| 摘要 |
PURPOSE:To obtain the titled optical fiber useful for long wave band, by piling the first glass film which will become a jacket layer piled on the inner wall of a quartz tube in such a way that the thickness of the first glass film has a specific calculated value. CONSTITUTION:In a method to prepare the titled fiber by piling the first glass film which will become a jacket layer containing at least boron, having a refractive index approximately equal to that of a quartz tube, on the inner wall of the quartz tube, the second glass film which will become a clad layer harder than the first glass film, and the third glass film which will become a core layer having a higher refractive inder than the second glass film successively, by modified chemical vapor deposition, collapsing the inside with evacuating it to prepare an elliptic jacket type optical fiber reform preserving plane of polarization, followed by spinning it, the first glass film is piled in such a way that the thickness delta of it has a value shown by the formula when the diameter of the quartz tube is Di, the outer diameter of the preform is D, the outer diameter of the optical fiber after spinning is b, the ellipsis ratio of the elliptic jacket is epsilon, the radius of the core is a, a ratio of the clad thickness to the radius of the core is P, and a ratio of the minor axis of the elliptic jacket to the radius of the core is K. |
