A filterless optical millimeter-wave generation based on frequency octupling

A novel method of a filterless optical millimeter-wave (MMW) signal generation with frequency octupling using four nested Mach–Zehnder modulators (MZMs) is proposed for Radio-over-fiber systems. By symmetrically biasing the MZMs and using two RF driving signals with 90 deg phase delay, a cost-effective, high-quality and filterless optical millimeter-wave at 80 GHz with an optical harmonic distortion suppression ratio exceeding 40 dB is obtained. The proposed system is insensitive to the MZM bias drift, which demonstrates a relatively higher stability. So it is a viable solution for the future ultra-high frequency MMW applications.