Modulation-dependent limits to intensity-noise suppression in microwave-photonic links

Cancellation of common-mode intensity noise in microwave-photonic links is found to be limited by the applied intensity modulation. A model is developed and verified experimentally for the dependence of the maximum noise suppression on modulation index, for two-tone and multichannel modulation. For example, for a root-mean-square modulation index of 0.3, suppression is limited to 5 dB.