Tunable PDL of twisted-tilted fiber gratings

We fabricated highly tilted fiber gratings and demonstrated that the broad-band polarization-dependent loss (PDL) of the gratings may be tuned by twisting the fiber along the length of the grating. We show that the PDL for a given twist angle can be determined from a simple Jones matrix calculation which can also take into account birefringence on the PDL axis. We combine the twisted-tilted grating with a polarization controller to form a PDL compensator and use it to minimize the polarization-dependent responsivity of a nonlinear silicon avalanche photodiode.