Abstract

The optical thickness of discrete, homogeneous, thin film layers in a quarterwave stack can be modulated according to the recently developed layer modulation theory (LMT)¹. Unlike rugate filters with modulated refractive index and suppressed high order stopbands, LMT structures produce harmonic and non-harmonic stopbands of quarterwave stacks. The adjustable frequency spacing of two (or more) stopbands using LMT structures can be predicted from analytical These LMT structures can be used instead of multiple quarterwave stacks, and are not constrained to the spacing of harmonic stopbands from first or higher order quarterwave stacks.

© 1998 Optical Society of America