Pure 2.5 Gb/s 16-QAM signal generation with photonic vector modulator

A novel photonic vector modulator architecture for generating pure quadrature amplitude modulation (QAM) signals is presented. No electrical devices apart from the local oscillator are needed in the generation process. Both binary and multilevel digital signals can be used to generate quadrature phase shift keying (QPSK) or multilevel QAM (M-QAM) digital modulations at any carrier frequency. A pure 2.5Gb/s 16-QAM signal has been experimentally generated at a 42 GHz carrier frequency.