Multi-pass optical filter

US6055347A · kind A · utility

Inventors

• Jinghui Li · Ottawa, CA
• Neil Teitelbaum · Ottawa, CA

Key dates

• Filing date: Aug 26, 1997
• Grant date: Apr 25, 2000
• Expiry date: Aug 26, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B6/2938
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An optical filter is provided having first and second graded index (GRIN) lenses preferably disposed in a coaxial relationship so that they have a common optical axis. Each of the GRIN lenses has an end face providing a port at predetermined location. The ports are disposed on opposite sides of the optical axis and each of the ports is substantially equidistant from the optical axis, so as to be oppositely offset from the optical axis by a same amount. The filter also includes an optical interference filter disposed between other end faces of the first and second graded index lenses. By providing at least four spaced ports, equidistant from the optical axis, such that two ports form a first couplet on opposite sides of the axis from each other and such that two other ports form a second couplet on opposite sides of the axis from each other, wherein one of the ports of one couplet is optically coupled with one of the ports from the other couplet, an add and drop circuit may be realized. The notion of multi-use of an optical filter applies not only to an add and drop circuit, but also other WDM devices which use several optical filters of a same type.