Giant Generation of Polarization-Entangled Photons in Metal Organic Frameworks*

Organic crystals have been extensively studied as possible candidates for nonlinear optics due to their high nonlinear response, however due to their non-covalent bonds, these materials are prone to be unstable at strong laser intensities, which are necessary to study nonlinear optical effects. On the other hand, metal organic-frameworks (MOFs) crystals have been highlighted as possible candidates for nonlinear optics, due to their high nonlinear response values and covalent coordination bonds [2]. To analyze this crsytals we use a multi-scale methodology to study spontaneous parametric down-conversion (SPDC) of visible light using MOFs[1]. For a set of experimentally relevant zinc-based MOF crystals, we theoretically explore the phase-matching conditions for the generation of polarization-entangled photons via collinear degenerate type-II SPDC. For a single-mode 1D waveguide geometry, entangled pair generation rates of  are predicted at 1064 nm, outperforming the conversion efficiency of equivalent periodically-poled KTP waveguides by a factor of 1.6 [3]. Our work opens the way to new crystals for use in nonlinear optics, as well as generating a scalable algorithm that can be used to study new crystals.

[1] Sanoj Raj et al. First-Principles Screening of Metal-Organic Frameworks for Entangled Photon Pair Generation. preprint, 2023

[2] Ruben A. Fritz, et al. Engineering entangled photon pairs with metal–organic frameworks. Chem. Sci., 12:3475–3482, 2021.

[3] James Schneeloch, et al. Introduction to the absolute brightness and number statistics in spontaneous parametric down-conversion. Journal of Optics, 21(4):043501, feb 2019