The refractive index n and the absorption constant K are numerically evaluated for fully ionized hydrogen plasmas as functions of the electron temperature T and atomic density N for the case of ruby, neodymium-glass, and CO2 laser radiation and for the second harmonics of each type of radiation on the basis of the two-fluid model of hydrodynamics using Spitzer's collision frequency. Limitations due to degeneration, too small Debye length, and non-linear effects are given. The absorption constant is compared with the values of the quantum theory of inverse bremsstrahlung without collective effects, and with the Dawson-Oberman theory.