Synchronized Fiber Lasers for Efficient Coincidence Single-Photon Frequency Upconversion

We experimentally demonstrate a compact synchronized fiber laser system that enables fast and efficient coincidence single-photon frequency upconversion detection. Robust synchronization between the pump and signal pulses was achieved with a long-term stability. Moreover, the synchronized pulses were wellmatching in both of the time and spectrum domains. As a result, a coincidence single-photon frequency upconversion was realized with a conversion efficiency of 91.8% and low background counts around 2.8 × 10³ s^-1.