5 ms·

Photonic Crystals: Semiconductors of Light – By Eli Yablonovitch (2001) [pdf]

• peter_d_sherman 4y ago
  >Light entering the holey material will refract through and partially reflect off the myriad internal interfaces between air and glass. The complex pattern of overlapping beams will reinforce or cancel one another out according to the light’s wavelength, its direction of travel through the crystal, the refractive index of the glass, and the size and arrangement of all the holes. Perfect cancellation in all directions for a narrow band of wavelengths is like the band gap for electrons in semiconductors: that band of light cannot propagate through the crystal. Modifying the band gap structure—for instance, by filling some holes—produces other effects, similar to what can be done by doping electronic semiconductors. Often a photonic crystal is made of an electronic semiconductor material, and so the crystal has both an electronic band gap and a photonic band gap." (PDF Page 4, Scientific American magazine article page 49) My opinion: The article is absolutely brilliant! Also -- it would be interesting to know if electronic band gaps and photonic band gaps are higher/lower octaves (frequencywise) of one another, and if not, their exact mathematical relationship (i.e., are they logarithmically related? What's the exact mathematical formula that relates them? Etc., etc.)