Photonic bandgap effects were observed in particulate arrays of solution-derived SiO<sub>2</sub> particles prepared by the forced and unforced sedimentation of colloidal suspensions. The spectral shape of the bandgap is shown experimentally to correlate directly to the degree of microstructural order and is discussed by analogy to the x-ray diffraction of crystals, glasses, and glass–ceramics. An optical temperature sensor was made by use of the thermoptic differences between SiO<sub>2</sub> and an organic liquid infiltrated into the particle interstices. This provides the proof-of-concept that easily fabricated disordered structures, i.e., photonic glasses, can permit simple, even disposable, optical devices based on photonic band engineering.
© 2000 Optical Society of America
John Ballato, "Tailoring visible photonic bandgaps through microstructural order and coupled material effects in SiO2 colloidal crystals," J. Opt. Soc. Am. B 17, 219-225 (2000)