Giant resonant enhancement of optical binding of dielectric disks

TL;DR

This paper demonstrates giant resonant enhancement of optical binding forces between dielectric disks using resonant hybridized modes excited by counter-propagating Bessel beams, with force magnitudes reaching nanoNewton levels.

Contribution

It reveals how tuning aspect ratio and inter-disk distance induces resonance hybridization, significantly boosting optical binding forces beyond previous limits.

Findings

Resonance hybridization leads to high-Q modes with Mie-like morphology.

Optical forces up to nanoNewton scale are achieved with low-power Bessel beams.

Force magnitude and direction depend on the Bessel beams' longitudinal wave vector.

Abstract

Two-parametric variation over the aspect ratio of each disk and distance between disks gives rise to numerous events of avoided crossing of resonances of individual disks. For these events the hybridized anti-bonding resonant modes can acquire a morphology close to the Mie resonant mode with high orbital momentum of equivalent sphere. The $Q$ factor of such resonance can exceed the $Q$ factor of isolated disk by two orders in magnitude. We show that dual incoherent counter propagating coaxial Bessel beams with power $1mW/\mu m^2$ with frequency resonant to such a anti-bonding modes result in unprecedented optical binding forces up to decades of nano Newtons for silicon micron size disks. We show also that a magnitude and sign of optical forces strongly depend on the longitudinal wave vector of the Bessel beams.