Fiber optic grating with tunable polarization dependent loss

An optical arrangement for providing tuning of the principle states of polarization and polarization dependent loss of an optical signal, the arrangement comprising a cascaded plurality of tunable polarization dependent loss elements, each element comprising

• a section of optical fiber including a highly tilted optical grating formed in the core region thereof;
• a first rotation element disposed to mechanically hold a first end of said section of optical fiber, said first rotation element for imparting a degree of rotation through a first angle θ1 to said first end of said optical fiber section;
• and
• a second rotation element disposed to mechanically hold a second, opposite end of said section of optical fiber, said second rotation element for imparting a degree of rotation through a second angle θ2 to said second, opposite end of said optical fiber section, wherein the direction and degree of rotation associated with said first and second angles θ1 and θ2 are controlled to provide a desired degree of tuning to control polarization dependent loss.

A method of adjusting the polarization dependent loss of an optical signal propagating along an optical fiber, the method comprising the steps of:

• a) providing a section of optical fiber including a highly tilted optical grating formed in the core region thereof;
• b) passing the optical signal through said highly tilted optical grating;
• and
• c) rotating, about the optical axis, a first end of the section of optical fiber through an angle θ1 and a second, opposing end of said section of optical fiber through angle θ2, with the rotations controlled to reduce polarization dependent loss in the optical signal passing through the highly tilted optical grating so as to out-couple a portion of the optical signal passing therethrough;
• and
• d) measuring the out-coupled signal and adjusting the rotations provided in step c) to continue to reduce the polarization dependent loss.