights into designing an efficient time-varying metasurface for the phase modulation of ultrafast light.

Enhanced epsilon near zero (eENZ) metamaterials based on resonant ENZ–dielectric multilayer stacks provide a powerful platform for controlling the properties of light. Unlike effective medium ENZ structures, these stratified metamaterials exploit Fabry–Pérot resonances, guided modes, and plasmonic excitations to strongly enhance transmission, reflection, or absorption near the ENZ wavelength while mitigating intrinsic material losses. The design and principles of eENZ structures are reviewed together with their theoretical capabilities. Previously reported fabrication of eENZ structures from indium tin oxide and titanium dioxide thin films is discussed and their experimentally demonstrated capabilities are assessed. The eENZ metamaterial may be positioned as a versatile building block for novel active and reconfigurable photonic systems.

Optical anapoles have attracted significant interest due to their ability to confine light in subwavelength structures. However, most of their experimental realizations suffer from parasitic scattering, which deteriorates their local field enhancement and spectroscopic signatures. Here, by using scattering-current multipole expansion, we identify the configurations of localized currents that lead to the parasitic scattering. In particular, for the case of anapole excitations in thin dielectric disks, we explicitly show that the toroidal dipole moment, which is necessary to cancel the outgoing electric-dipole radiation, is composed of current octupoles that produce significant magnetic-quadrupole radiation. We propose a nonlinear excitation scheme to minimize this contribution, opening a way to the realization of perfect optical anapoles.