UV irradiation-induced modification of photonic band gap and birefringence in artificial opal nanocomposite

A red shift of the photonic band gap and stress-induced birefringence have been observed in the bare and ZnO infilled artificial opal samples under UV laser irradiation. The stress-induced birefringence appeared between the irradiated and non-irradiated parts of the opal. These effects were related to the irradiation-stimulated increase in the density and the refractive index of the opal. Using the obtained results, the UV illumination-induced changes in the degree of polarization, volume and refractive index of the opal were estimated.