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Coupled grating reflectors with highly angular tolerant reflectance

: Kroker, Stefanie; Käsebier, Thomas; Kley, Ernst-Bernhard; Tünnermann, Andreas


Optics Letters 38 (2013), No.17, pp.3336-3339
ISSN: 0146-9592
Journal Article
Fraunhofer IOF ()

We report on stacked high-contrast grating reflectors with virtually angular independent reflectance for transverse-magnetic polarized light. The investigated structure consists of two-layer pairs of amorphous silicon and silicondioxide that are designed for a wavelengths of 1550 nm. The large angular tolerance results from coupling of the two involved silicon gratings and is achieved if the modal fields in the reflectors are matched. With this approach, a reflectance of more than 96% in the entire angular spectrum is feasible. Experimentally we demonstrate a reflectance of more than 98% for incidence angles up to 60° and more than 90% up to 80°.