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Proceedings Paper

All-silicon transparent conducting oxide-integrated electro-optical modulator
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Paper Abstract

An optical modulator is considered one of the most fundamental components in an optical data communication system as it acts as a linking device between the optical and electrical parts of the system. Electro-absorption (i.e. electro-optical) modulation is one popular scheme in designing optical modulators; however, minimizing the device footprint in siliconbased platforms acted as a challenge. Few years ago, “plasmonics” field emerged as a good candidate that could possibly further reduce silicon-based modulators’ footprint. Unfortunately, existence of metals introduced huge propagation losses. Recently, transparent conducting oxides (e.g. indium tin oxide “ITO”) have been intensively used as active media in electro-optical (EO) modulators. They have a metal-like plasmonic behavior with extremely lower losses.

Under no biasing voltage, ITO acts almost as a dielectric. However, by carefully tuning the biasing voltage, the free carrier concentration beneath the ITO surface is changed. This allows a dramatic alteration in the complex permittivity of the ITO reaching an epsilon-near-zero (ENZ) value at some point. At this region, the ITO acts as a metal and a plasmonic mode is present at an ITO-dielectric interface. A heavily doped silicon slab can be used as a contact for the gating voltage to be applied on in order to accumulate free carriers on the ITO surface.

In this work, an all-silicon indium tin oxide-integrated electro-optical modulator is designed. The modulator exhibits superior parameters (e.g. insertion loss and extinction ratio) that outperform the current modulators based on the same technology.

Paper Details

Date Published: 9 March 2018
PDF: 7 pages
Proc. SPIE 10535, Integrated Optics: Devices, Materials, and Technologies XXII, 1053520 (9 March 2018);
Show Author Affiliations
Mohamed M. Badr, American Univ. in Cairo (Egypt)
Mohamed Y. Abdelatty, American Univ. in Cairo (Egypt)
British Univ. in Egypt (Egypt)
Mohamed A. Swillam, American Univ. in Cairo (Egypt)

Published in SPIE Proceedings Vol. 10535:
Integrated Optics: Devices, Materials, and Technologies XXII
Sonia M. García-Blanco; Pavel Cheben, Editor(s)

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