Multiphoton-induced periodic microstructures inside bulk polymers by multibeam femtosecond laser interference

Abstract

We report on multiphoton-induced periodic microstructures inside bulk polymers by multibeam interference of femtosecond laser pulses at a wavelength of 800 nm, which is out of the absorption range of the polymer sample. Two-dimensional structures and three-dimensional periodic microstructures were fabricated inside bulk azodye-doped polymethylmethacrylate by four-beam interference and five-beam interference, respectively. The Raman spectra measurements for the photoinduced area of the sample before and after irradiation with the writing light showed that the periodic microstructures probably arose from photoinduced decomposition reaction of azodye molecules through multiphoton absorption. Two-dimensional and three-dimensional periodic microstructures were also fabricated in photopolymerization by four-beam and five-beam laser interference, respectively.