Electric-field-induced electro-optic sideband generation on the silicon platform

Integrated electro-optic (EO) frequency combs on silicon platforms primarily rely on the carrier dispersion effect due to the lack of intrinsic second-order nonlinearity. However, this approach faces challenges of complex fabrication processes and high waveguide propagation losses. Here, we demonstrate-for the first time, to the best of our knowledge, in a junction-free silicon modulator-the generation and characterization of EO frequency combs with and without DC bias, where the electric-field-induced method enables an EO frequency comb with four sidebands. The EO comb exhibits a waveguide propagation loss below 0.42 dB/cm, representing an order-of-magnitude improvement over conventional carrier-dispersion-based devices. Our work opens a new avenue for the integrated EO frequency comb on the silicon platform.