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Proceedings Paper

Low-loss delay lines with small footprint on a micron-scale SOI platform
Author(s): Matteo Cherchi; Mikko Harjanne; Konstantinos Vyrsokinos; Sami Ylinen; Markku Kapulainen; Tapani Vehmas; Timo Aalto
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Paper Abstract

Long and yet compact spiral waveguides based on micron-scale silicon strip waveguides has been enabled very recently by the introduction of the Euler bends. By ensuring effective broadband single mode operation of otherwise highly multimodal waveguides, these bends can have very low losses (<0.01 dB/90°) even with effective radii of a few microns. Together with the low propagation losses (< 0.15 dB/cm) of micron-scale strip waveguides, these bends enable centimeter-long delay lines with negligible losses and very small foot-print (< 1 mm2). In particular, interferometers delayed by ≈ 1 cm long spirals on one of the two arms have been fabricated on SOI wafers with both 3 um- and 4 umthick silicon layer, based on the well assessed process developed by VTT. The full devices have footprint smaller than 1.5 mm2, and they have been measured to have extinction ratios < 15 dB (reaching up to 21 dB) and about 3 dB excess losses. Functional characterization of the delayed interferometers at about 10 Gbps through demodulation of pseudorandom Differential Phase Shift Keying signals led to clearly opened eye diagrams with Q factor of 8.6 and bit error rates lower than 10-15.

Paper Details

Date Published: 27 February 2015
PDF: 7 pages
Proc. SPIE 9367, Silicon Photonics X, 93670A (27 February 2015); doi: 10.1117/12.2079560
Show Author Affiliations
Matteo Cherchi, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Mikko Harjanne, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Konstantinos Vyrsokinos, Aristotle Univ. of Thessaloniki (Greece)
Sami Ylinen, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Markku Kapulainen, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Tapani Vehmas, VTT Technical Research Ctr. of Finland Ltd. (Finland)
Timo Aalto, VTT Technical Research Ctr. of Finland Ltd. (Finland)

Published in SPIE Proceedings Vol. 9367:
Silicon Photonics X
Graham T. Reed; Michael R. Watts, Editor(s)

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