Optical fiber amplifier and rare-earth element doped multicore optical fiber

Abstract

An optical fiber amplifier includes a first rare-earth element doped optical fiber including a first region including a center of a first core configured to guide signal light, a second region surrounding the first region and doped with a rare-earth element, and a third region surrounding the second region. The optical fiber amplifier includes a second rare-earth element doped optical fiber provided on a signal output-side of the first rare-earth element doped optical fiber, the second rare-earth element doped optical fiber including a fourth region including a center of a second core configured to guide the signal light, and the fourth region being doped with the rare-earth element. The second rare-earth element doped optical fiber includes a fifth region surrounding the fourth region, and includes a sixth region surrounding the fifth region.

Dependencies are inferred from the claim text.