Generation Of The Broadband Chaotic Laser With Erbium-Doped Fiber Ring Laser

With the natural confidentiality, anti-interference, non-predictability, chaos is widely researched in secure communication and anti-interference ranging. The bandwidth of chaos is directly related to the rate of signal transmission and the range resolution. Because the wavelength of the laser produced by erbium-doped fiber laser locates in low loss region, belongs to eye-safe wavelength, and has high average power, it possesses great prospects in the fields of chaotic secure communication and chaotic ranging. Enhancing the chaotic bandwidth of erbium-doped fiber laser and expanding its application in high speed chaotic secure communication and chaotic ranging have become the focus of researchers. The bandwidth of chaos which is produced by nonlinear Kerr effect in erbium-doped fiber ring laser can reach GHz at least. In this paper, focusing on the nonlinear Kerr effect in erbium-doped ring fiber laser,several works are carried out as following:1 We conduct comprehensive review and overview about the research situation and development trend of chaos produced by fiber lasers. We summarize kinds of methods of producing chaos by fiber lasers and analyze each method's advantages and disadvantages.2 The basic principles that erbium-doped fiber laser produces chaos utilizing nonlinear Kerr effect are analyzed, and the nonlinear Kerr effect model is established. We utilize step Fourier method to solve the model.3 We theoretically analyze the process of producing chaos in erbium doped fiber ring laser utilizing nonlinear Kerr effect, and study the influences of pump power and nonlinear coefficient on the bandwidth of chaos. The results show that: under fixed nonlinear coefficient, the bandwidth of the chaos increases first and decreases afterward with the increasing of pump power. Fixing the pump power to 0.1 W, the chaotic bandwidth raises up to 153 GHz when the nonlinear coefficient is enhanced to 45 W-1km-1. Further enhancing the nonlinear coefficient, we can reduce the chaotic bandwidth gradually. We also analyze the reason that the optimal value of bandwidth exists.4 We experimentally study the producing of chaos in erbium doped fiber ring laser by nonlinear Kerr effect, and the process is consistent with numerical simulation. We demonstrate initially that the bandwidth of chaos generated by the model can reach GHz at least.