Polarization mode dispersion measurement using an improved fixed analyzer method
View Patent ↗A device for performing polarization mode dispersion (PMD) measurements of an optical fiber is disclosed. The PMD measurement device employs a fixed analyzer method, and includes a tunable Fabry-Perot inferometer as the wavelength-selective element and an optical bandpass filter for spectrum calibration. A novel scanning algorithm, which performs multiple scans at different velocities, enables accurate PMD measurements, even of moving optical cable. The tunable Fabry-Perot interferometer is able to scan over a wide wavelength range and yet have a narrow linewidth, such that a wide range of PMD values can be measured.
1. A device adapted to measure polarization mode dispersion of an optical fiber, the device comprising:
an emitter to transmit light through the optical fiber; and
a receiver to analyze the transmitted light, the receiver comprising:
a scanning Fabry-Perot interferometer to perform spectral analysis of the transmitted light; and
a scanning algorithm to control the Fabry-Perot interferometer, wherein the scanning algorithm iteratively scans the Fabry-Perot interferometer at different rates, such that the polarization mode dispersion is accurately measured, even when the optical fiber is moving.
2. The device of claim 1 , wherein the algorithm further:
scans the Fabry-Perot interferometer at a first scan rate to obtain a first dispersion measurement;
scans the Fabry-Perot interferometer at a second rate if the first dispersion measurement is higher than a predetermined amount.
3. The device of claim 1 , further comprising: an optical bandpass filter coupled to the Fabry-Perot interferometer, the optical bandpass filter to filter out undesired interference orders of the Fabry-Perot interferometer, wherein the optical bandpass filter is a calibration reference for the spectral analysis.
4. The device of claim 1 , the receiver further comprising:
a polarizer to polarize the light into a linear polarization state, wherein the receiver analyzes the polarized light.
5. A receiver to analyze light originating from a broadband polarized light source and transmitted via an optical fiber, the receiver comprising:
a scanning filter, comprising:
a scanning Fabry-Perot interferometer to perform spectral analysis of the transmitted light; and
a scanning algorithm to control the Fabry-Perot interferometer, wherein the scanning algorithm:
iteratively scans the Fabry-Perot interferometer at different rates, such that the polarization mode dispersion is accurately measured, even when the optical fiber is moving.
6. The receiver of claim 5 , wherein the scanning algorithm further:
scans the Fabry-Perot interferometer at a first scan rate to obtain a first dispersion measurement;
scans the Fabry-Perot interferometer at a second rate if the first dispersion measurement is higher than a predetermined amount.
7. The receiver of claim 5 , further comprising:
an optical bandpass filter coupled to the Fabry-Perot interferometer, the optical bandpass filter to filter out undesired interference orders of the Fabry-Perot interferometer, wherein the optical bandpass filter serves as a calibration reference for the spectral analysis.
8. The receiver of claim 5 , further comprising:
a polarizer to polarize the light into a linear polarization state, wherein the receiver analyzes the polarized light.
9. The receiver of claim 5 , wherein the broadband polarized light source is a light-emitting diode.