Using Laser-Based Optical Distribution to Achieve First Subpicosecond Multimodule Synchronization in Positron Emission Tomography System

As the time performance of the positron emission tomography (PET) detector itself continues to improve, the impact of multimodule synchronization precision on system-level time resolution becomes increasingly evident. Therefore, we propose a laser-based optical distribution synchronization method to achieve higher synchronization precision. Experiments were conducted based on the design, verifying that after the laser carries the reference signal, the additional time uncertainty is only 0.836-ps full-width at half-maximum (FWHM), and the output signal’s slew rate is over six times that of traditional solutions. After optical distribution, the synchronization precision between synchronous signals is 0.855-ps FWHM, with a delay variation range of 0.47 ps. This is an order of magnitude improvement over the precision and stability currently achievable. Moreover, the synchronization precision after 15 km of transmission is 2.34-ps FWHM. The laser-based synchronization method can improve the synchronization precision in the PET system and optimize its integration, and also has the potential to be valuable in ultralarge systems.