Frequency-definite photon pairs from a Lithium Niobate waveguide resonator

Kurzfassung

Quantum light sources that will be embedded in future quantum networks like for example in long distance communication need to fulfil a versatile range of requirements. Most importantly, low propagation losses and a good time synchronization between the remote nodes are required. Additional constrains will be provided by other hardware components like the quantum memories that so far exist only for narrow spectral bandwidths. We present here a pulsed quantum light source based on parametric down-conversion in a periodically-poled Lithium Niobate waveguide (PPLN-WG) resonator. The end facets of the PPLN-WG are coated with a high reflection coating forming a Fabry-Perot Resonator (FPR). Our source works at the well-established telecommunication C-Band and produces in pulsed operation photon pairs with a 2GHz bandwidth. Here, we present a thorough investigation of the FPR, its bandwidth, the group indices of the PPLN-WG, as well as the temporal pulse shapes of the photon pairs paving our way towards the generation of the time-bin entanglement.