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.
|Title of host publication
|Silicon Photonics XV
|Graham T. Reed, Andrew P. Knights
|Published - 2020
|Silicon Photonics XV 2020 - San Francisco, United States
Duration: 2020 Feb 3 → 2020 Feb 6
|Proceedings of SPIE - The International Society for Optical Engineering
|Silicon Photonics XV 2020
|20/2/3 → 20/2/6
Bibliographical noteFunding 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).
© 2020 SPIE.
- Plasma dispersion effect
- Schottky diode
- Silicon modulator
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering