Design of an Electro-Absorption Modulator Based on Graphene-on-Silicon Slot Waveguide

Abstract

Compact high-performance electro-optic (EO) modulators are key elements for optical communications. An electro-absorption modulator is theoretically designed. Due to the introduction of graphene film over the silicon slot waveguide, the modulation efficiency is strongly improved. The effect of waveguide dimensions, dielectric insulator thickness, and carrier mobility on performances of the proposed EO modulator have been comprehensively investigated. For the 120-μm-long graphene-on-silicon waveguide modulator, the extinction ratio 28 dB and insertion loss 1.28 dB can be obtained at 1550 nm when drive voltage is 1.91 and 0.59 V, respectively. The 3 dB bandwidth of 117 GHz can be obtained at a small power consumption of 212 fJ/bit. The proposed modulator possesses a high figure-of-merit of 20.5. Its benefits of small size, power saving, and process compatible promises possible applications in on-chip signal processing.

Design of a Graphene Modulator Based on a Hybrid Plasmonic Horizontal Slot Waveguide

“…The optical bandwidth of our work is higher than that in Ref. 26. Though not the largest, a moderate f3dB of 330 GHz offers a favorable transmission speed by our design.…”

“…However, due to the nanometer thickness of graphene, how to strengthen the interaction between the optical field and graphene flake is always a challenging task in Wei Chen, Xin Dong, Yan Xu, Yang Gao, Fei Wang, Xiaoqiang Sun, and Daming Zhang are with the State Key Laboratory of Integrated Optoelectronics, graphene modulators [22]. The slot waveguide structure proposed by Almeida et al can significantly enhance the modal field confinement [23], and has been widely adopted in graphene-based EOMs [24][25][26]. A dualfunction modulator based on graphene-on-silicon suspended slot waveguide has been proposed [17].…”

Graphene on Silicon Modulators

“…Adopting optimized contact strategies and engineered design, involving for example tight confinement in slot-waveguide, Graphene modulators can achieve modulation bandwidth above 100 GHz [35]- [37]. The modulator bandwidth may be also enhanced by adopting the use of travelling-wave electrodes, as already demonstrated with Si and III-V modulators [38]- [39].…”

Low-power electro–optic phase modulator based on multilayer cgraphene/silicon nitride waveguide*

“…Therefore, graphene-based silicon-on-insulator (SOI) hybrid integrated waveguide EO modulators have been widely studied. [16][17][18][19][20][21][22][23][24][25][26][27][28] However, due to the surface roughness of silicon stripe, the propagation loss of SOI waveguide is relatively large (about 2 dB/cm to 3 dB/cm). [29] Comparatively, silicon nitride (SiN) waveguides has much lower propagation loss of ∼ 0.1 dB/cm.…”

“…While, graphene induced electro-refraction effect is intrinsically fit for phase modulation. Though electro-refractive phase modulation in graphene has been reported, [17,19,23,26,35,36] the waveguide configuration is still deserved to be investigated for better performance, such as reducing the capacitance and gate voltage, as well as optimizing the bandwidth and power consumption under conservative values.…”