A New Scheme to Generate Frequency 12-tupling Millimeter Wave Signals Only Based on Cascaded Three MZMs

In the proposed scheme, only three Mach–Zehnder modulators (MZMs) in cascaded mode are employed to generate a frequency 12-tupling millimeter wave (mm-wave) signal. In order to eventually get the frequency 12-tupling mm-wave signal, it is necessary to generate ±6th order harmonics. Therefore, the next work is to generate pure ±6th order optical sidebands to obtain a high-quality frequency 12-tupling signal. First of all, by adjusting the MZM bias voltage at peak point to suppress odd order sidebands; then, by controlling the phase differences to cancel even order sidebands except for the (6n)th order; lastly, by setting the modulation index to eliminate the 0th order optical carrier. Based on the above, the pure ±6th order optical harmonics are obtained. Moreover, the feasibility of the scheme has been demonstrated through a simulation. The optical sideband suppression ratio (OSSR) and radio frequency spurious suppression ratio (RFSSR) of the generated signal are 59.45 dB and 44.44 dB, respectively. In the end, the non-ideal factors that will affect the signal quality are also analyzed.