SPDC single-photon source in Ti-indiffused diced ridge LiNbO3 waveguides

Stable and bright single photon sources are key components for future quantum applications. A simple fabrication method is an important requirement for such sources. Here, we present a single photon source based on diced ridge waveguides in titanium indiffused LiNbO3. These waveguides can be easily fabricated by combining planar titanium in-diffusion without lithographic patterning and easy-to-handle precision dicing. Such devices have the potential to generate high single photon rates because ridge structures are typically less prone to the photorefractive effect. We achieve waveguide propagation losses <0.4 dB/cm and a SHG conversion efficiency of about 81 %/ Wcm(2). Harnessing a type-0 SPDC process to generate 1550 nm photons, we obtain a SPDC brightness of 3 <middle dot> 10(5) 1/s<middle dot>mW<middle dot>nm, with a heralding efficiency of eta(h) = 45 % (eta(h,wg) = 77.5 % for the waveguide itself excluded setup losses) and a heralded second-order correlation function of g(h)(2)(0)<0.003 at low pump powers. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement