Variable attenuator for intense unpolarized laser beams

Utilization of polarizing optics for dynamic attenuation of intense unpolarized laser beams is reported. The new family of variable attenuator is composed of a retardation plate mounted between two identical polarization splitters placed in tandem. By varying the retardation, or by rotating the plate, the transmission is varied. These attenuators are characterized by a high transmission and a high optical damage threshold. A transmission dynamic range as large as 1 to 10(-5) is achievable with polarization splitters made of crystals such as sapphire. These attenuators are applicable in laser material processing and in Q switching of unpolarized lasers.