EFFICIENT OPTICAL-PHASE CONJUGATION IN METHYL-ORANGE-DOPED POLYVINYL-ALCOHOL FILM

An efficient optical phase conjugate (PC) wave in methyl-orange (MO)-doped polyvinyl alcohol (PVA) films by degenerate four-wave mixing (DFWM) is reported. As the wavelength concerned was far from the absorption center of the MO dye, a PC wave was generated more efficiently. For the configuration of mutually orthogonal-polarized pump and probe waves the PC reflectivity reached 30% at a wavelength of 531 nm and an intensity of 1 W/cm2 of a cw krypton-ion laser, by using a film with absorbance (= the product of the small-intensity absorption coefficient and the film thickness) of 2.1 at 531 nm. It was found that the photoinduced birefringence resulting from trans-cis isomerization, i.e., the real part of the nonlinear susceptibility chi2112, mainly contributed to generation of the PC wave at 531 nm.