Hot-spots and gain enhancement in a doubly pumped parametric down-conversion process

TL;DR

This paper experimentally explores a doubly pumped parametric down-conversion process in a nonlinear crystal, revealing hot-spots and gain enhancements that facilitate the generation of multimode entangled states of light.

Contribution

It demonstrates the emergence of hot-spots and gain enhancement in a doubly pumped PDC process, enabling new pathways for multimode entanglement generation.

Findings

Bright hot-spots observed in shared pump modes.

Resonance condition enhances parametric gain.

Potential for generating multimode entangled states.

Abstract

We experimentally investigate the parametric down-conversion process in a nonlinear bulk crystal, driven by two non-collinear pump modes. The experiment shows the emergence of bright hot-spots in modes shared by the two pumps, in analogy with the phenomenology recently observed in 2D nonlinear photonic crystals. By exploiting the spatial walk-off between the two extraordinary pump modes we have been able to recreate a peculiar resonance condition, reported by a local enhancement of the parametric gain, which corresponds to a transition from a three-mode to a four-mode coupling. From a quantum point of view this opens the way to the generation of multimode entangled states of light such as tripartite or quadripartite states, in simple bulk nonlinear sources.