Ultra-broadband non-degenerate guided-wave bi-photon source in the near and mid-infrared

TL;DR

This paper introduces an integrated Ti:LiNbO₃ waveguide source capable of generating ultra-broadband bi-photons spanning near- and mid-infrared wavelengths, suitable for advanced quantum metrology applications.

Contribution

The work demonstrates a novel integrated waveguide source producing broadband bi-photons with unmatched spectral bandwidth and dispersion engineering, expanding capabilities for quantum technologies.

Findings

Spectral bandwidth exceeds 25 THz.

Central wavelengths at 860 nm and 2800 nm.

Good agreement between experimental results and simulations.

Abstract

The latest applications in ultrafast quantum metrology require bright, broadband bi-photon sources with one of the photons in the mid-infrared and the other in the visible to near infrared. However, existing sources based on bulk crystals are limited in brightness due to the short interaction length and only allow for limited dispersion engineering. Here, we present an integrated PDC source based on a Ti:LiNbO$_3$ waveguide that generates broadband bi-photons with central wavelengths at $860\,\mathrm{nm}$ and $2800\,\mathrm{nm}$. Their spectral bandwidth exceeds $25\,\mathrm{THz}$ and is achieved by simultaneous matching of the group velocities and cancellation of group velocity dispersion for the signal and idler field. We provide an intuitive understanding of the process by studying our source's behaviour at different temperatures and pump wavelengths, which agrees well with simulations.