Widely tunable single photon source with high purity at telecom wavelength

TL;DR

This paper demonstrates a highly pure, widely tunable single-photon source at telecom wavelengths using SPDC in periodically poled KTiOPO4, with both theoretical predictions and experimental validation of spectral purity across key telecommunication bands.

Contribution

It introduces a method for generating highly pure, tunable photon pairs at telecom wavelengths with both theoretical modeling and experimental verification.

Findings

Purity of joint spectral intensity exceeds 0.98 across 1460-1675 nm.

Experimental measurements confirm high purity at specific telecom wavelengths.

The source is suitable for quantum communication applications.

Abstract

We theoretically and experimentally investigate the spectral tunability and purity of photon pairs generated from spontaneous parametric down conversion in periodically poled $\mathrm{KTiOPO_4}$ crystal with group-velocity matching condition. The numerical simulation predicts that the purity of joint spectral intensity ($P_{JSI}$) and the purity of joint spectral amplitude ($P_{JSA}$) can be kept higher than 0.98 and 0.81, respectively, when the wavelength is tuned from 1460 nm to 1675 nm, which covers the S-, C-, L-, and U-band in telecommunication wavelengths. We also directly measured the joint spectral intensity at 1565 nm, 1584 nm and 1565 nm, yielding $P_{JSI}$ of 0.989, 0.983 and 0.958, respectively. Such a photon source is useful for quantum information and communication systems.