The frequency response of a resonator is governed by the locations of its quasinormal modes in the complex frequency plane. The real part of the QNM determines the resonance frequency and the imaginary part determines the width of the resonance. For applications such as energy harvesting and sensing, the ability to manipulate the frequency, linewidth and multipolar nature of resonances is key. Here, we present a simple analytical tool to control the location and polarity of radially symmetric resonators.
Metasurfaces that are infiltrated with active materials, such as dyes or up-converting nano-particles, offer many advantages for novel lasing systems, such as high directionality and low lasing threshold. However, such metasurface lasers require the optimisation of two metasurface modes that are resonant at both the absorption and lasing wavelength bands. The absorption band also requires a weak angular dispersion to allow for a large acceptance angle for the absorption. Here we propose and numerically demonstrate a novel technique to quantity and optimise these bands. Our technique is based on symmetry analyses of the eigenmodes of the metasurface and allows us to optimise mode volume into the active media, as well as the directionality of the lasing emission.
We report on our work developing adaptive mesh refinement for nanophotonic simulations in COMSOL. We compare three adaptive mesh refinement strategies and find that a method based on a posteriori error estimation leads to a lower memory footprint and a decrease in wall-clock time for complex three-dimensonal nanophotonic structures.
Hybrid plasmonic-photonic cavities are promising structures for enhancing the emission of quantum emitters by increasing the Purcell factor. In this work, we investigate a novel hybrid structure with a nanoparticle-on-a-mirror configuration coupled to a dielectric photonic crystal. This configuration allows to obtain small mode volumes due to the metallic nanoparticle and large Q-factors due to the photonic crystal. We report Purcell factors larger than $10^{5}$ in the visible spectral region, which are achieved with structures that are experimentally feasible with current technology. We expect that our results may open new avenues for boosting light-matter interactions in nanophotonic systems.
We consider the series-connected Josephson transmission line (JTL), constructed from Josephson junctions, capacitors and resistors. We calculate the velocity of shocks in the discrete lossy JTL. We propose the simple wave approximation, which decouples the continuum JTL equations into two separate equations for the right- and left-going waves. The approximation, in particular, allows to easily consider the formation of shocks.
