Explanation

photonic crystal refers to the periodic arrangement of materials with different dielectric constant (or refractive index) in space, in which the dispersion curve of the light wave propagated will be banded. When the period of this spatial orderly arrangement is at the same order of magnitude compared with the wavelength of light, and the contrast of refractive index changes is large, "photonic band gap" (PBG) similar to semiconductor band gap may appear between bands, Electromagnetic waves with energy falling within the "photonic bandgap" are prohibited from propagating.

Classification