Integrated Multichannel Lithium Niobate Waveguides for Quantum Frequency Conversion

In this paper, we demonstrate integrated photonic chips for multichannel quantum frequency conversion (QFC) based on reverse-proton-exchange periodically poled lithium niobate waveguides. The integrated chip is fiber coupled with two 34-channel fiber arrays, showing an average fiber-to-fiber sum-frequency generation (SFG) conversion efficiency of about 60% for multichannels. Then the same integrated chip is used to perform multichannel differential-frequency generation (DFG), showing the potential application in long-distance multimode quantum memory. Moreover, the integrated chip is utilized to construct a multichannel up-conversion detector, which has extensive applications including deep-space laser communication, high-rate quantum-key distribution, and single-photon imaging.