All-optical modulation in chains of silicon nanoantennas

Dielectric nanoantennas represent a new branch of nanophotonics allowing efficient control of light scattering at nanoscale. Coupled nanoantennas can guide light on chip over large distances without radiation losses enabling a new nanoantenna-based silicon photonics platform with enchanced functionalities for light-on-chip integration. Here, an all-optical on-chip modulator based on a one-dimensional chain of silicon nanoantennas is proposed and experimentally demonstrated in the 1.55 µm telecommunication wavelength range. A resonator, with a quality factor up to 10000, is designed based on a chain of coupled silicon nanoantennas, each supporting the electric dipole Mie resonance. Wafer level fabrication of the nanoantennas is realized using CMOS compatible photolithography. High-speed modulation of the cavity mode is experimentally demonstrated via optical injection of free electrons and holes using a pulsed laser. The modulator is shown to have a response time of 50 ps and modulation depth beyond 25 dB,...