Broadband Spontaneous Parametric Downconversion in Reconfigurable Poled Linearly-Uncoupled Resonators

TL;DR

This paper demonstrates a reconfigurable resonator system that efficiently generates broadband photon pairs via spontaneous parametric down-conversion without dispersion engineering, suitable for integrated quantum photonics.

Contribution

It introduces a novel linearly uncoupled resonator design with nonlinear coupling via a Mach-Zehnder interferometer, enabling broadband and reconfigurable SPDC in integrated platforms.

Findings

Achieved pair generation rates up to 250 MHz/mW.

Demonstrated integrated pair generation over 170 nm bandwidth.

Enabled reconfiguration for 300 nm bandwidth covering multiple IR bands.

Abstract

In this letter, we study spontaneous parametric down-conversion (SPDC) in a periodically poled structure composed of two linearly uncoupled resonators that are nonlinearly coupled via a Mach-Zehnder interferometer. The device does not require dispersion engineering to achieve efficient doubly-resonant SPDC and, unlike the case of a single resonator, one can reconfigure the system to generate photon pairs over a bandwidth of hundreds of nm. We consider the case of SPDC pumped at 775 nm in a periodically poled lithium-niobate (PPLN) device compatible with up-to-date technological platforms. We demonstrate pair generation rates of up to 250 MHz/mW pump power for a single resonance and integrated pair generation rates of up to 100 THz/mW pump power over 170 nm. When properly reconfigured, a single device can efficiently generate over a bandwidth of some 300 nm, covering the S, C, L, and U infrared bands.