50-Gb/s 16 QAM by a quad-parallel Mach-Zehnder modulator

We fabricated a high-speed quad-parallel Mach-Zehnder LiNbO3 modulator. 12.5-Gbaud (50-Gb/s), 16 QAM was demonstrated, where four binary data streams were electro-optically 16-QAM mapped over a single optical carrier by the superposition of two QPSKs.