Portable system integrated with time comparison, ranging, and communication

Abstract

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 9.1 μW 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.

Mitigation of the impact of Doppler shift on ranging accuracy

“…The continuous improvement of timing tools promotes the advancement of scientific research, and in turn, the progress of scientific research continuously enhances the performance of timing tools. Nowadays, many fields such as navigation and positioning, very long baseline interferometry, gravitational wave detection, and fundamental research require a unified time reference [1][2][3][4][5] . Time-frequency synchronization serves as a means to establish a unified time reference by leveraging high-precision and high-accuracy timing tools interconnected through optical fiber or free-space links.…”