Nonlinear Bragg mirror made from a silicon phthalocyanine/methyl methacrylate copolymer

A nonlinear Bragg mirror based on saturably absorbing nonlinear-optical polymers is proposed and demonstrated. The saturable absorber is a copolymer of silicon phthalocyanine with methyl methacrylate, which exhibits its largest nonlinear absorption near 670 nm. A 23-layer stack was made by spin coating, with polymethyl methacrylate as the low-index layer, and the linear-optical performance was found to agree reasonably well with predictions based on a modified two-level model of the optical properties of the copolymer. Optical limiting at an intensity of 5-10 MW/cm(2) was demonstrated for 6-ns pulses at a wavelength of 688 nm.