Optical transmission systems of the present invention includes at least one double pass Mach Zehnder filter, which includes a first optical coupling section coupling at least one input/output port to a first end of two or more optical communication paths, or Mach-Zehnder legs, having different effective...http://www.google.ca/patents/US20030031404?utm_source=gb-gplus-sharePatent US20030031404 - Optical transmission systems including optical components and optical filters and methods of use therein
