Monolithic silicon-based 16-QAM modulator using two plasmonic phase shifters

We propose a compact silicon-based modulator for 16-point quadrature amplitude modulation (16-QAM) with a simple structure using two phase shifters. The phase shifters employ low-loss hybrid plasmon waveguide, consisting of a conductor-gap-dielectric structure filled with polymer. Combining the strong optical confinement ability of the plasmonic waveguide with the highly nonlinear characteristic of the polymer, the proposed 16-QAM modulator can achieve a compact footprint, high-speed operation, and low power consumption, potentially allowing for high-density on-chip integration and broadband long-haul optical transmission.