Patent ID: 7315699

Claim:
An optical device for extracting first and second optical streams of data from an optical signal at a wavelength λ c wherein the data streams are separated by a predetermined wavelength difference δλ, the device comprising: an input polarization beam splitter having both an input port for receiving said optical signal and at least one output port defined by a predetermined polarization state; a polarization maintaining fiber having a primary polarization axis, the fiber being coupled to both the at least one output port of the input polarization beam splitter at a predetermined angle to the primary polarization axis and an input port of an output polarization beam splitter at a second angle to the primary polarization axis, the second angle being related to the predetermined angle, the fiber being characterized by a beat length L beat , wherein the fiber has a length substantially equal to (L beat ×λ c )/2δλ; and the output polarization beam splitter having both said input port and first and second output ports defined by substantially orthogonal polarization states, the first and second optical data streams output from the first and second output ports, respectively, of the output polarization beam splitter.