Epoxy-based Polymer Containing Imidazole-type Azo Chromophores for Integrated Waveguide Applications

In this work, an epoxy-based polymer containing 2-phenylazo-4, 5-dicyanoimidazole chromophores (BP-IZ-DC) was synthesized and characterized by spectroscopic methods. The polymer showed unusual photo-bleachable property and the refractive index of the polymer could be readily modified by irradiation with a laser beam at visible wavelength. The irradiation with a laser beam at 488 nm caused a much more significant change of the refractive index than irradiation with 532 nm laser light. Upon the irradiation with the laser beam (488 nm, 100 mW/cm2) for 1 h, the refractive index decreased from 1.6512 to 1.5802. By using the photo-bleachable azo polymer, channel waveguide was fabricated by light irradiation through a mask and the light-transmission ability of the waveguide was evaluated.