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Proceedings Paper

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

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.

Paper Details

Date Published: 26 February 2020
PDF: 8 pages
Proc. SPIE 11285, Silicon Photonics XV, 112851L (26 February 2020); doi: 10.1117/12.2542479
Show Author Affiliations
Uiseok Jeong, Korea Univ. (Korea, Republic of)
Kwangwoong Kim, Nokia Bell Labs (United States)
Kyungwoon Lee, Institute of Convergence Technology KT (Korea, Republic of)
Jinsik Kim, Dongguk Univ. (Korea, Republic of)
Jung Ho Park, Korea Univ. (Korea, Republic of)

Published in SPIE Proceedings Vol. 11285:
Silicon Photonics XV
Graham T. Reed; Andrew P. Knights, Editor(s)

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