Programmable DGD Line
This high-speed variable differential group delay (DGD) line provides a variable amount of group delay difference between two linear orthogonal polarization states. DGD is a key component for PMD emulation and compensation. ProDelayT can digitally vary the amount of 1st order PMD from -45 ps to 45 ps with a resolution of 1.36 ps (6-bit resolution) in less than 250 µs. With an integrated circuit board and a software package, the device can easily be controlled with a computer or a microprocessor. The circuit board has a 10-pin TTL digital I/O port to interface with any digital control signal, either from a control circuit board or a computer. An optional Labview PMD emulation software can also available to generate Maxwellian DGD distribution of any average value. In addition to PMD compensation and emulation, this patented device can be used for precision TDM bit alignment.