Optical fiber component, demultiplexer, and optical transmission system

A demultiplexer, comprising:

• an optical fiber component;
• and
• an optical fiber array, wherein
• the optical fiber component comprises:
• a plurality of optical fibers bundled together at one end at least, the plurality of optical fibers including:
• a first optical fiber centered at the one end, and
• a plurality of second optical fibers disposed around the first optical fiber at the one end, wherein each of the plurality of second optical fibers has, at the one end, an output end face having a shape including a straight portion and a corner portion, and
• a filler between the first optical fiber and the plurality of second optical fibers,
• each of the plurality of second optical fibers includes a tapered portion having a cross-sectional area which tapers in a direction from the one end to another end,
• a gap between the first optical fiber and each of the plurality of second optical fibers at the tapered portion is increased from the one end toward the another end,
• an amount of the filler at the tapered portions of the plurality of second optical fibers increases from the one end toward the another end, and
• the optical fiber array comprises:
• a third optical fiber having an input end face with a shape different from that of a further output end face of the first optical fiber at the another end,
• a plurality of fourth optical fibers, and
• a holder configured to hold
• (i) the input end face of the third optical fiber to face the further output end face of the first optical fiber, and
• (ii) a further input end face of each of the plurality of fourth optical fibers to face the output end face of a corresponding second optical fiber of the plurality of second optical fibers at the another end.