Tunable nonlinear coherent perfect absorption with epsilon-near-zero plasmonic waveguides

TL;DR

This paper introduces a nanoscale nonlinear CPA scheme using epsilon-near-zero plasmonic waveguides, enabling tunable, ultrafast all-optical switching through enhanced Kerr nonlinearities at ENZ resonance.

Contribution

It presents a novel ENZ plasmonic waveguide design supporting nonlinear CPA with tunable, ultrafast switching capabilities at the nanoscale.

Findings

Achieves CPA at the ENZ cut-off frequency with two counter-propagating waves.

Demonstrates strong field enhancement boosts Kerr nonlinearities.

Enables ultrafast, tunable all-optical switching at the nanoscale.

Abstract

We propose a scheme to realize nonlinear coherent perfect absorption (CPA) at the nanoscale using epsilon-near-zero (ENZ) plasmonic waveguides. The general conditions to achieve CPA in a linear ENZ plasmonic waveguide are analyzed and presented. The proposed ENZ waveguides support an effective ENZ response at their cut-off frequency, where the CPA effect occurs under the illumination of two counter-propagating plane waves with equal amplitudes and appropriate phase distributions. In addition, the strong and uniform field enhancement inside the nanochannels of the waveguides at the ENZ resonance can efficiently boost Kerr nonlinearities, resulting in a new all-optical switching intensity-dependent CPA phenomenon which can be tunable with ultrafast speed. The proposed free-standing ENZ structures combine third-order nonlinear functionality with standing wave CPA interference effects in a nanoscale plasmonic configuration, thus, leading to a novel degree of tunable light-matter interactions achieved in subwavelength regions. Our findings provide a new platform to efficiently excite nonlinear phenomena at the nanoscale and design tunable coherent perfect absorbers.