Ultrafast excitation of Bloch plasmon polaritons in hyperbolic metamaterials with an extreme ultra-violet transient grating

TL;DR

This paper demonstrates that a transient grating created by free-electron laser pulses can ultrafastly excite Bloch plasmon polaritons in hyperbolic metamaterials, enabling rapid optical mode control.

Contribution

It introduces a novel method using transient gratings for ultrafast excitation of Bloch plasmon polaritons in hyperbolic metamaterials, bypassing the need for nanostructured gratings.

Findings

Transient grating enables phase-matching for Bloch plasmon polariton excitation.

Finite element simulations confirm the role of the transient grating.

Method offers ultrafast control of optical modes in metamaterials.

Abstract

Manipulating materials properties with light drives advances in materials science and photonics. Hyperbolic metamaterials are promising candidates as next-generation quantum optical media. They support Bloch plasmon polaritons, which are characterized by potentially infinite wave-vectors and long lifetimes, but cannot be excited through direct light illumination due to momentum mismatch. Here, we experimentally show that a transient grating, formed via interference of fully coherent seeded free-electron laser pulses in a thin insulator film, enables the excitation of Bloch plasmon polaritons in an underlying hyperbolic metamaterial. Finite element simulations confirm the role of the transient grating in facilitating phase-matching and mode excitation. Our findings demonstrate a route to spatiotemporally excite Bloch plasmon polaritons modes, offering an alternative to permanently nanostructured gratings and potentially enabling ultrafast control of optical modes excitation.