OPTICAL FILTER MODULE AND OPTICAL AMPLIFIER USING THE SAME

摘要

An optical filter module with isolator function that has no polarization dependent property and in which no polarization mode dispersion occurs. An optical filter is arranged between a first optical input and output terminal and a second optical input and output terminal. A polarization splitting unit is arranged between the first optical input and output terminal and the optical filter, for separating the light into a first straight polarized light and a second straight polarized light which are in parallel to each other and which have polarization states perpendicular to each other. A first polarization rotation unit is arranged between the polarization splitting unit and the optical filter, for rotating the polarization state of the first straight polarized light by 90.degree. and then sending a first rotated light to the optical filter. A second polarization rotation unit is arranged between the optical filter and the second optical input and output terminal, for rotating light passing through the optical filter by 90.degree. and then sending a second rotated light. A polarization combining unit is arranged between the optical filter and the second optical input and output terminal, for combining the first rotated light with the second rotated light and outputting the resultant to the secondinput and output terminal.