High-speed ADC based on photonic time-stretched technology with dispersion-tunable CFBG.

We propose a photonic time-stretched analog-to-digital converter (PTS-ADC) based on dispersion-tunable chirped fiber Bragg grating (CFBG), by demonstrating a economical ADC system with seven different stretch factors. The stretch factors are tunable by changing the dispersion of CFBG, in order to obtain different sampling points. Accordingly, the total sampling rate of the system can be improved. Only a single channel is required to increase the sampling rate and achieve the effect of multi-channel sampling. Finally, seven groups of different stretch factors ranging from 1.882 to 2.206 are obtained, which are equivalent to seven groups of different sampling points. We successfully recover the input radio frequency (RF) signals with frequencies from 2 GHz to 10 GHz. In addition, the sampling points are increased by 14.4 times and the equivalent sampling rate is increased to 288 GSa/s. The proposed scheme is suitable for commercial microwave radar systems, which can obtain a much higher sampling rate at a low cost.