A NEW FILTERLESS W-BAND MILLIMETER WAVE SIGNALS GENERATION SCHEME WITH FREQUENCY OCTUPLING BASED ON CASCADED MACH-ZEHNDER MODULATORS

The existing frequency bands, such as the C-band and L-band, are becoming increasingly crowded and cannot meet the growing demand for high-speed data rate services. To overcome spectrum congestion, meet future business needs, and overcome the bottlenecks of traditional electronic methods, we have modified an approach for generating W-band mm-wave signals with octupling frequency without the need for an optical filter. One integrated modulator consisting of two push-pull Mach-Zehnder modulators (MZM) in series is employed to achieve W-band signal generation. The octupling frequency signal generation depends on +/- 4th optical sidebands to beat frequency in the photodetector. For capturing +/- 4th optical sidebands, the bias point of the two push-pull MZMs needs work at the peak point, and the modulation index of the two MZMs should be simultaneously set to 2.4. We have conducted detailed mathematical derivation and computer simulation for the scheme, demonstrating its correctness. The results show that the optical sideband suppression ratio is not less than 45.73 dB, and the RF sideband suppression ratio can reach 37.64 dB.