Rubidium-doped KTiOPO4 waveguides as a dual-type photon-pair source

We investigate the dual generation of type-0 and type-II spontaneous parametric down conversions (SPDCs) within a single periodically poled rubidium-doped (PPRKTP) waveguide. By coupling a 45° linearly polarized pump laser into the waveguide, both SPDC processes are concurrently excited: type-0 SPDC process is facilitated via third-order quasi-phase matching (QPM) utilizing the nonlinear coefficient , while type-II SPDC process employs first-order QPM with the nonlinear coefficient . This dual-SPDC scheme holds potential for applications in quantum communication protocols targeting the telecommunication wavelength.