“…Xue used a combination of MZM cascade and polarization multiplexing to solve the power loss problem of optical filters. The optical carrier component can be suppressed by adjusting the angle of polarization controller (PC) and linear polarizer (PoL) [62] . Theoretically, this scheme has the advantages of high frequency multiplication factor, high spectral quality and good transmission performance, but it is difficult to achieve the MZM extinction ratio of at least 70dB.…”