Title

Epsilon-Near-Zero Si Slot-Waveguide Modulator

Keywords

electro-absorption modulator; epsilon-near-zero material; silicon photonics; transparent conducting oxide

Abstract

We experimentally demonstrate a broadband electro-absorption modulator exploiting indium tin oxide (ITO) as the active switching material. Si strip waveguides are fabricated and covered with 8 nm of HfO2 and 15 nm of ITO to form metal-oxide-semiconductor capacitor (MOS-C) based modulators. The mobile carrier density in the ITO film is controlled using a postanneal treatment to tune its permittivity ϵ to a near-zero value at the operation wavelength of 1550 nm. Using simulations and experiments, we demonstrate that realizing an epsilon-near-zero (ENZ) can enhance the modulation performance as it increases the overlap of the guided mode with the active ITO layer. We then show even greater benefits of this approach with Si waveguides featuring a central slot filled with ITO. Leveraging the ENZ effect, we achieve a notable 3 dB modulation depth of optical signals in a nonresonant waveguide structure with a length of 20 μm. The results provide insight into the design of very compact modulators for chip-scale optical links.

Publication Date

11-21-2018

Publication Title

ACS Photonics

Volume

5

Issue

11

Number of Pages

4484-4490

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/acsphotonics.8b00945

Socpus ID

85055211984 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85055211984

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