GAIN EQUALIZER, LIGHT AMPLIFIER AND OPTICAL COMMUNICATION SYSTEM

摘要

A fiber amplifier uses an erbium-doped fiber core (1) in which a plurality o f long-period fiber gratings (21) functioning as a gain equalizer are formed b y an ultraviolet laser. Each of the fiber gratings (21) is irradiated with ultraviolet laser through the cladding layer of the optical fiber core (1) t o provide periodic modulation for the refractive index of the fiber core. The fiber gratings (21) in the core (1) compensate for the wavelength dependency of gain to provide flat gain, resulting in uniform and efficient amplificati on over a wide range.