Time-frequency analysis system based on temporal Fourier transform

We propose a new scheme to physically realize the short time Fourier transform of chirped optical pulses using time lens array that enables us to get time-frequency distribution without using FFT algorithm. The idea of Short-time Fourier transform (STFT) is physically realized in our scheme. The Fourier processor based upon a four-wave mixing time lens is used to perform the process of Fourier transformation. The ultra-short optical input signal is divided to multiple duplicates that is delayed in turn, and different short period of time of multiple duplicates are separately transformed into the frequency domain by multiple time lens. Pump pulse is both worked as the provider who has the quadratic phase and the window function of STFT. Simulations have been done to investigate performance of the time-frequency scheme compared with STFT using FFT algorithm.