Linearity optimization of multi-octave analog photonic links based on power weighting, polarization multiplexing and bias control

We present and demonstrate an approach to linearizing analog photonic links (APLs) with substantially enhanced multi-octave spurious-free dynamic range (SFDR). Combining with power weighting, polarization multiplexing and bias control techniques, the proposed approach enables the second-order harmonic distortion (HD2) and third-order intermodulation distortion (IMD3) to be suppressed simultaneously. To maximize the RF output power, an optimization model is established. The simulation results indicate that the maximum RF power can be attained when the power weighting factor and polarization incident angle are equal to 0.5 and 0.34 radians, respectively. The link is validated with a proof-of-principle experiment. The third-order SFDR is 112.3 dB·Hz²/³, corresponding to the improvement of 15.5 dB as compared with a quadrature-biased link. The second-order SFDR reaches as high as 94.6 dB·Hz¹/². Furthermore, the adjacent channel power ratio (ACPR) is measured to be up to 54.6 dBc, which is 5.4 dB greater than that of a quadrature-biased link. Finally, the system tolerances for the RF and optical input power are also investigated in terms of error vector magnitudes (EVMs). Therefore, by introducing optimization model, our scheme provides further insight into the APL linearization technique and a better performance is also achieved.