A high-precision detection method for laser time transfer based on a single-photon avalanche detector array

Space-ground laser time transfer is of significant importance to effectively function a high-precision time synchronization system. Instead of the single-pixel single-photon avalanche detector (SPAD) commonly used in the laser time transfer system, the SPAD array device is capable of supporting the greater performance of the signal photon capture. In this paper, it is experimentally demonstrated that the detection precision and time deviation (TDEV) of the SPAD array can be extremely improved by an order of magnitude compared with those of a single-pixel SPAD. As a result, 2.4 ps root mean square precision and 0.25 ps over an averaging time of 1000 s TDEV are achieved for the SPAD array, providing a new detection method for high-precision laser time transfer applications, such as space-ground optical clocks.