Photonic Crystals |
A photonic crystal is aperiodic optical nanostructure thataffects the motion of photons in much the same way that ionic latticesaffect electrons insolids. Photonic crystals occur in nature in the form of structural coloration—and, in differentforms, promise to be useful in a range of applications. Photonic crystals canbe fabricated for one, two, or three dimensions. One-dimensional photoniccrystals can be made of layers deposited or stuck together. Two-dimensionalones can be made by photolithography,or by drilling holes in a suitable substrate. Fabrication methods forthree-dimensional ones include drilling under different angles, stackingmultiple 2-D layers on top of each other, direct laser writing, or, for example,instigating self-assembly of spheres in a matrix and dissolving the spheres. Photonic crystalscan, in principle, find uses wherever light must be manipulated. Existingapplications include thin-filmoptics with coatings for lenses. Two-dimensional photonic-crystal fibers are used innonlinear devices and to guide exotic wavelengths. Three-dimensional crystalsmay one day be used in opticalcomputers.