Broadband Optical Reflection Modulator in Indium-Tin-Oxide-Filled Hybrid Plasmonic Waveguide with High Modulation Depth
A surface plasmon resonance (SPR)-based optical reflection modulator consisting of vertically stacked silica-silicon-HfO2-ITO-HfO2-Ag-prism multilayer is proposed and numerically investigated. The free carrier-concentration-dependent permittivity of indium-tin-oxide (ITO) at the HfO2/ITO interface induces an epsilon-near-zero (ENZ) effect contributing to strong field enhancement and modifies the SPR condition of incident light. With optimal geometry parameters and proper design of carrier concentration at the accumulation layer, modulation depth (MD) of ~100% and insertion loss (IL) of 3.7% can be simultaneously achieved. The IL can be further reduced by engineering silicon layer thickness. Moreover, the device offers a broadband operation wavelength from 1.5 to 1.6 μm with the variations of MD and IL smaller than 4 and 3%, respectively.
KeywordsIntegrated optics devices Surface-plasmon resonance Modulators
This work was partially supported by the National Natural Science Foundation of China (61605179), the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (162301132703, G1323511665), and the 863 High Technology Plan (2015AA015502).
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