Simulation And Optimization Of Distributed Fiber Raman Amplifiers

Distributed fiber Raman amplifier is currently attracting consideration reach interest due to its capability to turn the transmission fiber into a wide band, distributed gain medium. It has many unique advantages over traditional amplifier.The author has participated in the research works of distributed Raman amplifier which is part of a key project supported by Zhejiang Province. This paper is a brief summary of the author's work.In chapter 1, the history and present status of distributed Raman amplifiers are introduced at first. Then the principle and main components are discussed specially.In chapter 2, the experimental results of back and forward of small signal pump on/off Raman gain spectrum on G652 fiber is furnished. The pumping source is a 1427.2nm Raman laser with tunable output power. The pumped fiber length is 25.2 kilometer. The Raman gain spectra obtained in different conditions are discussed and analyzed. Based on this, the pumping pattern going to be used in our design is decided.Gain coefficient and noise figure are the most important performance parameter of Raman amplifier. A perfect Raman amplifier means high gain coefficient, low noise figure and low the ripple of both gain coefficient and noise figure. In chapter 3, the theoretical model, design idea and principal functions of Optiamplifier 4.0 simulation software provided by Optiwave Corporation, Canada, are introduced. The 50-kilometer distributed Raman amplifier employing different pumping pattern is designed and optimized using this software. The combination of pumping sources is discussed combined the requirements of the project. The noise figure and the principal factors leading to the noise in different pumping pattern are analyzed.The author's contributions in this project for developing the Raman distributed amplifier are as following:The Raman spectra for some kinds fibers are measured and analyzed, and the distributed Raman amplifier is designed and optimized using simulation software. The simulation of gain-flatness and noise figure of the amplifier is furnished. The method of speeding up the design optimization is explored.By making many efforts, we have completed the overall design of the Raman amplifier, and constructed the testing assemble of it. All this work has laid a good foundation to the success of developing the Raman amplifier.