| 摘要 |
PURPOSE:To widen the absolute single polarizing wavelength band by making the coefft. of thermal expansion of a stress imparting part larger than the coefft. of thermal expansion of an inside clad and outside clad. CONSTITUTION:The coefft. of thermal expansion of the stress imparting part is made larger than the coefft. of thermal expansion of the inside clad 4 and the outside clad 5 to satisfy the relations n1x<n3x<ncx, n3x<=n2x, n1y<n3y, n3y<=n2y when the refractive indices of the core 1, the inside clad 4, the outside clad 5, and the stress imparting part 6 are designated respectively as ncx, n1x, n2x and n3x with respect to the (x) polarization and ncy, n1y, n2y and n3y with respect to (y) polarization in case of defining the direction where the stress imparting part 6 applies stress as a direction (x) and the direction orthogonal therewith as a direction (y). The high refractive index is, therefore, obtd. by the synergistic effect of the refractive index of the stress imparting part 6 and the stress. The absolute single polarization wavelength band is thereby widened. |
