Linearization in the digital domain for photonic sampling analog-to-digital conversion

A linearization scheme in the digital domain for photonic sampling analog-to-digital converter (PS-ADC) is proposed and experimentally demonstrated, where a single-output Mach-Zehnder modulator (MZM) is used for photonic sampling instead of a dual-output MZM (DOMZM) in the traditional schemes. After frequency response calibration of the sampled signal in the digital domain, the optimal direct current (DC) component and the coefficient of sine function are found, and arcsine algorithm is performed to implement the linearization of PS-ADC. The theoretical results indicate that, compared with the differential and arcsine operation method generally employed in PS-ADC, the proposed scheme is facile to implement and decreases the system overhead. The feasibility of the scheme is verified by simulation and experiment. In the proof-of-concept experiment, for a single-tone microwave signal at 100 MHz with a modulation index of 0.45 pi, the second-order harmonic is suppressed below the noise floor, the third-order harmonic suppression ratio is enhanced by 17.14 dB, and the significant improvement in SINAD is equal to 7.91 dB.