Zarina Sadrieva

High- Q Supercavity Modes in Subwavelength Dielectric Resonators

We reveal that isolated subwavelength dielectric resonators support states with giant Q-factors similar to bound states in the continuum formed via destructive interference between strongly coupled eigenmodes and characterized by singularities of the Fano parameters.

High-Q resonances with low azimuthal indices in all-dielectric high-index nanoparticles

Recently, a novel class of high-Q optical resonators based on all-dielectric subwavelength nanoparticles with high refractive index has been proposed [M. V. Rybin, et al, arXiv:1706.02099, 2017]. Here we study a complex spectrum of such nanoscale resonators by means of the resonant-state expansion, treating the problem as a nonHermitian eigenproblem. We show that the high-Q features can be described within the mechanism of external coupling of open channels via the continuum. For ceramic resonators with permittivity ε = 40, we demonstrate that the quality factor of a trapped mode with a low azimuthal index could reach the value Q = 104 .

Photoluminescence behavior of nanoimprinted halide perovskite at low temperatures

Perovskite materials and bound state in the continuum are hot topics now. Development of these fields will lead to inventing advanced photonic devices. Here we report theoretical and experimental results for a high-Q cavity based on nanoimprinted perovskite film. We reveal that bound state in the continuum transformed into a resonant state due to leakage into substrate leads to significant enhancement of the photoluminescence signal of the perovskite cavity.

Effect of substrate on optical bound states in the continuum in 1D photonic structures

Optical bound states in the continuum (BIC) are localized states with energy lying above the light line and having infinite lifetime. Any losses taking place in real systems result in transformation of the bound states into resonant states with finite lifetime. In this work, we analyze properties of BIC in CMOS-compatible one-dimensional photonic structure based on silicon-on-insulator wafer at telecommunication wavelengths, where the absorption of silicon is negligible. We reveal that a high-index substrate could destroy both off-Γ BIC and in-plane symmetry protected at-Γ BIC turning them into resonant states due to leakage into the diffraction channels opening in the substrate.

Optical bound state in the continuum in the one-dimensional photonic crystal slab: Theory and experiment

In this work, we implement CMOS-compatible one-dimensional photonic structure based on silicon-on-insulator wafer supporting optical bound states in the continuum at telecommunication wavelengths - localized optical state with energy lying above the light line of the surrounding space. Such high-Q states are very promising for many potential applications ranging from on-chip photonics and optical communications to biological sensing and photovoltaics.