Synthesis and characterization of a photochromic sol–gel material functionalized with azo dye

An azo dye functionalized sol–gel material has been designed and synthesized to possess photochromism under a green laser beam illumination control. 10-mW laser illumination with a spot size of 1 mm2 at 532 nm wavelength on the film material was found to result in 6 × 10−4 change in material refractive index. The response time of the material photochromism is around 50 ms (3-dB modulation bandwidth of 20 Hz). Further optical transmission measurements reveal low optical absorption by the film material at 1.55 μm wavelength window. The investigation of a tunable waveguide Bragg grating device with the sol–gel material suggests a new promising platform candidate for the fabrication of all-optical controlled photonic devices.