Lithium Niobate On Insulator (LNOI) has recently emerged as a promising platform for the realization of electro-optically reconfigurable waveguides combining small footprint and ultra-low propagation loss. Integration of these components with superconducting nanowire single photon detectors (SNSPDs) opens up the possibility to perform on-chip manipulation and detection of quantum states of light in a physically stable and scalable architecture. Here we report recent theoretical and experimental progress towards the realization of fast electro-optic modulators compatible with cryogenic temperatures and high-performance NbTiN superconducting nanowires single-photon detectors (SNSPDs) monolithically integrated in LNOI waveguides.
We demonstrate an amorphous molybdenum–rhenium (MoRe) film on a thin-film lithium niobate substrate as an efficient superconducting nanowire single-photon detector (SNSPD) operating at T = 2.5 K. MoRe films were deposited by DC magnetron sputtering with a composite target of 56 at. % Mo and 44 at. % Re on lithium niobate on insulator substrates at room temperature. We investigated the spectral and temporal performance of MoRe SNSPDs as well as the detection regimes of one and multiple photons. The fabricated detector with a nanowire width of about 150 nm shows an internal detection efficiency of approximately 98% and 73.5% for the most crucial wavelengths for integration on the chip, 780 and 1550 nm, respectively. Our results show great potential for the use of MoRe for scalable and cryogenic tunable quantum photonic integrated circuits.