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Proceedings Paper

A single-lithography SOI rib waveguide sensing circuit with apodized low back-reflection surface grating fiber coupling
Author(s): Valentin J. Dubois; Mikael Antelius; Hans Sohlström; Kristinn B. Gylfason
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Paper Abstract

We present a single-lithography Mach-Zehnder interferometer sensor circuit, with integrated low back-reflection input and output grating couplers. The low back-reflection is accomplished by a duty cycle apodization optimized for coupling light between single-mode silica fibers and the nanometric silicon-on-insulator (SOI) rib-waveguides. We discuss the design, fabrication, and characterization of the circuit. The apodization profile of the gratings is algorithmically generated using eigenmode expansion based simulations and the integrated waveguides, splitters, and combiners are designed using finite element simulations. The maximum simulated coupling efficiencies of the gratings are 70% and the multimode interference splitters and combiners have a footprint of only 19.2×4.5 μm2. The devices are fabricated on an SOI wafer with a 220 nmdevice layer and 2 μm buried oxide, by a single electron beam lithography and plasma etching. We characterize the devices in the wavelength range from 1460-1580 nm and show a grating pass-band ripple of only 0.06 dB and grating coupling efficiency of 40% at 1530 nm. The integrated Mach-Zehnder interferometer has an extinction ratio of -18 dB at 1530 nm and between -13 and -19 dB over the whole 1460-1580 nm range.

Paper Details

Date Published: 10 May 2012
PDF: 12 pages
Proc. SPIE 8431, Silicon Photonics and Photonic Integrated Circuits III, 84311Q (10 May 2012); doi: 10.1117/12.921815
Show Author Affiliations
Valentin J. Dubois, Royal Institute of Technology (Sweden)
Mikael Antelius, Royal Institute of Technology (Sweden)
Hans Sohlström, Royal Institute of Technology (Sweden)
Kristinn B. Gylfason, Royal Institute of Technology (Sweden)


Published in SPIE Proceedings Vol. 8431:
Silicon Photonics and Photonic Integrated Circuits III
Laurent Vivien; Seppo K. Honkanen; Lorenzo Pavesi; Stefano Pelli, Editor(s)

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