IN-LINE ARRANGEMENT FOR MEASURING POLARIZATION EXTINCTION RATIO

摘要

An in-line polarization extinction ratio (PER) monitor that generates a value of an optical signal's PER from a single measurement, without requiring the optical transmission signal path of the system to be directly coupled into a separate measurement device. The polarization extinction ratio may be defined as: 10 log(PEx/PEy), where PEx is the power of the optical signal propagating along the “x axis” and PEy is the power propagating along the orthogonal “y axis” (with the z-axis defined as a longitudinal optical axis of the system and the x-y plane orthogonal to this direction of propagation). The PER monitor comprises a section of optical fiber (preferably birefringent or with induced birefringency), with a pair of gratings formed along the fiber and oriented to out-couple orthogonal components of the propagating signal. Photodetectors are used to convert the scattered light into electrical signal equivalents and then processed to yield the PER value. By properly aligning the axes of the monitor and the optical system, the two measurements are sufficient to provide a one-shot, real-time calculation of the PER of the optical signal propagating through the system.

主权项

1. A device for providing a determination of a polarization extinction ratio of a propagating optical signal, the device comprising:
an optical signal path disposed to receive as an input the propagating optical signal; at least two means for out-coupling portions of the propagating optical signal from the optical signal path; photodetecting means disposed to receive the out-coupled portions of the propagating optical signal from the at least two means for out-coupling signals and convert the out-coupled portions into electrical signal representations of the optical power of the out-coupled portions; and processing means responsive to the electrical signal outputs from the photodetecting means for determining the polarization extinction ratio value using the electrical signal representations.