Dynamic characteristics of beam smoothing for three-dimensional spatiotemporal partially coherent light

Spatiotemporal partially coherent light (STPCL) has been introduced as a promising light source for beam-smoothing schemes to improve the uniformity of light intensity in high-energy laser systems. In this study, a three-dimensional STPCL model was constructed using the superposition of multi-transverse and multi-longitudinal modes to control the spectral bandwidth Δλ and far-field focal spot size α. Its smoothing dynamic characteristics and shaping ability were analyzed theoretically and numerically. The research results show that the far-field smoothing rate and the optimal effect irradiated by the STPCL strongly depend on Δλ. When the STPCL is combined with a continuous phase plate (CPP), the smoothing rate is primarily determined by Δλ, and the optimal smoothing effect depends on both Δλ and α, thereby significantly relaxing the strict requirements for Δλ. In addition, compared to traditional smoothing techniques that combine two-dimensional spectral dispersion smoothing (2D-SSD) with a CPP, the STPCL combined with CPP can simultaneously maintain the focal spot size and achieve superior uniformity with a faster smoothing rate by increasing Δλ and α. These findings can provide guidance and support for the development of next-generation high-power laser facilities.