Stability improvement in a gain-clamped L-band erbium-doped fiber amplifier through hybrid gain control

Abstract

The stability of gain-clamped erbium-doped fiber amplifiers (EDFAs) may be affected by the parameter drift of active and passive devices. We propose a hybrid gain-control scheme to enhance the working stability, which consists of an optical dual-fiber-Bragg-grating (FBG)-based linear cavity and an electrical fuzzy-based controller. The principle of optical gain clamping is then depicted and a detailed design about dual-channel fuzzy controller is given. The experimental results show that, in the dual-FBG configuration, with 20.2-dB mean gain, the designed L-band EDFA simultaneously guarantees the ±0.1-dB stability (with 30-dB dynamic range) and the ∼0.4-dB flatness in the range of 1570 to 1610 nm. In addition, under the electrical feedback control, the flatness stability of gain spectrum reaches ±0.18 dB within 60 min and the mean gain stability is about ±0.34 dB within 10-h continuous operation.