Narrow-bandpass filters with broad rejection band for single-mode waveguides

Fabry-Perot bandpass filters made of mirrors with both high- and low-Deltan (refractive-index modulation) have simultaneously a broad rejection band and a narrow passband. The higher Deltan's are obtained with multilayer mirrors and the lower with Bragg gratings (BG's). Implementation of a sampling calculation technique based on the characteristic matrix formalism used for interference coatings allows for simulation of hybrid filters constructed from multilayer mirrors and BG's. The possible defects of hybrid filters are extensively analyzed. Bandpass filters made purely of both high- and low-Deltan BG's are also simulated. All these filters are useful for wavelength division multiplexing applications. (C) 2001 Optical Society of America OCIS codes: 050.0050, 310.0310.