Multi-octave linearized RF/photonic link based on orthogonal modulation and optimized demodulation

In this Letter, we propose and demonstrate a multi-octave linearized analog radio-frequency (RF)/photonic link with orthogonal modulation and optimized demodulation. In our proposed link, the DC-reserved (DCR) digital method is utilized in a parallel Mach-Zehnder-modulator scheme to greatly improve the tolerance to the in-phase/quadrature amplitude imbalance and Q-path DC error, which inevitably exist during digital processing. The fault tolerance and transmission performance of the link are theoretically analyzed and experimentally verified. Compared with the traditional digital-signal-processing method, higher signal-to-distortion ratios can be achieved by the DCR method when the amplitude imbalance and DC errors are considered. As a result, the SFDR2 and SFDR3 (spurious-free dynamic ranges) of our system are measured to be 103.74 dB . Hz(1/2) and 116.31 dB . Hz(2/3), respectively. Furthermore, the linearization of the link is demonstrated by testing the RF signals with various frequencies, which proves the potential in broadband applications. (C) 2021 Optica Publishing Group