Synthesis, characterization, and applications of opals

Abstract Synthetic opals have been designed and demonstrated for a range of applications in photonics. Because they can exhibit a photonic stopband in transmission and reflection, opals can control light emission for frequencies within the specified stopband. They are used as decorative or functional coatings for structures such as waveguides or sensors and are usually characterized using optical measurements and electron microscopy. Both opals and inverse opals are readily fabricated in large areas using a variety of methods and materials and they are powerful tools to study the control of light at the nanoscale.