Portable system integrated with time comparison, ranging, and communication

We demonstrate a portable system integrated with time comparison,absolute distance ranging,and optical communication(TRC)to meet the requirements of space gravitational wave detection.A 1 km free-space asynchronous two-way optical link is performed.The TRC realizes optical communication with 7.7×10^(−5) bit error rate with a Si avalanche photodiode singlephoton detector,while the signal intensity is 1.4 photons per pulse with the background noise of 3×10^(4) counts per second.The distance measurement uncertainty is 48.3 mm,and time comparison precision is 162.4 ps.In this TRC system,a verticalcavity surface-emitting laser diode with a power of 9.1μW is used,and the equivalent receiving aperture is 0.5 mm.The TRC provides a miniaturization solution for ultra-long distance inter-satellite communication,time comparison,and ranging for space gravitational wave detectors.