Optical fiber

Abstract

The present invention provides an optical fiber in which composites constructing its coating are not complicated, so, there is also little constraint in view of production, and, moreover, delamination between a glass optical fiber and a primary layer, and a bubble in the primary layer hardly arise. The optical fiber of the present invention is an optical fiber which has a glass optical fiber which has a core 1, which passes an optical signal, in a center portion, and a cladding 2 surrounding this, a primary protective layer 3 made to coat the glass optical fiber, a secondary protective layer 4 applied on this primary protective layer 3, and a third protective layer 5 applied to an outer periphery of this secondary protective layer 4, wherein glass transition temperature of the primary protective layer 3 is made to be higher than -20°C and 10°C or lower, glass transition temperature of the secondary protective layer 4 is made to be -10°C or less, and the glass transition temperature of the primary protective layer 3 is set higher than that of the secondary protective layer 4.

Description

technical field [0001] The present invention relates to an optical fiber having a highly reliable cladding layer in the aspect of an optical fiber for transmitting optical signals. Background technique [0002] Conventional optical fibers, generally speaking, have such Figure 4 In the structure shown, a glass optical fiber made of silica glass having a core 1 through which an optical signal can pass at the center and a cladding 2 disposed on the outside thereof is covered with a soft main layer 13, and the main layer 13 It is also coated with a hard secondary layer 14. [0003] In general, the main layer 13 uses a UV-curable resin with a Young's modulus of 3 MPa or less, and the sub-layer 14 uses a UV-curable resin with a Young's modulus of 500 MPa or higher. [0004] However, the material properties of a polymer material vary greatly with a glass transition temperature (hereinafter simply referred to as Tg) as a boundary. In particular, efforts have been made for optical...

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Problems solved by technology

[0016] In particular, microbending is very likely to occur when water bubbles occur at the interface between the glass optical fiber and the main layer 13 or near the glass optical fiber.

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