Patent ID: 7289728

Claim:
An optical transmission system comprising: a primary path disposed between a first end and a second end, said primary path configured to transmit optical signals between said first end and said second end; a secondary path disposed between said first end and said second end, said secondary path configured to transmit optical signals between said first end and said second end; a first variable ratio coupler coupled to said primary path and said secondary path between said first end and said second end, said first variable ratio coupler configured to adjust a coupling ratio between said primary path and said secondary path; and a second variable ratio coupler coupled to said primary path and said secondary path between said first end and said second end opposite said first variable ratio coupler, wherein said second variable ratio coupler comprises: a second primary detector coupled to said primary path and a second secondary detector coupled to said secondary path, and a primary switch element coupled to said primary path and a secondary switch element coupled to said secondary path.