Dispersion of the phase shift upon reflection of the reflectors is used to narrow the spectral bandwidth of an all-dielectric bandpass filter for wavelength division multiplexing. The bandwidth is altered by the shifting of the order numbers of the spacer layers (of multiple half-wave optical thicknesses).
© 1998 Optical Society of America
(060.1810) Fiber optics and optical communications : Buffers, couplers, routers, switches, and multiplexers
(120.2440) Instrumentation, measurement, and metrology : Filters
(240.0310) Optics at surfaces : Thin films
Philip Baumeister, "Bandpass Filters for Wavelength Division Multiplexing-Modification of the Spectral Bandwidth," Appl. Opt. 37, 6609-6614 (1998)