Determination of the absorption and radiative decay rates of dark and bright plasmonic modes

Thermally controllable Mie resonances in a water-based metamaterial

Active control of metamaterial properties is of great significance for designing miniaturized and versatile devices in practical engineering applications. Taking advantage of the highly temperature-dependent permittivity of water, we demonstrate a water-based metamaterial comprising water cubes with thermally tunable Mie resonances. The dynamic tunability of the water-based metamaterial was investigated via numerical simulations and experiments. A water cube exhibits both magnetic and electric response in the frequency range of interest. The magnetic response is primarily magnetic dipole resonance, while the electric response is a superposition of electric dipole resonance and a smooth Fabry–Pérot background. Using temporal coupled-mode theory (TCMT), the role of direct scattering is evaluated and the Mie resonance modes are analyzed. As the temperature of water cube varies from 20 °C to 80 °C, the magnetic and electric resonance frequencies exhibit obvious blue shifts of 0.10 and 0.14 GHz, respectively.

Determination of complex Hermitian and anti-Hermitian interaction constants from a coupled photonic system via coherent control

By manipulating the relative amplitude and phase between two incoming lights, coherent control of photonic systems can be realized. Here, we show by temporal coupled mode theory and finite-difference time-domain simulation that a coupled system can be actively controlled to exhibit plenty of different spectral, angular, and excitation behaviors. Electromagnetically induced transparency-like and Fano spectral characteristics as well as strong beam steering have been observed. Remarkably, by selectively exciting the coupled modes, we have developed a new approach to determine the complex Hermitian and anti-Hermitian interaction constants. We find the constants are strongly geometric and material dependent and they are of importance in understanding the non-Hermitian physics arising from the dissipative, open coupled system.

Determination of the excitation rate of quantum dots mediated by momentum-resolved Bloch-like surface plasmon polaritons

When light emitters are being placed in close proximity to a plasmonic system, not only the emission but also the excitation can be strongly enhanced and both yield the surface plasmon polariton (SPP) mediated fluorescence enhancement. Here, we combine the rate equation model and coupled mode theory to formulate the excitation rate of light emitters located on a periodic metallic array. The rate is expressed in terms of quantities that can be measured by angle- and polarization-resolved reflectivity and photoluminescence spectroscopy. As a demonstration, we have studied the excitation rate of CdSeTe quantum dots deposited on a 2D Au nanohole array as a function of the propagation direction of the (-1,0) Bloch-like SPPs. At the excitation wavelength of 633 nm, we find the rate remains almost constant at ~44 ps^-1 regardless of the propagation direction of SPPs, which move from the Γ-X towards the Γ-M direction in the first Brillouin zone, and the crossing of the (-1,0) and (0,-1) SPPs along the Γ-M direction where two bright and dark modes are formed. The results are supported by the finite-difference time-domain simulations. We conclude the excitation rate is an intrinsic parameter and the enhanced excitation of the quantum dots arises entirely from field enhancement.