Azobenzene polymer films for optical storage and high-order diffraction (I)

Abstract

The properties of phase conjugated (PC) beam and stable optical storage in an azobenzene polymer film were studied by degenerate four-wave mixing. With low-intensity incident waves (peak value of the pulses of the order of W/cm2), the PC beam as well as diffraction beams were observed and then disappeared after turning off one of the three incident beams. When the peak intensities of the incident beams reached the order of 10 W/cm2, the PC beam did not disappear but decreased to some extent after turning off the writing beams. As the peak intensities of incident beams increased to the order of 103 W/cm2, diffraction up to 4th-order was observed. When all of the three incident waves were turned on, three groups of high-order forward and backward diffraction beams were observed. Turning off two of the three incident beams, the diffraction beams of the other incident beams did not decrease obviously, i.e., stable optical storage was realized. After the experiments, brilliant hologram spot was observed and could be maintained over 120 days without obvious change.