Atmospheric propagation of high-power supercontinuum lasers with thermal blooming

High-power supercontinuum (SC) lasers feature ultrabroad spectral bandwidth and high brightness, making them attractive for electro-optical applications involving atmospheric propagation. However, conventional propagation models typically approximate broadband sources as monochromatic or narrowband, leading to significant inaccuracies for SC lasers with spectral widths spanning hundreds to thousands of nanometers. In this work, we propose a line-by-line cumulative numerical method to model the atmospheric propagation of high-power SC lasers, explicitly accounting for wavelength-dependent absorption, extinction, turbulence, and thermal blooming. A non-coherent Gaussian Schell-model (GSM) superposition approach is employed to enable full-spectrum propagation analysis of broadband SC lasers. Based on this approach, the propagation characteristics of a representative high-power SC source are systematically analyzed. The results show that broadband cumulative absorption can produce significantly stronger thermal blooming effects than conventional monochromatic beams. Furthermore, several rapid evaluation parameters are introduced, including equivalent absorption and extinction coefficients, as well as an equivalent thermal blooming distortion parameter. After calibration using Strehl ratios, the equivalent thermal blooming distortion parameter exhibits good agreement with classical thermal-blooming experimental results. The proposed framework enables efficient prediction of propagation efficiency given known source parameters and provides a practical tool for performance assessment of broadband lasers in atmospheric environments.