Filterless Frequency 32-Tupling Millimeter-Wave Generation Basedon Two Dual-Parallel Mach-Zehnder Modulators Cascaded

Abstract

A novel scheme for filterless frequency 32-tupling millimeter wave (MMW) generation based on two dual-parallel Mach-Zehnder modulators (DPMZMs) cascaded is proposed. When the MZMs are biased on maximum transmission point and the phase difference of the radio frequency (RF) driving voltage between the two MZMs in DPMZM is , the DPMZM can be used as a quadrupler which can generate ±4n-order optical sidebands. When the phase difference of the RF driving voltage between the two DPMZMs is , the two cascaded DPMZMs can be used as an octupler which can generate ±8n-order optical sidebands. After the ±8th-order optical sidebands are suppressed by adjusting the modulation index of MZMs, the center carrier is suppressed by a polarization multiplexing structure, and the ±8n (n＞2) sidebands are ignored because their amplitude are very small, the main optical components remained of the output of the two cascaded DPMZMs are ±16th-order optical sidebands which can generate frequency 32-tupling MMW through beating them in a photodetector. The theoretical analysis and the simulation experiments are carried out for the scheme proposed in this paper, and the optical sideband suppression ratio (OSSR) of ±16th-order optical sidebands signal and the radio frequency spurious suppression ratio (RFSSR) of frequency 32-tupling MMW signal in theory and experiment are 53.7 dB, 53.53 dB and 47.7 dB, 47.33 dB, respectively. The experiment is consistent with the theoretical analysis, this verifies the feasibility of the scheme. The influence on the OSSR and RFSSR of generated signals causing by the extinction ratio of the MZMs, the initial phases, the amplitudes of the RF drive signal, the azimuth of the polarization controller (PC) and the DC bias drift are investigated. The scheme proposed in this paper has the high multiplication factor and high purity, and is very attractive in the application of MMW.

Keywords: Millimeter wave (MMW)Dual-parallel Mach-Zehnder modulation (DPMZM)Optical sidebandFrequency multiplication factor (FMF)Optical sideband suppression ratio (OSSR)Radio frequency spurious suppression ratio (RFSSR)