Gain Control Edfa Study

The invention of Erbium-Doped Fiber Amplifier (EDFA) brought an evolution in optical communication. With the advantages of high gain and output power, low noise, wide bandwidth as well as no relation with polarization, EDFA changes the traditional optical-electrical-optical relay mode step by step in many fields, and becomes an indispensable device in modern optical communication systems. It saves the expensive cost in optical-electrical transition, makes equipment easy to operate and maintain. With the updating of WDM system and development of optical transition network, Gain-Clamped Erbium-Doped Fiber Amplifier (GC-EDFA) fixes the problem of gain fluctuation and vibrating when input power and upload channel numbers are changing.Based on the above background and under the support of Tianjin Natural Science Foundation project: Intelligent fiber amplifiers and light sources, Tianjin Natural Science Foundation project: (C+L) broadband fiber amplifier and Nankai-Delta (Tianjin) project: Development of gain flattened erbium-doped fiber amplifiers, this dissertation is mainly focused on the study of novel GC-EDFA, gain and NF (noise figure) improvement of EDFA, light sources, multi-wavelength fiber laser and VOA (Variable Optical Attenuator). The following innovations are mainly covered:1. A novel GC-EDFA based on Hi-Bi (high birefringence) fiber grating is designed. By tuning polarization controller, single and dual control lasers can be obtained as will. Signal and controlling lasers transmit reversely. The average gain and NF are 22.22dB and 8.69dB respectively. Gain flatness under single and double lasers control are 0.69dB and 1.51dB. A gain-clamped dual-stage L-band EDFA by utilizing backward C-band ASE as control light is presented for the first time. The input signal power can be varied within 27dB. 3dB band width reaches 34.5dB. The average gain and flatness are 23.68dB and±0.8dB respectively, with NF of 7.47. We tried different GC-EDFA structures in order to get an optimized device.2. A NF improved EDFA based on Hi-Bi fiber loop mirror as ASE rejecter is proposed. The double-pass amplifier reduces the average NF in 1580.84nm~1588.48nm by 3.7dB. A gain and NF improved double-pass EDFA with a pre-stage amplifier is presented. Compared with that of the conventional one, the gain of L-band EDFA with pre-stage amplifier is 2.3dB~12.6dB higher while NF is 2.2dB~23.9dB lower in the wavelength range of 1568nm~1594nm.