Silicon-integrated optical modulators: surpassing the limitations of plasma-dispersion effect (Invited Paper)

Silicon (Si) photonics stands as a solid candidate to address the scaling challenges of emerging communication systems with an ever-growing number of interconnected devices. However, Si has major physical limitations that prevent on-chip integration of key functions including strong two-photon absorption limiting nonlinear optical phenomenon, an indirect bandgap nature hindering light emission and amplification and more specifically Si is a centrosymmetry semiconductor preventing ultra-fast and low power consumption optical modulation based on Pockels effect. The latter limitation strongly limits the evolution of the photonic integrated circuits (PIC). In this paper, an overview of the different approaches for light modulation in silicon will be presented including the plasma-dispersion effect, currently used in PIC and the Pockels based modulators integrated in Si circuits.