| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an optical fiber of non-quartz-based glass in which a fiber loss is low, and which can fusion-bond on a vertical cut face to a quartz fiber, and also can be used as an amplification medium of an L-band optical amplifier practical in a low nonlinearity. <P>SOLUTION: This optical fiber is a fluorophosphate fiber having a double clad at one core and surrounding it, with an added rare earth to at least core glass, when refractive indexes of a core, a first clad and a second clad are n<SB>1</SB>, n<SB>2</SB>and n<SB>3</SB>, a relationship of n<SB>3</SB>≥n<SB>1</SB>>n<SB>2</SB>holds true, and the refractive indexes of a quartz glass-made fiber to be connected, the core, and first clad glass are identical within 0.2% and a yield temperature of glass is equal to or more than 450°C. The outside second clad has a cross-sectional area which occupies 70% or more with respect to a fiber cross-sectional area, and has a composition not containing an alkaline earth. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
