Harmonic Generation in Multi-Resonant Plasma Films

TL;DR

This paper demonstrates highly efficient second and third harmonic generation in plasma-resonant films, enabling low-threshold nonlinear processes in ultra-compact structures despite losses and phase mismatch.

Contribution

It introduces a novel approach to harmonic generation using plasma resonances in thin films, achieving high efficiency in structures much shorter than traditional nonlinear crystals.

Findings

High harmonic conversion efficiency achieved at low irradiance.

Harmonic generation occurs in structures 10^4 times shorter than conventional crystals.

Effective nonlinear processes despite losses and phase mismatch.

Abstract

We investigate second and third harmonic generation in a slab of material that displays plasma resonances at the pump and its harmonic frequencies. Near-zero refractive indices and local field enhancement can deplete the pump for kW/cm2 incident powers, without resorting to other resonant photonic mechanisms. We show that low-threshold, highly-efficient nonlinear processes are possible in the presence of losses and phase-mismatch in structures that are 104 times shorter than typical KDP or LiNbO3 crystals, for relatively low irradiance values.