Patent ID: 7227686

Claim:
A device, comprising: a plurality of variable DGD (differential group delay) sections cascaded in series to form an optical path, each variable DGD section operable to produce a variable differential group delay and configured to comprise: a plurality of cascaded birefringent segments of different lengths, and a plurality of tunable polarization elements each coupled between two adjacent birefringent segments to control polarization of light; a plurality of polarization controllers each coupled between two adjacent variable DGD sections to control polarization of light transmitting therethrough; and a control unit coupled to said variable DGD sections to apply DGD control signals to respectively control DGD values of said variable DGD sections and coupled to said polarization controllers to apply polarization controller signals to control polarization coupling between two adjacent DGD sections to produce a polarization-mode dispersion profile in light transmitting through said optical path.