CONNECTING METHOD OF WAVEGUIDE TYPE OPTICAL ELEMENT AND OPTICAL FIBER FOR RETAINING PLANE OF POLARIZATION

摘要

PURPOSE:To provide a simple connecting method between a waveguide type optical element and incident and exit optical fibers for retaining plane of polarization thereof by interposing single mode fibers which are looped so as to be given optical anisotropy in a specified axial direction between the waveguide type optical element and the optical fibers for retainng plane of polarization. CONSTITUTION:When the light wave of either mode of TM or TE is made incident to optical fibers 1 for retaining plane of polarization, a small loop is formed in the main fiber axis direction of the fibers in each single mode fiber used for a single mode fiber array 3 and therefore either mode of TM or TE is maintained when the light wave arrives at the incident end face of a 4X4 waveguide type optical switch 12, whreby switching is accomplished with good efficiency. The change in a polarization direction owing to an exit single mode optical fiber array 9 and exit optical fibers 11 for retaining plane of polarization does not arise and therefore the light wave is emitted in the polarization direction of the incident light.