Silicon photonic modulators rely on the plasma dispersion effect by free-carrier injection or depletion, which can only induce moderate refractive index perturbation. Therefore, the size and energy efficiency of silicon photonic modulators are ultimately limited as they are also subject to the diffraction limit. Here we report an ultracompact electro-optic modulator with total device footprint of 0.6 × 8 μm² by integrating voltage-switched transparent conductive oxide with one-dimensional silicon photonic crystal nanocavity. The active modulation volume is only 0.06 um³, which is less than 2% of the lambda-cubic volume. The device operates in the dual mode of cavity resonance and optical absorption by exploiting the refractive index modulation from both the conductive oxide and the silicon waveguide induced by the applied gate voltage. Such a metal-free, hybrid silicon-conductive oxide nanocavity modulator also demonstrates only 0.5 dB extra optical loss, moderate Q-factor above 1000, and high energy efficiency of 46 fJ/bit. The combined results achieved through the holistic design opened a new route for the development of next generation electro-optic modulators that can be used for future on-chip optical interconnects.

中文翻译：

---

具有0.02立方立方活性体积的超紧凑型硅导电氧化物纳米腔调制器

硅光子调制器依赖于通过自由载流子注入或耗尽而产生的等离子体分散效应，这只能引起中等程度的折射率微扰。因此，硅光子调制器的尺寸和能量效率最终受到限制，因为它们也受到衍射极限的限制。这里，我们报告具有0.6×8μm的总装置占据空间的超小型电-光调制器²通过积分电压交换透明导电氧化物具有一维硅光子晶体纳米。有效调制量仅为0.06 um ³，该值不到lambda-cubic体积的2％。该器件通过利用由施加的栅极电压引起的导电氧化物和硅波导的折射率调制，以腔谐振和光吸收的双重模式工作。这种无金属的杂化硅导电氧化物纳米腔调制器还显示出仅0.5 dB的额外光损耗，高于1000的适度Q因子以及46 fJ / bit的高能效。通过整体设计获得的综合结果为下一代电光调制器的开发开辟了一条新途径，该电光调制器可用于未来的片上光互连。