LOW DIFFERENTIAL MODE GAIN FEW-MODE ERBIUM-DOPED FIBER AMPLIFIER

摘要

A low differential mode gain few-mode erbium-doped fiber amplifier, comprising a coherent pump unit, a signal mode multiplexer, a wavelength division multiplexer, a first optical isolator, a few-mode erbium-doped fiber, a second optical isolator, an optical filter and a signal mode demultiplexer. The coherent pump unit comprises a pump laser, a demultiplexer, a mode converter, a phase controller, and a pump mode multiplexer, wherein the pump laser generates a high power pump optical signal and inputs same into the demultiplexer; the demultiplexer divides the pump optical signal into multiple pump optical signals; the mode converter converts each pump optical signal onto a required pump mode; next the initial phases of multiple pump optical signals transmitted in the same direction are changed, by means of the phase controller; and finally the pump mode multiplexer multiplexes the multiple pump optical signals having different initial phases into one optical fiber, and uses same as an output signal of the coherent pump unit. The low differential mode gain few-mode erbium-doped fiber amplifier uses a pump beat effect to control gain equalization of the amplifier, thereby reducing a differential-mode gain while obtaining a high gain.