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Title: Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide

Abstract

Here, epsilon-near-zero materials provide a new path for tailoring light-matter interactions at the nanoscale. In this paper, we analyze a compact electroabsorption modulator based on epsilon-near-zero confinement in transparent conducting oxide films. The non-resonant modulator operates through field-effect carrier density tuning. We compare the performance of modulators composed of two different conducting oxides, namely indium oxide (In2O3) and cadmium oxide (CdO), and show that better modulation performance is achieved when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. In particular, we show that non-resonant electroabsorption modulators with sub-micron lengths and greater than 5 dB extinction ratios may be achieved through the proper selection of high-mobility transparent conducting oxides, opening a path for device miniaturization and increased modulation depth.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1371811
Alternate Identifier(s):
OSTI ID: 1369305; OSTI ID: 1371812
Report Number(s):
SAND-2017-6855J
Journal ID: ISSN 1943-0655; 654886
Grant/Contract Number:
AC04-94AL85000; NA0003525
Resource Type:
Journal Article: Published Article
Journal Name:
IEEE Photonics Journal (Online)
Additional Journal Information:
Journal Name: IEEE Photonics Journal (Online); Journal Volume: 9; Journal Issue: 4; Journal ID: ISSN 1943-0655
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; epsilon-near-zero; sub-micrometer electroabsorption modulator; transparent conducting oxides; near-infrared; high-mobility materials; cadmium oxide

Citation Formats

Campione, Salvatore, Wood, Michael, Serkland, Darwin K., Parameswaran, S., Ihlefeld, Jon, Luk, Willie, Wendt, Joel, Geib, Kent, and Keeler, Gordon A.. Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide. United States: N. p., 2017. Web. doi:10.1109/JPHOT.2017.2723299.
Campione, Salvatore, Wood, Michael, Serkland, Darwin K., Parameswaran, S., Ihlefeld, Jon, Luk, Willie, Wendt, Joel, Geib, Kent, & Keeler, Gordon A.. Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide. United States. doi:10.1109/JPHOT.2017.2723299.
Campione, Salvatore, Wood, Michael, Serkland, Darwin K., Parameswaran, S., Ihlefeld, Jon, Luk, Willie, Wendt, Joel, Geib, Kent, and Keeler, Gordon A.. Thu . "Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide". United States. doi:10.1109/JPHOT.2017.2723299.
@article{osti_1371811,
title = {Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide},
author = {Campione, Salvatore and Wood, Michael and Serkland, Darwin K. and Parameswaran, S. and Ihlefeld, Jon and Luk, Willie and Wendt, Joel and Geib, Kent and Keeler, Gordon A.},
abstractNote = {Here, epsilon-near-zero materials provide a new path for tailoring light-matter interactions at the nanoscale. In this paper, we analyze a compact electroabsorption modulator based on epsilon-near-zero confinement in transparent conducting oxide films. The non-resonant modulator operates through field-effect carrier density tuning. We compare the performance of modulators composed of two different conducting oxides, namely indium oxide (In2O3) and cadmium oxide (CdO), and show that better modulation performance is achieved when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. In particular, we show that non-resonant electroabsorption modulators with sub-micron lengths and greater than 5 dB extinction ratios may be achieved through the proper selection of high-mobility transparent conducting oxides, opening a path for device miniaturization and increased modulation depth.},
doi = {10.1109/JPHOT.2017.2723299},
journal = {IEEE Photonics Journal (Online)},
number = 4,
volume = 9,
place = {United States},
year = {Thu Jul 06 00:00:00 EDT 2017},
month = {Thu Jul 06 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1109/JPHOT.2017.2723299

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  • Here, epsilon-near-zero materials provide a new path for tailoring light-matter interactions at the nanoscale. In this paper, we analyze a compact electroabsorption modulator based on epsilon-near-zero confinement in transparent conducting oxide films. The non-resonant modulator operates through field-effect carrier density tuning. We compare the performance of modulators composed of two different conducting oxides, namely indium oxide (In2O3) and cadmium oxide (CdO), and show that better modulation performance is achieved when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. In particular, we show that non-resonant electroabsorption modulators with sub-micron lengths and greater than 5 dB extinction ratios may be achievedmore » through the proper selection of high-mobility transparent conducting oxides, opening a path for device miniaturization and increased modulation depth.« less
  • Opmore » tical communication systems increasingly require electro-optical modulators that deliver high modulation speeds across a large optical bandwidth with a small device footprint and a CMOS-compatible fabrication process. Although silicon photonic modulators based on transparent conducting oxides (TCOs) have shown promise for delivering on these requirements, modulation speeds to date have been limited. Here, we describe the design, fabrication, and performance of a fast, compact electroabsorption modulator based on TCOs. The modulator works by using bias voltage to increase the carrier density in the conducting oxide, which changes the permittivity and hence optical attenuation by almost 10 dB. Under bias, light is tightly confined to the conducting oxide layer through nonresonant epsilon-near-zero (ENZ) effects, which enable modulation over a broad range of wavelengths in the telecommunications band. Our approach features simple integration with passive silicon waveguides, the use of stable inorganic materials, and the ability to modulate both transverse electric and magnetic polarizations with the same device design. Using a 4-μm-long modulator and a drive voltage of 2 V p p , we demonstrate digital modulation at rates of 2.5 Gb/s. We report broadband operation with a 6.5 dB extinction ratio across the 1530–1590 nm band and a 10 dB insertion loss. This work verifies that high-speed ENZ devices can be created using conducting oxide materials and paves the way for additional technology development that could have a broad impact on future optical communications systems.« less
  • Optical nonlocalities are elusive and hardly observable in traditional plasmonic materials like noble and alkali metals. Here we experimentally observe and theoretically model viscoelastic nonlocalities in the infrared optical response of a doped, cadmium oxide epsilon-near-zero thin film. The nonlocality is clearly detectable thanks to the low damping rate of conduction electrons and the virtual absence of interband transitions at infrared wavelengths. We describe the motion of conduction electrons using a hydrodynamic model for a viscoelastic fluid, and find excellent agreement with experimental results. The electrons’ elasticity blue-shifts the infrared plasmonic resonance associated with the main epsilon-near-zero mode, and triggersmore » the onset of higher-order resonances due to the excitation of electron-pressure modes above the bulk plasma frequency. We also provide evidence of the existence of nonlocal damping, i.e., viscosity, in the motion of optically-excited conduction electrons using a combination of spectroscopic ellipsometry data and predictions based on the viscoelastic hydrodynamic model.« less