Relationship between the difference of the two arms and spectral width of a dispersion-compensated polarization Sagnac interferometer

The difference of the two arms of a dispersion-compensated polarization Sagnac interferometer (DCPSI) may introduce additional shear distance in the shear distance generated by the equiangular DCPSI that will reduce the spectral width of DCPSI. The effects of interference fringes produced by DCPSI under different wavelengths were analyzed according to the relationship between fringe contrast and the period of interference fringes. The relationship of the difference of the two arms of the DCPSI and the width of the wavelength is presented. Under the condition that the DCPSI can generate interference patterns, this relationship only depends on the difference of the two arms but not the length of the arm. For our experimental structure, we have established the difference of the two arms that should be less than 60 μm and within the 400-700 nm range. This finding is consistent with the calculation results.