Numerical Investigation of High-Purity Entangled Photon-Pair Generation in Ba3Mg3(BO3)3F3 Crystals

Donghwa Lee,Kwang Jo Lee,Ilhwan Kim

doi:10.3390/cryst10121164

Abstract

We investigate the high-purity entangled photon pair generation in a recently developed borate crystal, Ba3Mg3(BO3)3F3. The technique is based on the spontaneous parametric down-conversion under the extended phase matching (EPM), where the phase matching and the group velocity matching between the interacting photons are satisfied simultaneously in bulk crystals with point symmetry of orthorhombic mm2 (thus showing biaxial birefringence). We will discuss all the theoretical aspects required for the generation of photon pairs in mm2 biaxial crystals, which are much more complex than the cases of uniaxial crystals (e.g., β-BaB2O4 and LiNbO3) and periodically poled crystals that are widely used in the field. Our study includes theoretical and numerical investigations of two types of EPM and their corresponding effective nonlinearities and spatial walk-offs. The results show that two types of EPM are satisfied over the specific range in the direction of pump wave vector, corresponding to its spectral ranges of 876.15–1052.77 nm for Type I and 883.92–914.33 nm for Type II. The joint spectral analyses show that photon-pairs can be generated with high purities of 0.997 with a proper pump filtering (for Type II), and 0.833 even without pump filtering (for Type I).

Highlights

Photon-pair sources based on spontaneous parametric down-conversion (SPDC) in nonlinear optic χ(2) crystals are practical tools for experimental demonstrations of quantum metrology, quantum teleportation, quantum communication, and entanglement-based cryptography [1]
The results show that the calculated joint spectral amplitude (JSA) has a circular shape for Type II, and that photon-pairs can be generated with a high purity of 0.997 with a proper pump filtering
We have theoretically and numerically investigated the entangled photon-pair generation in a newly developed borate crystal, Pna21 -BMBF

Summary

Introduction

Photon-pair sources based on spontaneous parametric down-conversion (SPDC) in nonlinear optic χ(2) crystals are practical tools for experimental demonstrations of quantum metrology, quantum teleportation, quantum communication, and entanglement-based cryptography [1]. Mutailipu et al reported a new borate crystal, Ba3 Mg3 (BO3 ) F3 (or BMBF) that has two types of polymorphs: orthorhombic and hexagonal crystal systems, respectively [14] Of these two, the orthorhombic BMBF (the mm point symmetry, Pna21 ) exhibits a large laser damage threshold (~6.2 GW/cm2 ), a deep-UV cutoff edge (λ~184 nm), a weak anisotropic thermal expansion, and the insolubility in water (i.e., the non-hygroscopicity unlike the BBO). We will show that, in mm2-biaxial crystals, the EPM can be satisfied in a wide wavelength region (and in the specific range in the direction of pump wave vector), which is contrasted with the cases of the uniaxial crystals in Refs.

Material and Theories

Simulations and Discussion

Conclusions