Quarter-wave stacks may be designed to reflect both polarizations of a specific wavelength band at all angles of incidences (omnidirectional). Expressions are given for beth the omnidirectional band center wavelength and the bandwidth for selected values of the low- and the high-refractive-index layer values, It is shown that selecting the low refractive index near 1.45 maximizes the omnidirectional bandwidth for any value of the high refractive index. It is also shown that the omnidirectional bandwidth may be extended by addition of contiguous quarter-wave stacks.
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