Directional optical parametric amplification in a hyperbolic metamaterial

TL;DR

This paper demonstrates directional optical parametric amplification in a hyperbolic metamaterial using a photonic crystal waveguide coupled with an excitonic reservoir, enabling efficient, robust, and controllable signal amplification at optical wavelengths.

Contribution

The study introduces a novel approach to optical parametric amplification using exciton-polaritons in a hyperbolic metamaterial waveguide, allowing directional control and robustness against defects.

Findings

Achieved efficient idler generation with continuous wave pumping.

Controlled the propagation direction of the idler by adjusting seed laser angle.

Confirmed experimental results align with mean-field numerical simulations.

Abstract

Optical parametric amplification (OPA) comprises essentially a nonlinear four-wave mixing process in which a "pump" and a "signal" field give rise to an "idler" field under certain phase-matching conditions. Here we use a photonic crystal waveguide strongly-coupled with an excitonic reservoir to generate this process between different guided modes at optical wavelengths. Differently from classical nonlinear optical crystals, where the pump and idler photons travel almost collinearly, our exciton-polaritons are naturally separated in the waveguide due to their opposite group velocities. Due to the high efficiency of the process we can generate the idler field of the parametric process by pumping with a continuous wave laser and choose its direction of propagation in the waveguide by adjusting the angle of incidence of the seed laser. We show the OPA process to be robust against surface defects of the waveguide and can lead to simple-to-fabricate devices compared to microcavities that take advantage of strong signal-idler correlations in a propagating geometry. Our results closely agree with mean-field numerical simulations.