Simplified optical millimeter-wave generation configuration by frequency quadrupling using two cascaded Mach–Zehnder modulators

We propose what we believe to be a novel method to generate optical millimeter-wave signals with frequency quadrupling using two cascaded Mach-Zehnder modulators (MZMs). Both theoretical analysis and experimental demonstration are presented. By symmetrically biasing the MZMs, without any optical filters or electrical devices, a high-quality millimeter wave at 40 GHz with an optical harmonic distortion suppression ratio of more than 25 dB is obtained. Furthermore, it is also proved to be valid that the proposed scheme is insensitive to the MZM bias drift, which demonstrates a relatively higher stability.