CHEN Feng

(State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China)

Abstract: This paper has introduced the "play-of-color" effect and photonic crystal of opal and gemstone opal, the research status on photonic crystals of opal and inverted opal. Opal can be classified into various types including amorphous opal (opal-AG and opal-AN) and microcrystalline opal (opal-CT and opal-C). The SiO2 spheres in opal-AG or the lepispheres in opal-CT can form two-dimensional plates. The refractive index difference between the spheres and matrix forms the basis of optical diffraction of the precious opal. The characteristic "play-of-colour" phenomenon of the precious opal is caused by the diffraction because of various kinds of pure spectral colors in each colour zones within the opal and the colour transient resulted from the slight movement ore rotation of the sample or light source. Photonic crystalline opal is a new type of optical material which has artificial periodic dielectric structure characterized by a photonic band gap. Opal is a commonly used and cheap three-dimensional photonic crystal material and has attracted wide attention. Photonic crystals being combined with quantum materials have great application prospects in the fields of optics, optoelectronics, micron wave technology, quantum engineering, biological photonics, acoustics, and so on.

Keywords: opal; inverted opal; color; play-of-color; photonic crystal

ACTA MINERALOGICA SINICA Vol. 39, No.1, 2019, page 23-30