The influence of the Talbot effect on the application performance of beam sampling grating in high power laser devices

The beam sampling grating (BSG) is one of the key optical components in Final Optics Assembly of high power laser devices. The output power of the laser device is monitored in real-time by online beam sampling. The physical experiment parameters are accurately obtained. During the operation of the high-power laser device, it was found that a grating also appeared on the surface of the optical component behind the grating surface. Its period is almost the same as that of the grating in front of it, and it is called a replica grating. This is a phenomenon that has never been reported before. In this paper, based on the beam-sampling grating structure of a high-power laser device, simulation analysis shows that the formation of the replica grating is highly related to the field enhancement caused by the Talbot effect. Offline validation experiments show the maintenance distance of the field enhancement induced by the Talbot effect. The results show that the Talbot effect will inevitably affect the components of Final Optics Assembly after BSG. The influence of grating replication on the sampling rate of the laser output is analyzed using the ray tracing method. The methods to stabilize the sampling rate and reduce the risk of laser damage are determined. The research results provide valuable guidance for the engineering application of beam sampling gratings in high power laser devices.