SPDC single-photon source in Ti-indiffused diced ridge LiNbO ₃ 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 LiNbO 3 . 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 <0.4dBcm 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⋅10 5 1s⋅mW⋅nm, with a heralding efficiency of η h =45% ( η 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.