Patent ID: 6931045

Claim:
A distributed Bragg reflector exhibiting high reflectivity for photons of a predetermined energy E and a predetermined propagation axis, said reflector comprising a stacked plurality of repeat units, each repeat unit comprising a high-index layer, a first interlayer atop said high-index layer, a low-index layer atop said first interlayer, and a second interlayer atop said low-index layer, wherein: a) said high-index layer is composed essentially of a first material which is characterized by a first index of refraction, a first conduction band energy E c 1 , a first valence band energy E v 1 and a first electronic bandgap E b 1 , said first electronic bandgap E b 1 being greater than the predetermined energy E; b) said low-index layer is composed essentially of a second material which is characterized by a second index of refraction which is smaller than said first index of refraction, a second conduction band energy E c 2 , a second valence band energy E v 2 and a second electronic bandgap E b 2 , said second electronic bandgap E b 2 being greater than the predetermined energy E; c) said first interlayer has a thickness along said predetermined propagation axis not greater than about 10 nanometers, and is composed essentially of a first interlayer material which is characterized by a first interlayer conduction band energy E c IL1 and a first interlayer valence band energy E v IL1 , the energies E c IL1 -E v IL1 ; E c IL1 -E v 1 ; E c 1 -E v IL1 ; E c IL1 -E v 2 ; E c 2 -E v IL1 all being greater than said predetermined energy E; d) said second interlayer has a thickness along said predetermined propagation axis not greater than about 10 nanometers, and is composed essentially of a second interlayer material which is characterized by a second interlayer conduction band energy E c IL2 and a second interlayer valence band energy E v IL2 , the energies E c IL2 -E v IL2 ; E c IL2 -E v 1 ; E c 1 -E v IL2 ; E c IL1 -E v 2 ; E c 2 -E v IL1 all being greater than said predetermined energy E; and further wherein the combined optical thickness along said propagation axis of each repeat unit is nominally equal to one-half of the wavelength of said photons of a predetermined energy.