title: Optical directional couplers with variable spacing.
abstract: Optical directional couplers with variable separation are introduced and analyzed. Closed form solutions to the coupled-mode equations with variable coupling coefficient are presented. A procedure for the design of the best geometry of a variety of applications utilizing variable spacing couplers is also presented.
authors.forename: T
authors.initials: T
authors.lastname: Findakly
authors.forename: C L
authors.initials: CL
authors.lastname: Chen