Time-sensitive And Phase-sensitive Characteristics Of Light-acoustic Parametric Amplifier

With the rapid development of optical fiber communication systems,the EDFA and Raman amplification techniques have not satisfied the requirements of amplification capability of amplifiers.Because fiber optical parametric amplifier(FOPA)based on three-order nonlinearity four-wave mixing(FWM)is difficult to be integrated with silicon-based photonic devices requires to introduce additional pump light source,it increases the system costs.To solve the problems above,we propose the light-acoustic parametric amplifier to realize optical signal amplification based on stimulated Brillouin amplification(SBA)technique.And the theoretical analysis and experimental verification of the time-sensitive and phase-sensitive characteristics have been given in this paper.The amplifier has some possible applications such as Radio over Fiber communication system,narrow-band digital/analog communication,optical clocks and coherent optical detection applications for the abilities of time domain waveform fidelity and frequency domain phase selective.Firstly,based on the theory of Brillouin parametric amplification for the case of anti-Stokes light loss,using the rectangular pulse as pump light,this paper is the first to verify the optical precursor wave phenomenon through the SBA process,which can act as one representation of the waveform distortion.Experimental results are in good agreement with theoretical ones.Based on Brillouin parametric amplification model,the simulation of half-Gaussian pulse and Gaussian pulse time sensitive characteristic under anti-Stokes light loss and Stokes light gain conditions have been studied.In the simulation results of narrow-band pump light light-acoustic parametric amplification for various gains,with the improvement of gains,the pulse waveform begins to distort and the precursor appears.In the simulation results of light-acoustic parametric amplification for different pump linewidths,with the increase of linewidths,the pulse distortion has been corrected.The simulation results are experimentally verified by using half-Gaussian – Gaussian pulse.Optical signal amplification without distortion is achieved using broaden-spectrum pump lightlight-acoustic parametric amplifier.Secondly,this paper introduces the concept and modulation method of Quadrature amplitude modulation(QAM)signal,puts forward the vector signal error analysis method.And then,an experimental setup of QAM signal amplification by light-acoustic amplifier is built.The QAM signal amplification with distortion and without distortion has lower phase noise than EDFA at the same gain.Moreover,the QAM signal with distortion also can be corrected by the narrow-band Brillouin phase selective amplification process.In addition,the influence of pump power and SBA phase matching condition of light-acoustic amplifier on distortion QAM signal correction has also been studied.The experiment results show that the light-acoustic parametric amplifier can realize the distortion QAM signal correction under the conditions of lower than SBS threshold and meeting the SBA phase matching.