| 摘要 |
PURPOSE:A glass rod consisting of a round core and a not round clad is inserted into a specific quartz tube, integrated by heat melting, then drawn into a filament to enable inexpensive production of a constantly polarized filament of good polarization properties and low loss. CONSTITUTION:A glass rod consisting of core 11 and clad 12 is made by a known method. At this time, the core 11 is set in refractive index higher than the clad 12. The resultant glass rod is abraded or cut into a not round cross section other than oval form. A quartz tube 15 is coated with an accumulated stress developer 14 which has a different thermal expansion coefficient from the clad 12 on its inside, the above glass rode is inserted thereinto and they are integrated by melting with heat and drawn into a filament. Since thermal stress anisotropy which decides birefringence is controlled by the shape of the abraded rod, further the abrasion can be done with high precision easily, good maintenance of constant polarization can be performed with high reproducibility. |
