title: Porous silicon-based rugate filters.
abstract: We report an experimental study of porous silicon-based rugate filters. We performed filter apodization, following a half-apodization approach, which successfully attenuated the sidelobes at both sides of the photonic stop band. We achieved successful reduction of interference ripples through the insertion of index-matching layers on the first and last interfaces. An apodized dielectric mirror and a rugate filter are compared: Appreciable differences in the harmonic presence and stop-band performance were observed and are commented on. Bandwidth control when index contrast is modified is also demonstrated. Finally, the possibility of combining different rugate filter designs to attain more complex responses is demonstrated by the achievement of a multi-stop-band filter. Numerical calculations for design optimization and comparison with experimental data are reported too.
authors.affiliation: Departamento de Física Básica, University of La Laguna, Avenida Astrofísico Fco. Sánchez, E-38204 La Laguna, Tenerife, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Lorenzo
authors.forename: Claudio J
authors.initials: CJ
authors.lastname: Oton
authors.forename: Néstor E
authors.initials: NE
authors.lastname: Capuj
authors.forename: Mher
authors.initials: M
authors.lastname: Ghulinyan
authors.forename: Daniel
authors.initials: D
authors.lastname: Navarro-Urrios
authors.forename: Zeno
authors.initials: Z
authors.lastname: Gaburro
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Pavesi