A thermal laser thruster depends on introduction of a high energy laser beam, absorption by the fluid propellant, confinement of the hot propellant gas with minimal losses, and conversion of thermal to kinetic energy in the nozzle. Based on thermodynamic constraints, efficient energy conversion is possible in either the subsonic Laser Supported Combustion (LSC) wave in a converging diverging nozzle or the supersonic Laser Supported Detonation (LSD) wave in a diverging nozzle configuration. A short discussion of both mechanisms is presented. Thruster modeling was performed. The results of steady laser heated LSD flows using LiH as propellant assuming finite rate chemistry are presented.