Quadruple-frequency optical two-tone signal generation using a DP-QPSK modulator

Abstract

We investigate a novel frequency-quadruple optical two-tone signal generation method using a DP-QPSK modulator, which includes four Mach-Zehnder modulators (MZMs). One MZM is used to generate a basic two-tone signal. The other MZMs are used to compensate unwanted high-order harmonics and carrier components of the generated signal. In the experiment, a two-tone signal was successfully generated, and the power levels of fourth-order harmonics and the carrier were reduced to levels 36.8 dB and 40.3 dB smaller than the required signal, respectively. We also evaluated suppression ratio of the unwanted components against fluctuations of amplitude and bias voltages for the MZMs.