ASLD simulates ultra-short pulse amplifiers, multipass amplification, saturation effects of pump light absorption, temperature dependent cross sections, and 3-dimensional population inversion. It can accurately model output power and gain based on the pump configuration. ASLD incorporates effects like gain guiding and Kerr lensing, utilizing methods for beam shape simulation and ray tracing for defining pump light distribution. ASLD's pump light analysis accounts for pump light spectrum, polarization, and absorption within laser crystals, crucial for designing end- and side-pumped geometries.