Switching Purcell effect with nonlinear epsilon-near-zero media

TL;DR

This paper demonstrates that strong Kerr nonlinearity at epsilon-near-zero frequencies enables ultrafast topological transitions in metamaterials, allowing dynamic control of spontaneous emission and Purcell effect with sub-picosecond switching.

Contribution

It introduces a theory of enhanced nonlinear response in ENZ media and shows ultrafast, polarization-dependent topological transitions affecting emission control.

Findings

Purcell factor can be modulated by nearly a factor of three at ENZ frequencies.

Ultrafast switching of the Purcell effect occurs on sub-picosecond timescales.

Nonlinear effects are stronger for p polarization and nearly angle-independent.

Abstract

An optical topological transition is defined as the change in the photonic isofrequency surface around epsilon-near-zero (ENZ) frequencies which can considerably change the spontaneous emission of a quantum emitter placed near a metamaterial slab. Here, we show that due to the strong Kerr nonlinearity at ENZ frequencies, a high power pulse can induce a sudden transition in the topology of the iso-frequency dispersion curve, leading to a significant change in the transmission of propagating as well as evanescent waves through the metamaterial slab. This evanescent wave switch effect allows for the control of spontaneous emission through modulation of the Purcell effect. We develop a theory of the enhanced nonlinear response of ENZ media to s and p polarized inputs and show that this nonlinear effect is stronger for p polarization and is almost independent of the incident angle. We perform finite-difference time-domain (FDTD) simulations to demonstrate the transient response of the metamaterial slab to an ultrafast pulse and fast switching of the Purcell effect at the sub-picosecond scale. The Purcell factor changes at ENZ by almost a factor of three which is an order of magnitude stronger than that away from ENZ. We also show that due to the inhomogeneous spatial field distribution inside the multilayer metal-dielectric super-lattice, a unique spatial topological transition metamaterial can be achieved by the control pulse induced nonlinearity. Our work can lead to ultra-fast control of quantum phenomena in ENZ metamaterials.