Broadband and High-Capacity Silicon Photonics Single-Sideband Modulator

We propose a novel photonic-integrated single-sideband (SSB) modulator realized in silicon on insulator technology operating either in suppressed-carrier or full-carrier mode with continuously tunable carrier-to-sideband ratio (CSBR). Large rejection levels of the spurious sidebands and residual carrier in excess of 40 and 30 dB, respectively, with a CSBR tunability over a $\sim$ 50 dB range, are demonstrated. By employing a single silicon photonics (SiP) phase modulator and a compact and high-performance filtering element, the proposed architecture exhibits a compact layout and tolerates high driving voltage levels, leading to large OSNR values of the modulated sideband in excess of 50 dB. The device supports broadband RF data signals and its operation is tested with an up to 5 Gbps ASK-modulated carrier at 16.5 GHz, limited by available RF equipment. Furthermore, the technique allows to implement a frequency-multiplication mechanism for the input RF carrier, and up to threefold effective bandwidth enhancement of the SiP modulator is obtained by generating an optical SSB signal with a modulated spectral component spaced by 49.5 GHz from the optical carrier. Such features are promising for implementing cost-effective optical distribution of millimeter-wave wireless data signals supporting the evolution of next-generation radio access networks.