Low voltage 12 GHz silicon optical electro-absorption modulator (EAM) using a Schottky diode for optical interconnectors in the C-band

Uiseok Jeong, Kwangwoong Kim, Kyungwoon Lee, Jinsik Kim, Jung Ho Park

Research output: Chapter in Book/Report/Conference proceedingConference contribution


A silicon optical electro-absorption modulator (EAM) operating at a high speed and low voltage was achieved by using a Schottky diode in the C-band (1530 nm ∼ 1570 nm). The optical modulation is demonstrated by the intensity change of guiding light due to the free-carrier absorption in the semiconductor to change its absorption coefficient, not conventional interference effects. The proposed EAM has lateral metal-semiconductor (MS) junctions that aid in maximizing the free carrier injection and extraction by a Schottky contact on the rib waveguide center. The rib waveguide structure of the modulator on the standard 220-nm silicon-on-insulator (SOI) platform has an etch depth of 80 nm and a width of 450 nm for the single-mode operation. The center of the rib waveguide is lightly doped with 1015 cm-3 indium, where light is mostly confined. The sides are heavily doped with 1020 cm-3 indium to contribute to the optical absorption change in the center. The depletion width in the middle region was drastically changed by a Schottky contact with bias. This design allowed a high overlap between the optical mode and carrier density variations in the center of the waveguide. To achieve a high speed operation, the travelling-wave type electrodes were designed to allow copropagation of electrical and optical signals along the waveguide. The measured results demonstrated a broad operational wavelength range of 40 nm with a uniform 3.9 dB modulation depth for a compact 25 μm modulation length with 1 Vpp driving voltage. The travelling-wave type electrodes enabled the modulator operating up to 26 GHz with 12 GHz of 3-dB electrooptic bandwidth, experimentally.

Original languageEnglish
Title of host publicationSilicon Photonics XV
EditorsGraham T. Reed, Andrew P. Knights
ISBN (Electronic)9781510633339
Publication statusPublished - 2020
EventSilicon Photonics XV 2020 - San Francisco, United States
Duration: 2020 Feb 32020 Feb 6

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceSilicon Photonics XV 2020
Country/TerritoryUnited States
CitySan Francisco

Bibliographical note

Funding Information:
This research was supported by the MSIT (Ministry of Science and ICT), Korea, under the ITRC (Information Technology Research Center) support program(IITP-2019-2015-0-00385) supervised by the IITP(Institute for Information & communications Technology Planning & Evaluation) and the Seoul R&BD Program (WR080951).

Publisher Copyright:
© 2020 SPIE.


  • C-band
  • Electro-Absorption
  • Plasma dispersion effect
  • SOI
  • Schottky diode
  • Silicon modulator
  • Waveguide

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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