All-optical Mach-Zehnder modulator using a photochromic dye-doped polymer

An all-optical Mach-Zehnder modulator is demonstrated which is composed of a polymer waveguide doped with a photochromic dye in the core and a thick light blocking metal layer on it. The metal layer was opened on one arm of the Mach-Zehnder modulator, so that only one arm of the modulator could be irradiated by modulation light, thus allowing a differential phase shift. The optical modulator exhibited an extinction ratio of about -12 dB at a wavelength of 1.55 μm. A simple kinetic model developed to delineate the refractive index change in the dye-doped polymer film was applied to predict the evolution of the modulation characteristics.