Temperature insensitive type II quasi-phasematched spontaneous parametric downconversion

TL;DR

This paper demonstrates a method for achieving temperature-insensitive type II SPDC in KTP, enabling stable entangled photon sources for telecommunications applications, with both theoretical calculations and experimental validation.

Contribution

The study introduces a novel approach to reduce temperature sensitivity in type II SPDC using KTP, supported by calculations and experimental demonstration.

Findings

Temperature-insensitive degenerate emission at 1326nm observed

The effect maximizes around 1165nm wavelength

Practical polarization entangled photon source demonstrated

Abstract

The temperature dependence of the refractive indices of potassium titanyl phosphate (KTP) are shown to enable quasi-phasematched type II spontaneous parametric downconversion (SPDC) with low temperature sensitivity. Calculations show the effect to be maximised for emission of photons at around 1165nm, as well as producing potentially useful regions for wavelengths throughout the telecommunications bands. We demonstrate the effect experimentally, observing temperature-insensitive degenerate emission at 1326nm, within the telecommunications O band. This result has practical applications in the development of entangled photon sources for resource-constrained environments, and we demonstrate a simple polarization entangled source as a proof of concept.