Omnidirectional mirrors

David Ariza-Flores A, Gaggero-Sager LM, Agarwal V (2012) White metal-like omnidirectional mirror from porous silicon dielectric multilayers. Appl Phys Lett 101 031119... 

Xifre-Perez E, Marsal LF, Ferre-Borrull J, Pallares J (2006) Confinement in a planar waveguide with porous silicon omnidirectional mirrors as confining walls. J Lumin 121(2) 301-303... 

S. Bains, Dielectric stack can be used as omnidirectional mirror , OE Reports, p. 3, June 1999. 

The concept of omnidirectional mirrors, also denoted as perfect mirrors, was introduced in 1998 [247, 248]. These are one-dimensional, all-dielectric mirrors (ID photonic crystals) that keep their reflective properties even for large oblique incident angles in a wide and fully tailorable range of frequencies. 

Basically, omnidirectional mirrors are dielectric quarterwave stacks in which TIR and Bragg mirroring wavelength ranges overlap, i.e., an overlapping band gap regime exists that extends above the light cone. 

Hart S. D., Maskaly G. R., Temelkuran B., Prideaux P. H., Joannopoulos J. D., Fink Y. External reflection from omnidirectional dielectric mirror fibers Science 296, 510 (2002). 

Dowling JP (1998) Mirror on the wall you re omnidirectional after all Science 282 1841-1842 Fabian J, Nakazumi H, Matsuoka M (1992) Near-infrared absorbing dyes. Chem Rev 92 1197-1226... 

Pure metal mirrors are omnidirectional reflectors, but the price to pay are their non-negligible absorption losses. On the other hand, all-dielectric multilayers exhibit very high reflectivity, but their reflectivity drops for oblique incident angles. Thus the idea occurs to combine both into a single structure. 

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