Optical millimeter-wave generation via frequency octupling circuit based on two parallel dual-parallel polarization modulators

Abstract

In this paper, a filterless optical millimeter-wave (mm-wave) generation by frequency octupling based on two parallel dual-parallel polarization modulators circuit is proposed. From the theoretical analysis, ± 4th order optical sidebands can be generated by proper adjustment of the phases of the radio-frequency (RF) drive signals and polarizer angle. Since there is no need for an optical filter to suppress the optical carrier or unwanted harmonics, the system is suitable for the optical generation of highly stable and tunable mm-waves. Theoretical analysis is verified by computer simulation. From the obtained results, it is shown that the optically generated mm-wave signal from the proposed circuit has a high optical sideband suppression ratio (OSSR) and radio-frequency spurious suppression ratio (RFSSR) for a wide range of modulation index. This range of modulation index extends, theoretically, from 1.8 up to 7.3. For instance, at a modulation index of 5.318, an 80 GHz can be generated from a 10 GHz RF drive signal with an OSSR of 68.4 dB and an RFSSR of 62 dB. Furthermore, the effects of non-ideal system parameters on the OSSR and RFSSR are investigated.