title: Flat-top narrow-band spectral response obtained from cascaded resonant grating reflection filters.
abstract: Cascaded identical resonant grating reflection filters are shown to exhibit flattened spectral responses when the individual filter elements are cascaded pi out of phase. Off resonance, the net response of a cascaded arrangement is given approximately by the sum of the individual filter responses. Cascading filters pi out of phase thus result in a reduction in the off-resonance reflection levels and correspondingly an increase in the spectral bandpass ratio. The spectral bandpass ratio is a figure of merit used to gauge the flatness of a response and is defined as the ratio of the linewidth at an efficiency of 90% to the linewidth at an efficiency of 10%. Cascading two and three filters in this manner results in respective increases in the spectral bandpass ratio of three times and more than five times that of a single filter.
authors.affiliation: School of Optics/Center for Research and Education in Optics and Lasers, University of Central Florida, Orlando 32816-2770, USA.
authors.forename: Donald K
authors.initials: DK
authors.lastname: Jacob
authors.forename: Steven C
authors.initials: SC
authors.lastname: Dunn
authors.forename: M G
authors.initials: MG
authors.lastname: Moharam