Research On Characteristics Of Broadband Parametric Amplifiers

Parametric amplification is one of the well known technologies, and it is rapidly developing with the development of fiber communication. As its characteristics of high gain, wide bandwidth, wavelength conversion, phase sensitivity, and operation at any wavelength, it has attracted the attention of many researchers. The main principle of parametric amplification is the effect of Four Wave Mixing (FWM) which is caused by the nonlinear effect. It can not only amplify the signal, but also bring a new wavelength when the phase-matching condition is matched. The characteristics of FOPA and SOPA with single pump and double pumps are investigated, including gain, bandwidth and Noise Figure (NF). By numerically simulating of FOPA, the reasonable parameters such as pump power, fiber nonlinear index, the wavelength of the pump, zero dispersion wavelength and so on should be properly choosed. Through the analysis of the characteristics of SOPA, we can optimize the parameters including pump power, silicon length, pump repetition rate and free carrier life to achieve the high gain and low noise.For FOPAs based on HNLF, the detrimental effects of ZDWL fluctuation on gain, bandwidth and Noise Figure are investigated. The design of pump spacing should be optimized to balance the conflicting requirement of large bandwidth and low fluctuation of gain and noise. From the analysis, it can be known that it is necessary to increase pump power and the nonlinear coefficient of HNLF in the FOPA. The detrimental effects on NF can be decreased. It is better to choose fiber with low ZDWL fluctuation for obtaining high gain and low noise.For SOPAs, a detailed numerical investigation of the pump to signal RIN transfer is presented. The power and free-carrier lifetime play important roles for RIN transfer in SOPAs. We also analyze the detrimental effects of RIN transfer on noise figure in single-and dual-pump SOPA. It increases the final noise and degrades signal quality amplified by the SOPA. The final noise figure can increase 7dB with the free-carrier lifetime of 0.3 ns in dual-pump SOPA, when the noisy pump laser with-115dB/Hz RIN value. It is evident that it is necessary to decrease RIN value of the pump laser.