Spectral polarization-dependent loss of cascaded long-period fiber gratings.

We have measured the spectral polarization-dependent losses of cascaded long-period fiber gratings composed of single, double, and triple identical gratings and fabricated by exposure of a UV laser beam on one side of a fiber. The measurement was made by use of the Mueller matrix method for scanning the wavelength of the incident beam. The polarization-dependent loss was dramatically increased as the number of cascaded gratings was increased.