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Silicon 'photonic molecules' for sensing applications (Conference Presentation)
Author(s): Hei Chit Leo Tsui; Osamah Alsalman; Abdullah Alodhayb; Hamad Albrithen; David E. Hagan; Andrew P. Knights; Matthew P. Halsall; Iain F. Crowe
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Paper Abstract

Silicon photonics micro-ring resonator (MRR) and Mach-Zehnder waveguide based sensors have attracted much attention in recent years because of their capacity for high sensitivity, small footprint and mass-scalable (low cost) potential. This type of sensor is based on the detection of changes in optical amplitude/phase due to small changes in local, near-field refractive index (RI) in the environment surrounding the waveguide device. Sensitivity to ever smaller changes in RI are sought, e.g. for vapour/gas based sensing, which may be realised by designing devices based around the slot waveguide. Furthermore, tailoring resonant line-shapes to generate asymmetric (or Fano-like) modes through series, parallel or ‘nested’ arrangements of coupled MRRs also demonstrates the potential for such sensitivity enhancement. This type of device is likely to be of interest, for example where sensing of volatile organic compounds (VOCs) is important, e.g. in industrial process and environmental monitoring. We demonstrate a number of such photonic sensing platforms, combining both the slot waveguide and both established and novel ‘photonic molecule’ structures, fabricated on silicon-on-insulator using standard foundry fabrication processes. Integrated TiN heaters provide the capacity for thermal tuning in order to manipulate the spectral characteristics of our devices and the sensitivity of the devices to a range of VOCs; benzene, toluene and xylene, are investigated as exemplars using a custom-made vapour delivery system. Sensor performance is established with the assistance of device modelling and comparison made with conventional single MRR devices as a reference. The potential of adding functional layers to the devices as a method for achieving chemical selectivity will also be discussed.

Paper Details

Date Published: 4 March 2019
Proc. SPIE 10923, Silicon Photonics XIV, 1092315 (4 March 2019); doi: 10.1117/12.2509919
Show Author Affiliations
Hei Chit Leo Tsui, The Photon Science Institute, The Univ. of Manchester (United Kingdom)
Osamah Alsalman, The Photon Science Institute, The Univ. of Manchester (United Kingdom)
Abdullah Alodhayb, King Saud Univ. (Saudi Arabia)
Hamad Albrithen, King Saud Univ. (Saudi Arabia)
David E. Hagan, McMaster Univ. (Canada)
Andrew P. Knights, McMaster Univ. (Canada)
Matthew P. Halsall, The Photon Science Institute, The Univ. of Manchester (United Kingdom)
Iain F. Crowe, The Photon Science Institute, The Univ. of Manchester (United Kingdom)

Published in SPIE Proceedings Vol. 10923:
Silicon Photonics XIV
Graham T. Reed; Andrew P. Knights, Editor(s)

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