A passive nonresonant technique for pulse contrast enhancement and gain isolation

A passive aperture-scalable device is described which provides high contrast enhancement of a laser pulse over baseline optical noise while maintaining efficient net transmission of the principal laser pulse. The technique, which is based upon the nonresonant phenomenon of self-induced ellipse rotation, is capable of providing effective gain isolation for virtually any high-power laser system. The constrast enhancement capabilities of the device are demonstrated experimentally using a single ultrashort laser pulse obtained from a cavity-dumped passively mode-locked Nd : glass laser. In addition, a discussion is given concerning the ability of the device to temporally compress or stretch the optical pulse.