A numerical solver for rate equations and photon transport equations in nonlinear laser spectroscopy

A software package, named PRES, is presented for the numerical solution of the coupled system of late equations and photon transport equation(s) which is useful in nonlinear UV/VIS/NIR laser spectroscopy investigating multiph oton processes of excitation and deactivation in the manifold of electronic excited states. By semidiscretization the system of partial differential e quations is transformed into two systems of ordinary differential equations . Because rate equations are often stiff and nonlinear they are solved with a modification of the A-stable trapezoidal rule. For the solution of the p hoton transport equations a special Runge-Kutta method is developed. (C) 20 00 Elsevier Science B.V. All rights reserved.