Indium-Tin-Oxide for High-performance Electro-optic Modulation

• Main Authors: Ma Zhizhen, Li Zhuoran, Liu Ke, Ye Chenran, Sorger Volker J.
• Format: Article
• Language: English
• Published: De Gruyter 2015-06-01
• Series: Nanophotonics
• Online Access: https://doi.org/10.1515/nanoph-2015-0006

Advances in opto-electronics are often led by discovery and development of materials featuring unique properties. Recently, the material class of transparent conductive oxides (TCO) has attracted attention for active photonic devices on-chip. In particular, indium tin oxide (ITO) is found to have refractive index changes on the order of unity. This property makes it possible to achieve electrooptic modulation of sub-wavelength device scales, when thin ITO films are interfaced with optical light confinement techniques such as found in plasmonics; optical modes are compressed to nanometer scale to create strong light-matter interactions. Here we review efforts towards utilizing this novel material for high performance and ultra-compact modulation. While high performance metrics are achieved experimentally, there are open questions pertaining to the permittivity modulation mechanism of ITO. Finally, we review a variety of optical and electrical properties of ITO for different processing conditions, and show that ITO-based plasmonic electro-optic modulators have the potential to significantly outperform diffractionlimited devices.