▎ 摘　　要

The hybrid plasmonic effect with lower loss and comparable light confinement than surface plasmon polariton opens new avenues for strengthening light-matter interactions with low loss. Here, we propose and numerically analyze a graphene-based electro-absorption modulator (EAM) with high-modulation efficiency and broad optical bandwidth using a dual-slot hybrid plasmonic waveguide (HPW), which consists of a central dual-slot HPW connected with two taper transitions and two additional dual-slot HPWs for coupling it with the input and output silicon nanowires, where graphene layers are located at the bottom and top side of the whole dual-slot HPW region. By combining the huge light enhancement effect of the dual-slot HPW and graphene's tunable conductivity, we obtain a high-modulation efficiency (ME) of 1.76 dB/mu m for the graphene-based dual-slot HPW (higher ME of 2.19 dB/mu m can also be obtained). Based upon this promising result, we further design a graphene-based hybrid plasmonic EAM, achieving a modulation depth (MD) of 15.95 dB and insertion loss of 1.89 dB @1.55 mu m, respectively, in a total length of only 10 mu m, where its bandwidth can reach over 500 nm for keeping MD > 15 dB; MD can also be improved by slightly increasing the device length or shrinking the waveguide thickness, showing strong advantages for applying it into on-chip high-performance silicon modulators. (C) 2018 Optical Society of America