Ultra-compact silicon nanophotonic modulator with broadband response
Ultra-compact silicon nanophotonic modulator with broadband response
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DOI：
10.1515/nanoph-2012-0009
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发表时间：
2012-01-01
期刊：
影响因子：
7.5
通讯作者：
Zhang, Xiang
中科院分区：
文献类型：
--
作者：
Sorger, Volker J.;Lanzillotti-Kimura, Norberto D.;Zhang, Xiang
电光调制器已被确定为光通信和信号处理的关键驱动器。随着光子电路的不断小型化，一个突出的目标是展示一个片上，超紧凑，电光调制器，而不牺牲带宽和调制强度。虽然已经证明了基于硅的电光调制器，但是由于弱的非线性电光特性，它们需要毫米量级的大器件覆盖区。调制强度可以通过部署高Q谐振器来增加，但是需要以显著牺牲带宽为代价。此外，设计挑战和温度调谐限制了这种基于谐振的调制器的部署。最近，已经研究了具有0.1dB/微米调制强度的电光调制应用的新型材料，如石墨烯，虽然显示出对纯硅器件的改进，但由于薄石墨烯层与硅波导的光学模式之间的低效重叠，这种设计仍然需要数十微米的器件长度。在这里，我们实验证明了一个超紧凑的，硅基，电光调制器具有创纪录的高1分贝每微米消光比在宽带宽范围内的1 μ m的环境条件。该器件基于等离子体金属氧化物半导体（MOS）波导，其有效地将光学模式的电场集中到由吸收系数可调的氧化铟锡（ITO）层组成的纳米薄区域中。调制机制源于电改变ITO层的自由载流子浓度，这显著增加了该MOS模式的损耗。将这种强光束调制无缝集成到现有的绝缘体上硅平台中，具有实现宽带、紧凑和高效通信链路和电路的巨大潜力。
Electro-optic modulators have been identified as the key drivers for optical communication and signal processing. With an ongoing miniaturization of photonic circuitries, an outstanding aim is to demonstrate an on-chip, ultra-compact, electro-optic modulator without sacrificing bandwidth and modulation strength. While silicon-based electro-optic modulators have been demonstrated, they require large device footprints of the order of millimeters as a result of weak non-linear electro-optical properties. The modulation strength can be increased by deploying a high-Q resonator, however with the trade-off of significantly sacrificing bandwidth. Furthermore, design challenges and temperature tuning limit the deployment of such resonance-based modulators. Recently, novel materials like graphene have been investigated for electro-optic modulation applications with a 0.1 dB per micrometer modulation strength, while showing an improvement over pure silicon devices, this design still requires device lengths of tens of micrometers due to the inefficient overlap between the thin graphene layer, and the optical mode of the silicon waveguide. Here we experimentally demonstrate an ultra-compact, silicon-based, electro-optic modulator with a record-high 1 dB per micrometer extinction ratio over a wide bandwidth range of 1 mu m in ambient conditions. The device is based on a plasmonic metal-oxide-semiconductor (MOS) waveguide, which efficiently concentrates the optical modes' electric field into a nanometer thin region comprised of an absorption coefficient- tuneable indium-tin-oxide (ITO) layer. The modulation mechanism originates from electrically changing the free carrier concentration of the ITO layer which dramatically increases the loss of this MOS mode. The seamless integration of such a strong optical beam modulation into an existing silicon-on-insulator platform bears significant potential towards broadband, compact and efficient communication links and circuits.