Yafo Networks Sets Yardstick for Speed of PMD Compensator

HANOVER, Md., July 13 -- Yafo Networks announced that it has measured the tracking speed of the Yafo10 at 500 Hertz (Hz). The test results show that the Yafo10 can compensate for polarization mode dispersion (PMD) even when the state of polarization is changing at a rate of 500 Hz, equivalent to polarization changes every two milliseconds. The Yafo10 will enable 10 Gb/s networks to perform well even in the most challenging environments where PMD experiences rapid changes, such as networks with aerial fiber or fiber laid under railway track that is subjected to vibrations from trains.
PMD is a dynamic phenomenon, which can change rapidly in response to vibration, changes in air temperature, stress, pressure and other external forces. Moderate to high PMD levels can cause 10 Gb/s optical networks to experience errors or outages, which can be difficult to trace because PMD levels can drop back to normal by the time fault detection is carried out.
The tests, carried out at Yafo's labs, included corrupting a 10 Gb/s signal with differential group delay and changes in the state of polarization. Test results showed that bit error rates of the Yafo10 remained unchanged for large changes in polarization (equivalent to 45 degrees rotation in linear polarization) at a frequency of 500 Hz. For smaller polarization changes, even higher tracking speeds were achieved.