Doubled frequency optical two-tone generation using electro-optic modulator and suppression of redundant spectrum components

Doubled frequency optical two-tone was generated by the dual electrode type electro-optic (EO) modulator with a single Mach-Zehnder (MZ) interferometer. Redundant optical spectrum components of the two-tone waves, which are caused by the imbalance of light splitting ratio in the interferometer, are significantly suppressed by controlling the input power ratio of RF signals applied to each electrode. This effect was confirmed by the experiment, where an optical two-tone with the redundant components 49.8 dB lower than the primary two-tone component level was obtained. This method is also valid for suppression of undesired frequency components of RF signals which are generated by the optical two-tone waves propagated through a dispersive optical fiber.