Thermally tuning of the photonic band gap of SiO2 colloid-crystal infilledwith ferroelectric BaTiO3

SiO2 colloid crystal infilled with BaTiO3 was synthesized by a process of s elf-assembly in combination of a sol-gel technique. It is found that infill ing of the fully crystallized BaTiO3 into the colloid assembly can enhance the photonic band gap significantly. In the vicinity of the ferroelectric p hase transition point of BaTiO3 (100-150 degreesC), the photonic band gap o f the assembly exhibits a strong temperature dependence. At the Curie point , the band gap has a 20 nm redshift, and the optical transmittance reaches its minimum. Such a temperature-tuning effect in the photonic band gap shou ld be of high interest in device applications. (C) 2001 American Institute of Physics.