Research On Gain-clamped And Broadband EDFA

The emergence of erbium-doped fiber amplifier is the landmark in the history of optical fiber communication. By utilizing EDFAs, all-optical relay is realized, transmission distance is much lengthened, and the development of WDM/DWDM (Wavelength-Division Multiplexing/Dense WDM) communication systems is generally accelerated. Meanwhile, with the development of WDM/DWDM communication systems, more and more attention is paid on the EDFAs with broader bandwidth, good gain and noise feature, and gain clamping, etc.According to the Tianjin Natural Science Foundation project: Intelligent fiber amplifiers and light sources, the Tianjin Natural Science Foundation project: (C+L) broadband fiber amplifier and the Nankai-Delta (Tianjin) project: Development of gain flattened erbium-doped fiber amplifiers, this dissertation is mainly focused on the study of novel gain-clamped EDFA, light sources, multi-wavelength fiber laser and variable optical attenuator for gain-clamped usage, gain and noise improvement of EDFA, and broadband EDFA. The main contents are listed as follows:1. A noise figure improved L-band EDFA based on Hi-Bi (high birefringence) fiber loop mirror as ASE rejecter is presented for the first time. By utilizing the comb-like reflection spectrum of a Hi-Bi fiber loop mirror to suppress the ASE (amplified spontaneous emission) of a double-pass EDFA, the noise figure of this amplifier is much improved. The average noise figure of the double-pass L-band EDFA based on Hi-Bi fiber loop mirror is 3.7dB lower than that of the one based on a common fiber loop mirror.2. A multi-wavelength erbium-doped fiber laser based on fiber polarizer and Hi-Bi fiber loop mirror is put forward for the first time. By utilizing Hi-Bi fiber loop mirror and fiber polarizer to control the intracavity polarization state, a multi-wavelength erbium-doped fiber laser by exploiting PHB (polarization hole-burning) is realized. We have experimentally achieved four-wavelength or five-wavelength stable lasers with wavelength spacing of less than 2nm. Moreover, by using fiber polarizer and birefringence fiber to constitute a Lyot filter, the intracavity PHB effect is enhanced and a dual-wavelength linear cavity erbium-doped fiber laser is achieved. We have experimentally obtained two series of L-band dual-wavelength lasers with wavelength spacing of 3.44nm and 1.56nm, respectively. Furthermore, by tuning the polarization controller, five single-wavelength lasers ranging from 1599.28nm to 1605.84nm can be also acquired.