| 摘要 |
PURPOSE:To prepare fixed polarisation fiber capable of obtaining high polarisation maintaining characteristics with high reproducibility by arranging a core glass rod and a stress generating glass rod appropriately in a quartz tube to make the quartz solid and to one body, and then drawing to wire. CONSTITUTION:A core glass rod 13 having a rectangular sectional shape with a core layer 11 having a circular sectional shape in the central part is prepd. by grinding a preform member 10 comprised of a core layer 11 and a clad layer 12. Then, a thermal stress generating glass rod 14 having higher coefft. of thermal expansion than the core glass rod 13 is arranged to the position facing oppositely to each other on both sides of the core layer 11 along a longer side of the rectangular section of the core glass rod 13, and the glass rod is inserted into a quartz tube 15. The inside of the quartz tube 15 is evacuated and solidified and integrated by heating. Obtd. rod is drawn at high temp.; thus, a fixed polarisation fiber 16 comprised of a core 11', clad 12', and a thermal stress generating layer 14' is prepd. Said thermal stress generating layer 14' faces the core 11' with a linear sectional shape 17 forming a structure strong to the shift of the thermal stress generating layer 14' from an axis of symmetry. |
