ELLIPTIC CORE TYPE POLARIZATION PLANE MAINTAINING OPTICAL FIBER AND OPTICAL FIBER POLARIZER

摘要

PURPOSE:To allow the formation of a preform to a large size with high quality by using an elliptic core fiber and setting the structure parameter of the optical fiber at an adequate value. CONSTITUTION:Both side faces of a core rod 3 consisting of a core 1 contg. Ge or GeO2 and a clad 2 contg. F enclosing this core are removed by grounding along the axial direction to form a ground core rod 5 having a noncircular sectional shape. SiO2 glass soot 6 is externally deposited on the outer periphery thereof and this soot is vitrified by sintering to form an SiO2 glass layer as a support 7. The clad 3 is deformed to the clad 8 of a nearly circular section and the core to an elliptic core 9 at the time of this sintering, by which the glass preform is formed. The specific refractive index difference of the core 1 based on the clad 2 is specified to = 1.8%, the ellipticity of the core to =0.8% and the double refractive index of the mode at the use wavelength to =4.5X10-4. The formation of the preform having the high quality to the larger size is possible in this way.