The biaxial nonlinear crystal BiB3O6 as a polarization entangled photon source using non-collinear type-II parametric down-conversion

TL;DR

This paper characterizes the biaxial nonlinear crystal BiB3O6 (BiBO) as an efficient polarization entangled photon source via non-collinear type-II parametric down-conversion, demonstrating significant improvements over BBO.

Contribution

It provides a comprehensive analysis of BiBO's parameters for entangled photon generation and compares its performance to BBO, showing enhanced efficiency.

Findings

BiBO achieves higher entanglement rates than BBO.

Replacing BBO with BiBO increases generation rate equivalent to tripling pump power.

BiBO's properties are suitable for multiphoton entangled state generation.

Abstract

We describe the full characterization of the biaxial nonlinear crystal BiB3O6 (BiBO) as a polarization entangled photon source using non-collinear type-II parametric down-conversion. We consider the relevant parameters for crystal design, such as cutting angles, polarization of the photons, effective nonlinearity, spatial and temporal walk-offs, crystal thickness and the effect of the pump laser bandwidth. Experimental results showing entanglement generation with high rates and a comparison to the well investigated beta-BaB2O4 (BBO) crystal are presented as well. Changing the down-conversion crystal of a polarization entangled photon source from BBO to BiBO enhances the generation rate as if the pump power was increased by more than three times. Such an improvement is currently required for the generation of multiphoton entangled states.