Dynamic range enhancement of photonic sampling based on chirp management in cavity-less optical pulse source

Abstract

An optimization method to improve the spurious free dynamic range (SFDR) of photonic sampling without sacrificing the signal-to-noise and distortion ratio (SINAD) is proposed and experimentally demonstrated. It is realized by managing the chirp in the generated ultrashort optical pulse train by simply changing the group velocity dispersion (GVD) of the dispersion compensation module (DCM) in the cavity-less ultra-short optical pulse source. In the simulation, the SFDRs of the photonic sampling for the input signals in the frequency range of 0.1 GHz to 40.1 GHz are significantly improved with residual linear chirp in the optical pulse train compared with the situation that the chirp is completely compensated. In the experiment, a 10.1 GHz single-tone microwave signal is sampled and the SFDR is improved by 10.95 dB owing to the residual chirp in the optical pulse train. In addition, the SINAD is improved by 2.76 dB even though the power of the fundamental frequency signal is slightly reduced. The proposed scheme can also be applied to photonic sampling ADCs based on other optical pulse sources, which is favorable for alleviating the limitation from the nonlinearity of the electro-optic amplitude modulator.