Non-complementary driving technique for IQ modulator with multi-electrodes to generate high-order optical QAM signals

We propose a configuration for generating high-order quadrature amplitude modulation (QAM) signals using an optical IQ modulator with multi-electrodes of <i>M</i> different lengths. The most notable feature of this configuration is that the four arms in the IQ modulator are driven independently without the use of push-pull drives. Compared to the conventional configuration using classical IQ modulators, the Euclidean distance between symbols in constellation can be increased by 1.2 times, as our technique does not use the push-pull drives that are essential in the classical IQ modulator. Moreover, compared to another conventional configuration that uses a single Mach-Zehnder modulator and multi-electrodes of <i>M</i> different lengths, the proposed configuration requires half the value of <i>M</i> to achieve the same error vector magnitude.