title: 2-LP mode few-mode fiber amplifier employing ring-core erbium-doped fiber.
abstract: A fiber amplifier supporting 2 LP modes that employs a ring-core erbium-doped fiber (RC-EDF) is investigated to reduce differential modal gain (DMG). The inner and outer radii of the ring-core of the RC-EDF are clarified for 2-LP mode operation of the amplifier, and are optimized to reduce the DMG. It is shown that using the overlap integral between the erbium-doped core area and the signal power mode distribution is a good way to optimize the inner and outer radii of the ring-core of the RC-EDF and thus minimize the DMG. A fabricated RC-EDF and a constructed 2-LP mode EDFA are described and a small DMG of around 1 dB is realized for LP01, LP11 and LP21 pumping.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Ono
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Hosokawa
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ichii
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Matsuo
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Nasu
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamada