<

< [email protected] >

Professor Angela B. Seddon leads the Mid-Infrared (MIR) Photonics Group at The University of Nottingham, UK, with world-class facilities for fabricating MIR glass fibreoptics and chips. Her overall aim is to create a new paradigm in real-time, in vivo MIR medical molecular sensing, imaging and endoscopy for early, fast and reliable medical diagnosis and to assist precise removal of cancers during surgery. This new paradigm will be enabled through focused development of fibre devices and systems which are robust, functionally designed, safe, compact and cost effective and which are based on active and passive MIR optical fibres. She is author of >260 publications, including seven book chapters, and is a Fellow of the Society of Glass Technology, Royal Society of Chemistry, Institute of Materials, Minerals and Mining and a Fellow of SPIE.

Angela Seddon

Angela B. Seddon1*, David Furniss1, Zhuoqi Tang1, David Mabwa1, Joel Nunes1, Richard Crane1, Harriet Parnell1, Sendy Phang1, Emma Barney1, Mark Farries1, Trevor M. Benson1, Lukasz Sojka2 and Slawomir Sujecki1,2. 1Mid-Infrared Photonics Group, George Green Institute for Electromagnetics Research, University of Nottingham, UK.
2Telecommunications & Teleinformatics Department, Wroclaw University of Technology, Wroclaw, Poland.

MIR (mid-infrared) sensing has wide applicability for detecting molecular solids, liquids, solutions and gases. This is because many molecular species absorb light in the MIR spectral region. The MIR electromagnetic spectral region by definition runs from 3-50 microns’ wavelength. Many molecular absorptions lie within 3-15 microns’ wavelength, coinciding with the low loss window of chalcogenide glass fibreoptics and giving a ‘window of opportunity’ for a new generation of molecular sensing. Guided waves in MIR-transmitting chalcogenide-glass fibres, waveguides and resonators are showing promise for compact, portable and real-time molecular sensing with potential use across many sectors, such as in medicine, security, the environment, agriculture, pharmaceuticals and in manufacturing and chemical processing. New bright, MIR supercontinuum laser sources have been demonstrated both in chalcogenide-glass fibre and on-chip for wideband MIR molecular sensing. These supercontinuum fibre lasers are >1000x brighter than conventional blackbody MIR light sources. Also bright rare earth ion doped chalcogenide-glass fibre photoluminescence is being harnessed in narrow-band MIR molecular sensing. Many designs of chalcogenide-glass sensor heads have been realised for evanescent-field detection of molecules both in fibre and on-chip. Processing of chalcogenide-glasses pertinent to application in MIR molecular sensing devices will be presented. The necessary background to MIR optical sensing will be given, showing how it can be quantitative, of high contrast, fast and with high sensitivity and specificity.
We are particularly interested in vivo cancer diagnosis based on new MIR fibreoptics. MIR spectral signatures of cancers differ from those of normal tissue. The goal is for new portable, MIR spectroscopic sensing and imaging in healthcare, in vivo. This will give a faster cancer diagnosis than currently possible. At the heart of the MIR fibreoptic approach are the brand new fibre MIR-supercontinuum broadband laser sources (see Fig. 1). These are fibre lasers producing rainbow light – spatially coherent light of many frequencies across the MIR spectral region. Supercontinuum generation is a nonlinear optical phenomenon whereby narrow-line laser light is converted to laser light of broad spectral bandwidth.

Supercontinuum generation of visible light, was first achieved by Robert Alfano [1] but in borosilicate glasses. Our demonstration of a chalcogenide-glass fibre MIR supercontinua laser light  from 1.4 microns to 13.3 microns was the first truly to reveal the potential of MIR fibres to emit across the MIR molecular ”spectral fingerprint region” and a key first step towards portable, broadband MIR sources for real-time MIR molecular sensing [2]. The photonic technology is being put in place to develop new MIR platforms for sensing based on MIR fibreoptics [3] and key results will be presented.

References

[1] R.R. Alfano  and S.L. Shapiro: Emission in the region 4000 to 7000  Å via four-photon coupling in glass, Phys. Rev. Lett. 24 584-587 (1970).

[2] C.R. Petersen, U. Møller, I. Kubat, B. Zhou, S. Dupont, J. Ramsay, T.M. Benson, S. Sujecki, N. Abdel-Moneim, Z. Tang, D.  Furniss, A.B. Seddon, and O. Bang: Mid-infrared supercontinuum covering 1.4-13.3 μm molecular fingerprint region using ultra-high NA chalcogenide step-index fibre, Nature Photonics 8 830-834 (2014). This article was selected for Nature Photonics: News & Views, Nature Photonics 8 Nov (2014): Gr. Steinmeyer and J.S. Skibina: Entering the mid-infrared: the demonstration of chalcogenide fibre-based supercontinuum sources that reach beyond a wavelength of ten micrometres is set to have a major impact on spectroscopy and molecular sensing.

[3] A.B. Seddon, B. Napier, I. Lindsay, S. Lamrini, P.M. Moselund, N. Stone, O. Bang and M. Farries: Prospective on using fibre mid-infrared supercontinuum laser sources for in vivo spectral discrimination of disease, (Minireview) Analyst 143 5874-5887  2018 DOI: 10.1039/C8AN01396A