Suppression of third-order intermodulation distortion in analog photonic link based on dual-parallel Mach-Zehnder modulators

A linearization scheme for the microwave photonic link based on dual-parallel Mach-Zehnder modulator is proposed, which can suppress the third-order intermodulation distortion (IMD3) introduced by the nonlinearity of the electrooptical modulator and thus improve the spurious-free dynamic range (SFDR). By adjusting the optical power splitter, phase shifter, one of the three main factors that produce IMD3 can superimpose destructively with the other two. Theoretical analysis and simulation results show that our proposed scheme has a better electrical signal-to-interference ratio of 24.9 dB than the conventional scheme, and thus the SFDR has a 9 dB center dot Hz(2/3) improvement. In addition, in the back-to-back system, the error vector magnitude of a 250-MSym/s 16-quadrature-amplitude-modulation is reduced to 2.98% in our proposed scheme compared with the conventional scheme of 14.17%.