A Modular CPA Simulator Unifying Free-Space and Fiber Dispersion

Optical pulses undergoing chirped-pulse-amplification (CPA) can traverse both free-space and optical fiber, yet most computational tools treat these domains separately and lack inverse design. We describe a modular CPA simulator under development that unifies free-space dispersion - such as Treacy (grating pair) and Martinez (grating-lens-grating) layouts - with fiber and fiber amplifier stages in a single forward/inverse workflow. For free-space, we implement wavelength-dependent paraxial propagation: spectral slices advance through an ABCD model including grating geometry and imaging optics, accumulating phase to estimate derivatives of group delay (spectral phase) and spatio-spectral effects (spatial chirp, pulse-front tilt). An inverse layer composes the forward model with search/local optimization to meet user targets (e.g., shorter pulses approaching the transform limit and reduced third-order dispersion), with result-reuse optimizations that make broad design sweeps practical. We report preliminary analytic checks (Treacy/Martinez unit tests, internal consistency tests) and outline a validation plan coupling to autocorrelator/FROG traces as the lab system comes online. This simulator aims to accelerate CPA design and enable principled inverse studies on lab-scale hardware.