Simultaneous PMD monitoring of several WDM channels using subcarrier tones

Summary form only given. We demonstrate a simple technique for simultaneous and independent PMD monitoring by adding subcarrier tones at slightly different frequencies to the different WDM channels. Our statistical investigation shows a close correlation between the measured power penalty and the subcarrier power fading of each channel. This technique could be very useful for in-line monitoring of several optical channels without the need for optical demultiplexing and multiple detectors.