Signal Frequency Chirp of Photonic Time-Stretch System Due to Nonlinear Dispersion

In this letter, signal frequency chirp due to nonlinear dispersion in a photonic time-stretch system is analyzed, and a correction method is proposed and experimentally demonstrated. A time-dependent frequency transfer function is derived for the first time, which can be taken as an instruction for the correction of signal frequency chirp in a digital domain. The numerical simulation shows the proposed correction method applicable to both the single-tone signal and broadband signal transmissions. The experimental result proves that the demodulated signal quality of a transmitted QPSK signal is significantly improved after the correction of signal frequency chirp in the digital domain.