Patent ID: 8787710

Claim:
A wideband interferometer type polarization beam combiner and splitter, comprising: an optical splitting unit; an optical coupling unit; an optical path length difference imparting unit comprising a plurality of optical waveguides arranged between the optical splitting unit and the optical coupling unit; one or two first input/output ports connected to the optical splitting unit; and two second input/output ports connected to the optical coupling unit; wherein: the optical path length difference imparting unit includes, along the optical waveguides, means for generating differential birefringence and means for generating a difference in refractive index dispersion; and wherein: polarization combining is performed by inputting light in a first polarization state and light entering in a second polarization state at the two second input/output ports connected to the optical coupling unit, and by outputting the light through the one or two first input/output ports connected to the optical splitting unit, or polarization splitting is performed by inputting light at the one or two first input/output ports connected to the optical splitting unit, and by outputting light in the first polarization state and light in the second polarization state, respectively, through the two second input/output ports connected to the optical coupling unit, and wherein: a half-integer of a wavelength of λc is set as a normalized phase difference, for the optical path length difference imparting unit, between the first polarization state and the second polarization state; and wavelength fluctuation of the normalized phase difference is suppressed by a difference in refractive index dispersion that is provided by the means for generating a difference in refractive index dispersion, the wavelength fluctuation having opposite plus and minus signs for the first polarization state and the second polarization state.