20 February 2024 Numerical analysis and design of polarization-multiplexing modulator utilizing the epsilon-near-zero behavior in ITO-HfO2-graphene stacked layers
Xingxin Fan, Yanhua Shen, Zhiyu Chen, Rongguo Lu, Daolong Shi, Xin Wei, Yong Liu
Author Affiliations +
Abstract

Based on the ITO-HfO2-graphene stacked layers, a modulator that can achieve independent modulation of TE mode and TM mode within a single silicon waveguide is proposed. Graphene and ITO are employed as electrodes of graphene-HfO2-ITO capacitor. Under applied voltage, carriers accumulate within the 5 nm thick ITO film, leading to a modification of the optical dielectric constant. Using ITO’s epsilon-near-zero behavior and its sensitivity to optical polarization, a modulation depth (MD) of no <2.5 dB/μm and an insertion loss of less than 0.054 dB/μm are achieved at the 1.55 μm. Furthermore, when modulating TE and TM modes independently, the mode crosstalk between the two modes is <0.02 dB/μm, demonstrating the high performance of the polarization-multiplexing (PM) modulator. At near-infrared band of 1.35 to 1.6 μm, the broadband properties of ITO and graphene are used to achieve an MD of no <2.2 dB/μm while maintaining mode crosstalk and insertion loss of less than 0.06 dB/μm. This modulator has robustness to top Si waveguide sidewall angle and compatibility with complementary metal oxide semiconductor processes. It is expected to be used in highly integrated polarization de-multiplexing and polarization switching systems.

© 2024 Society of Photo-Optical Instrumentation Engineers (SPIE)
Xingxin Fan, Yanhua Shen, Zhiyu Chen, Rongguo Lu, Daolong Shi, Xin Wei, and Yong Liu "Numerical analysis and design of polarization-multiplexing modulator utilizing the epsilon-near-zero behavior in ITO-HfO2-graphene stacked layers," Optical Engineering 63(2), 027104 (20 February 2024). https://doi.org/10.1117/1.OE.63.2.027104
Received: 21 July 2023; Accepted: 29 January 2024; Published: 20 February 2024
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KEYWORDS
Modulators

Modulation

Waveguides

Graphene

Silicon

Electrodes

Design

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