Manipulating light scattering and optical confinement in vertically stacked Mie resonators.

Area of Science:

• Nanophotonics
• Dielectric nanostructures
• Metamaterials

Background:

• High index dielectric nanoresonators offer low loss and tunable resonances, enabling novel optical states like bound-states in the continuum (BIC) and anapoles.
• Plasmonic systems suffer from higher losses compared to dielectric counterparts.
• AlGaAs/GaAs multilayer systems are suitable for fabricating high-performance nanophotonic devices.

Purpose of the Study:

• To investigate the optical properties of vertically stacked AlGaAs nanodisk Mie resonators.
• To engineer an anapole state in the visible wavelength region (400-700 nm).
• To explore the potential of these structures for enhanced light-matter interactions.

Main Methods:

• Fabrication of vertically stacked AlGaAs nanodisk resonators using charged sphere colloidal lithography.
• Optical characterization through reflectance spectra measurements.
• Numerical simulations using the finite difference time domain (FDTD) method.

Main Results:

• Vertically stacked AlGaAs nanodisks exhibit a sharp reflectance dip at the anapole wavelength.
• The reflectance dip contrast is enhanced in specular reflectance for 2 and 3 disk stacks due to an antenna effect.
• FDTD simulations reveal significantly enhanced field confinement (2-5 times greater than single disks) within the stacked nanodisks, increasing with stack height.

Conclusions:

• Vertically stacked AlGaAs nanodisk resonators are a promising platform for creating anapole states with enhanced light confinement.
• The demonstrated fabrication method is scalable and adaptable to various materials and wavelength ranges.
• These structures offer exciting opportunities for advanced linear and non-linear optical applications.