Photochromic dye is expected for all-optical waveguide switches because it could change its refractive index by UV or
visible light irradiation. One of photochromic amorphous molecular materials, 4-[bis(9,9-dimethylfluorene-2-yl)amino]
azobenzene (BFlAB) readily formed stable amorphous glasses above room temperature without polymer dilution and it
showed large refractive index change and good processability. We fabricated an all-optical 1 × 2 Y-branch waveguide
switch by simple process and evaluated its optical properties and switching function.