Omnidirectional reflectivity

Winn JN, Fink J, Fan S, Joannopoulos JD (1998) Omnidirectional reflection from a onedimensional photonic crystal. Opt Lett 23 1573... 

Chigrin D.N., Lavrinenko A.V.,Yarotsky D.A.,Gaponenko S.V. OhsCTvation of total omnidirectional reflection from a one-dimensional dielectric lattice. Appl. Phys. A 1999 68 25-28 Divliansky I., Mayer T.S., HoUiday K.S., Crespi V.H. Fahrication of three-dimensional polymer photonic crystal structures using single diffraction element interference. Appl. Phys. Lett. 2003 82 1667-1669... 

Ha Y.K., Yang Y.C., Kim J.E., Park H.Y., Kee C.S., Lim H., Lee J.C. Tunable omnidirectional reflection bands and defect modes of a one-dimensional photonic band gap structure with liquid crystals. Appl. Phys. Lett. 2001 79 15-17... 

B Temelkuran, EL Thomas, JD Joannopoulos, Y Fink. Low-loss infrared dielectric material system for broadband dual-range omnidirectional reflectivity . Optics Letters, vol.26, no.l7, 1 Sept. 2001, pp. 1370-2. 

Another issue of interest is the angular dependence of reflection coeflftcient. For some structures, this dependence is very strong and large values of / are obtained only for near-normal incidence, thus furnishing surfaces with very high directivity of reflected light. The other pole are the surfaces offering near-omnidirectional or even fully omnidirectional reflectivity. 

DJ9. Chigrin, A.V. Lavrinenko, D.A. Yarotsky, S.V. Gaponenko, All-dielectric onedimensional ptaiodic structures for total omnidirectional reflection and partial spontaneous emission control. Lightwave Technol. J. 17(11), 2018-2024 (1999)... 

Z. Liu, J. Xu, Z. Lin, Omnidirectional reflection fiom a slab of uniaxially anisotropic negative refractive index materials. Opt. Common. 240(1), 19-27 (2004)... 

H. Da, C. Xu, Z. Li, Omnidirectional reflection fiom one-dimensional quasi-periodic photonic crystal containing left-handed material. Phys. Lett. A 345(4), 459-468 (2005)... 

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). 

Figure 13-9. (a) TEM images of a Ti02/Si02 omnidirectional reflector (top) and a microcavity resonator (bottom), both of which were fabricated by the sol-gel process, and (b) angle-dependent reflectance spectra of the omnidirectional reflectorfor both TE and TM modes (solid curves observed, dotted curves calculated) (Chen, 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. 

Fig. 2.38 Spectral reflectance of omnidirectional stack with 8 layer pairs for various incident angles, TM mode. Material pair is Si/Si02 (dielectric permittivity 11.958/2.1316), thickness 174 and 75 nm, respectively...

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. 

A light beam reflected from a difluse surface does not remain in the same plane, hut may be instead reflected omnidirectionally, i.e., in any spatial direction (e.g., [261]). Such behavior is ideally described by Lambert s cosine law. 

Fig. 5.2 LGPs with light reflecting elements, (a) LGP with omnidirectional MRq elements, (b) LGP with uniform light collimating prism array along the y-axis. (c) LGP with graded position linear prism along the x-axis...

Where Cx is the electromechanical conversion efficiency of the transducer, assumed here to be itsed both for transmission and reception hence raised to a power of two, S is the strength of the scatterer (how much incident energy it reflects back), and r is the range to the scatterer, assuming an omnidirectional transducer in a deep ocean. The power of the transmitter is spread out over a spherically expanding shell of area as it travels to the... 

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