Polarization-insensitive multi-wavelength switching based on polarization-selective long-period fiber gratings

Novel multi-wavelength switching filters based on cascaded long-period fiber gratings and polarization-maintaining fiber in a Sagnac loop configuration are proposed and experimentally demonstrated. The rapid wavelength switching is achieved by an electro-optic polarization controller. The device is independent of the polarization state of the input light due to the bi-directional polarization compensation of the Sagnac loop interferometer although the polarization state of the optical wave filter is rapidly switched by the electro-optic modulator in the loop. The proposed device can be useful for applications to all-channel gating and odd/even-channel switching devices with fine channel selectivity and high-speed response.