Research And Application Of Time Lens Based On Four-Wave-Mixing

The time lens can not only realize the compression or stretching of the input signal pulse,but also realize the conversion between the time domain and the frequency domain.It exhibits a powerful function in signal processing.Therefore,time lens has many applications in the fields of ultrashort pulse generation,ultrashort pulse detection,and realtime spectrum analysis,and has great potential for development.There are four main ways to implement time lens,and each implementation method has its own characteristic.This paper focuses on the realization of the time lens based-on the four-wave-mixing(FWM)effect,the various functions of the time lens are simulated,the factors that may cause the result error are analyzed,and the structural performance of the time lens is analyzed.And a certain degree of optimization has been carried out.Finally,the application of time lenses in nonlinear Fourier transform is verified and discussed.The main work done in this paper can be summarized as follows:(1)Based on the principle of Space–Time Duality,the similarities,between the diffraction of spatial monochromatic paraxial light and the dispersion of the narrowband temporal optical pulse,are analyzed and compared.The principle of time lens,the condition and the principle of temporal Fourier transform,the condition and the law of temporal imaging are deduced and analyzed,mathematically.(2)The function of Fourier transform and temporal imaging of time lens based-on FWM is simulated.And the influence of the system structure parameters is also analyzed.(3)Focused on the influence of SPM effect in the Four-Wave-Mixing-based time lens,the cause of SPM non-linear phase shift is deduced,and the compensation method of this non-linear phase shift is verified by simulation.Then,the performance of the time lens is optimized by using the compensation structure of SPM effect.(4)According to the function of time lens for signal compression or stretching,a new application of time lens in non-linear Fourier transform is proposed,which can realize the conversion of temporal waveforms corresponding to different discrete spectral eigenvalues by using the temporal imaging.And it is verified by the simulation.