Abstract

Higher aggregate capacity on optical fibers has increased interest in the control and mitigation of the polarization properties of optical data signals. At data rates of 40 Gbit/s and above, polarization mode dispersion (PMD) mitigation is expected to be critical for proper network performance.¹ PMD compensators that correct for 1^st and higher order PMD have been proposed and demonstrated.² Due to its dynamic nature, PMD compensation requires active feedback, and therefore a PMD monitor is essential. All-optical PMD monitoring methods are attractive because they are not limited by high bit rates, and they may also provide more PMD information, allowing for better PMD compensation algorithms. Monitoring of the signal’s degree of polarization (DOP) has been demonstrated as a PMD measurement technique,³ however this method is applicable to only a single channel, and requires manipulation of the channel polarization at the transmitter to extract additional PMD information.⁴ These limitations could be addressed if a wavelength sensitive polarization measurement were available. A wavelength sensitive polarimeter (WSP) would provide PMD information for multiple channels. Such information could be employed for multichannel PMD compensation,⁵ as well as single channel methods that employ variable differential group delay (DGD) and therefore benefit from a monitor that measures DGD.⁶ We note that optical spectrum analyzers (or optical channel monitors) are already an essential part of most WDM systems, and the addition of polarization sensitivity to a channel monitor represents a natural generalization that enhances optical performance monitoring in systems with polarization sensitive signals.

© 2002 Optical Society of America