User Guide

Developed for ultrashort laser filamentation modeling, Acherus is a (2+1)-spatiotemporal laser filamentation package for Python. It solves the Nonlinear Envelope Equation (NEE) for ultrashort laser pulses in optically transparent and dispersive media—gases (air), liquids (water), and solids (silica)—using the pseudo-spectral Fourier-Crank-Nicolson (FCN) method. The package computes the temporal evolution of the plasma electron density generated during propagation, as well as the pulse intensity, fluence, and width spatiotemporal profiles. Acherus enables accurate prediction and reproduction of numerical or experimental ultrashort laser filamentation scenarios under moderate input powers, providing a versatile tool for modeling a wide range of nonlinear optical phenomena, including supercontinuum generation, conical emission, and X-wave formation, among others.