Open AccessGe-on-Si waveguides for sensing in the molecular fingerprint regime
Author(s) -
Ugne Griškevičiūtė,
Ross W. Millar,
Kevin Gallacher,
J. Valente,
Douglas J. Paul
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.382356
Subject(s) - attenuated total reflection , materials science , infrared , optics , fourier transform infrared spectroscopy , waveguide , spectroscopy , absorption (acoustics) , optoelectronics , fourier transform , infrared spectroscopy , fourier transform spectroscopy , reflection (computer programming) , optical path , chemistry , physics , computer science , organic chemistry , quantum mechanics , programming language
Low loss, single mode, Ge-on-Si rib waveguides are used to demonstrated optical sensing in the molecular fingerprint region of the mid-infrared spectrum. Sensing is carried out using two spin-coated films, with strong absorption in the mid-infrared. These films are used to calibrate the modal overlap with an analyte, and therefore experimentally demonstrate the potential for Ge-on-Si waveguides for mid-infrared sensing applications. The results are compared to Fourier transform infrared spectroscopy measurements. The advantage of waveguide spectroscopy is demonstrated in terms of the increased optical interaction, and a new multi-path length approach is demonstrated to improve the dynamic range, which is not possible with conventional FTIR or attenuated total reflection (ATR) measurements. These results highlight the potential for Ge-on-Si as an integrated sensing platform for healthcare, pollution monitoring and defence applications.