Amin Rubab, Maiti Rishi, Gui Yaliang, Suer Can, Miscuglio Mario, Heidari Elham, Khurgin Jacob B, Chen Ray T, Dalir Hamed, Sorger Volker J
Department of Electrical and Computer Engineering, George Washington University, Washington, DC, 20052, USA.
Electrical and Computer Engineering Department, Microelectronics Research Center, University of Texas at Austin, Austin, TX, 78758, USA.
Sci Rep. 2021 Jan 14;11(1):1287. doi: 10.1038/s41598-020-80381-3.
Densely integrated active photonics is key for next generation on-chip networks for addressing both footprint and energy budget concerns. However, the weak light-matter interaction in traditional active Silicon optoelectronics mandates rather sizable device lengths. The ideal active material choice should avail high index modulation while being easily integrated into Silicon photonics platforms. Indium tin oxide (ITO) offers such functionalities and has shown promising modulation capacity recently. Interestingly, the nanometer-thin unity-strong index modulation of ITO synergistically combines the high group-index in hybrid plasmonic with nanoscale optical modes. Following this design paradigm, here, we demonstrate a spectrally broadband, GHz-fast Mach-Zehnder interferometric modulator, exhibiting a high efficiency signified by a miniscule VL of 95 V μm, deploying a one-micrometer compact electrostatically tunable plasmonic phase-shifter, based on heterogeneously integrated ITO thin films into silicon photonics. Furthermore we show, that this device paradigm enables spectrally broadband operation across the entire telecommunication near infrared C-band. Such sub-wavelength short efficient and fast modulators monolithically integrated into Silicon platform open up new possibilities for high-density photonic circuitry, which is critical for high interconnect density of photonic neural networks or applications in GHz-fast optical phased-arrays, for example.
密集集成有源光子学是解决下一代片上网络中占用面积和能量预算问题的关键。然而，传统有源硅光电子学中微弱的光与物质相互作用要求相当大的器件长度。理想的有源材料选择应在易于集成到硅光子学平台的同时，具备高折射率调制能力。氧化铟锡（ITO）具备这些功能，并且最近已显示出有前景的调制能力。有趣的是，ITO的纳米级薄且统一的强折射率调制将混合等离子体中的高群折射率与纳米级光学模式协同结合。遵循这一设计范式，在此我们展示了一种光谱宽带、GHz级快速的马赫曾德尔干涉调制器，其通过95 V·μm的微小电压长度（VL）体现出高效率，该调制器基于将ITO薄膜异质集成到硅光子学中，部署了一个一微米的紧凑型静电可调等离子体移相器。此外，我们还表明，这种器件范式能够在整个电信近红外C波段实现光谱宽带操作。这种单片集成到硅平台中的亚波长短、高效且快速的调制器为高密度光子电路开辟了新的可能性，这对于光子神经网络的高互连密度或例如GHz级快速光学相控阵中的应用至关重要。
