The balance between extinction ratio (ER) and insertion loss (IL) dictates strict trade-off when designing travelling-wave electro-optic modulators. This in turn entails significant compromise in device footprint (L3dB) or energy consumption (E). In this work, we report a nanoscale modulator architecture that alleviates this trade-off while providing dynamic reconfigurability that was previously unattainable. This is achieved with the aide of three mechanisms: (1) Utilization of epsilon-near-zero (ENZ) effect, which maximizes the attainable attenuation that an ultra-thin active material can inflict on an optical mode. (2) Non-resonant coupled-plasmonic structure which supports modes with athermal long-range propagation. (3) Triode-like biasing scheme for flexible manipulation of field symmetry and subsequently waveguide attributes. By electrically inducing indium tin oxide (ITO) to be in a local ENZ state, we show that a Si/ITO/HfO2/Al/HfO2/ITO/Si coupled-plasmonic waveguide can provide amplitude modulation with ER = 4.83 dB/μm, IL = 0.03 dB/μm, L3dB = 622 nm, and E = 14.8 fJ, showing at least an order of magnitude improvement in modulator figure-of-merit and power efficiency compared to other waveguide platforms. Employing different biasing permutations, the same waveguide can then be reconfigured for phase and 4-quadrature-amplitude modulation, with actively device length of only 5.53 μm and 17.78 μm respectively.
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机译:在设计行波电光调制器时,消光比(ER)和插入损耗(IL)之间的平衡决定了严格的权衡。反过来,这会严重影响设备的占位面积(L3dB)或能耗(E)。在这项工作中,我们报告了一种纳米级调制器架构,该架构减轻了这种折衷,同时提供了以前无法实现的动态可重构性。这是通过以下三种机制实现的:(1)利用近零归零(ENZ)效应,该效应最大化了超薄活性材料可能对光学模式造成的可达到的衰减。 (2)非共振耦合等离激元结构,支持非热远距离传播的模式。 (3)类三极管偏置方案,用于灵活地控制场对称和随后的波导属性。通过电感应氧化铟锡(ITO)处于局部ENZ状态,我们表明Si / ITO / HfO2 / Al / HfO2 / ITO / Si耦合等离子体波导可以提供ER = 4.83 dB /μm的振幅调制, IL = 0.03 dB /μm,L3dB = 622 nm,E = 14.8 fJ,与其他波导平台相比,显示调制器的品质因数和功率效率至少提高了一个数量级。利用不同的偏置排列,可将同一波导重新配置为相位和四正交幅度调制,有源器件长度分别仅为5.53μm和17.78μm。
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