Optical filter having multiple interferometric stages

US5309534A · kind A · utility

Assignee

• AT&T Bell Laboratories · US

Inventors

• Leonard G. Cohen · Matawan, US
• Charles H. Henry · Skillman, US
• Rudolf F. Kazarinov · Bound Brook, US
• Mark E. Kuznetsov · Lexington, US

Key dates

• Filing date: Feb 24, 1993
• Grant date: May 3, 1994
• Expiry date: Feb 24, 2013

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B6/29355
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

We describe an interferometric, channel-dropping, optical filter that includes a pair of planar waveguides. The two waveguides are spaced apart by a distance which is periodically varied along the longitudinal axis of the filter in order to effect a periodic optical coupling between them. There are at least three coupling locations, each associated with a coupling constant. The two waveguides have nominally equal effective refractive indices. In preferred embodiments of the invention, the coupling constants decrease symmetrically from the center of the filter toward the ends.