based on an azobenzene, BFlAB, has been designed and synthesized. BFlAB readily forms an amorphous glass with a glass-transition temperature of 97 °C and exhibits photochromism in the amorphous solid film as well as in solution. The BFlAB amorphous film forms a surface relief grating with a high diffraction efficiency and a large modulation depth by irradiation with two coherent 488 nm Ar⁺ laser beams. (Y. Shirota et al., Adv. Mater. 2002, 14, 1157-1160)