Analog of photon-assisted tunneling originated from dark Floquet state in periodically modulated waveguide arrays

TL;DR

This paper theoretically demonstrates an analog of photon-assisted tunneling in periodically driven waveguide arrays, linked to dark Floquet states, which can be observed experimentally and used for light control.

Contribution

It introduces a new type of photon-assisted tunneling in waveguides driven periodically without static bias, connected to dark Floquet states, expanding understanding of light manipulation.

Findings

Analog of PAT achieved via periodic modulation of waveguides

PAT resonances exist in odd-numbered waveguide arrays

The effect is observable with current experimental setups

Abstract

We theoretically report an analog of photon-assisted tunneling (PAT) in a periodically driven lattice array without a static biased potential by studying a three-channel waveguide system. This analog of PAT can be achieved by only periodically modulating the top waveguide and adjusting the distance between the bottom and its adjacent waveguide. It is numerically shown that the PAT resonances also exist in the five-channel waveguide system and probably exist in the waveguide arrays with other odd numbers of waveguides, but they will become weak as the number of waveguides increases. With origin different from traditional PAT, this type of PAT found in our work is closely linked to the existence of the zero-energy (dark) Floquet states. It is readily observable under currently accessible experimental conditions and may be useful for controlling light propagation in waveguide arrays.