Noise Filtering for Highly Correlated Photon Pairs From Silicon Waveguides

Jong-Moo Lee,Wook-Jae Lee,Min-Su Kim,Jung Jin Ju

doi:10.1109/jlt.2019.2942436

Abstract

We fabricate silicon waveguide spirals and a ring resonator to generate photon pairs based on a spontaneous four-wave mixing. The coincidence-to-accidental-ratio (CAR) of photon pairs from the silicon waveguides is measured up to 400 after a noise-filtering by using the combination of bandpass filters and pump-rejection filters. The CAR is enhanced up to 700 by adding on-chip pump-rejection MZIs. We observe the CAR of the photon pairs from a silicon spiral is highly depending on the wavelength detuning from the pump wavelength. We discuss the noise sources related to the degradation of the CAR based on our experimental results.

Highlights

S ILICON photonics technology is an attractive candidate to realize a quantum information processing platform including a quantum-correlated photon-pair source [1]–[8], wavelength filters [9]–[13], and quantum interference circuits [14]– [16]
The photon pairs are relatively weak compared to the copropagating pump field and should be filtered by high-extinction pump-rejection filters (PRFs) to be useful for the quantum information processing
Three fiber-coupled 200 GHz optical bandpass filters (BPFs) with channel isolation over 40 dB per each and the insertion loss of 1 dB per each were connected in series and used to suppress the background photons from the laser diode (LD)

Summary

INTRODUCTION

S ILICON photonics technology is an attractive candidate to realize a quantum information processing platform including a quantum-correlated photon-pair source [1]–[8], wavelength filters [9]–[13], and quantum interference circuits [14]– [16]. We integrate on-chip cascaded MZIs following a silicon waveguide spiral on a single chip, and demonstrate the enhancement in CAR of the photon pairs up to 700 by adding the on-chip pump-rejection MZIs. We measure the variation of the CAR depending on the wavelength detuning from the pump and discuss the noise sources degrading the CAR including spontaneous Raman scattering (SpRS) [18]–[21] and other noise spectrum sources

EXPERIMENTAL SETUP

TRANSMISSION SPECTRUM OF MZI FILTERS

Photon-Pair Generation From a Ring Resonator

Noise by Spontaneous Raman Scattering

Noise Spectrum Close to the Pump Wavelength