Kazuo NAKAGAWA and Katunori KAWANO*

Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1, Mizumoto, Muroran, 050 Japan

(Received January 8, 1996; Accepted April 1, 1996)

The cause of the change in the optical path length δ(nd) of the saturable absorbing dye-doped polymer films under laser irradiation is investigated using polyvinyl alcohol and gelatin films doped with erythrosin B. The temperature rise of the dye-doped films, the changes in optical path length, film thickness, the refractive index and the optical density of the dye-doped films are measured under laser irradiation. The thermal expansion due to the temperature rise of the dye-doped films caused by the irradiation has greater effect on the δ(nd) than the fading of dye molecules due to the irradiation of laser beams.

Key words: dye-doped polymer films, saturable absorbing dye, phase-conjugate wave, change in optical path length, fading of dye molecules