Patent ID: 8005334

Claim:
An optical fiber holding structure, comprising: a cylindrical holder in an optical receptacle for optically coupling optical fiber and an optical device; a ferrule that holds a tip end section of the optical fiber; a holding member that holds a base end section of the ferrule; and a connector casing that holds the holding member, wherein the tip end section of the optical fiber and the ferrule are inserted into the holder and held therewithin; a spacer is provided that fills a gap between the holder and the holding member in a state in which the tip end section of the optical fiber and the ferrule are inserted into the holder; and the spacer is configured by a ring-shaped body that can be mounted on and removed from an outer circumference of the ferrule, and a portion of the connector casing sandwiched between the ring-shaped body and the holding member in a state in which the tip end section of the optical fiber and the ferrule are inserted into the holder and the ring-shaped body is mounted on the ferrule.