Polarization and power characteristics of pulsed dye lasers with transverse pumping

Starting from the classical theory on molecular luminescence in liquids, rate equation for two-polarization-mode laser oscillation under transverse pumping with intense excitation have been set forth neglecting the influence of orientational relaxation of the dye molecules. Hence, the laser output power and polarization under different configurations have been obtained. The results show that the dye laser is partially polarized even when the pump beam is unpolarized and no polarizing elements exist in the cavity. If we define a reference plane consisting of the axes of the pump beam and the dye laser, the laser system has to adopt the plane perpendicular to the reference plane as the polarization direction in order to yield a highly efficient, linearly polarized laser output. Experiments on a copper-vapor laser pumped dye laser verified these analytical results.