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Time-resolved Raman spectroscopy through a single optical fibre using CMOS SPAD line arrays

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Original languageEnglish
Pages (from-to)30976-30986
Number of pages10
JournalOptics Express
Issue number25
StateAccepted/In press - 11 Dec 2017


Full exploitation of fibre Raman probes has been limited by the obstruction of
weak Raman signals by background fluorescence of the sample and the intrinsic Raman
signal of the delivery fibre. Here we utilised functionalised gold nanoshells (NS) to take
advantage of the surface-enhanced Raman spectroscopy (SERS) effect to enhance the pH
responsive spectrum of 4-mercaptobenzoic acid (MBA), however fibre background is still
dominant. Using the photon arrival time-resolving capability of a CMOS single photon
avalanche diode (SPAD) based line sensor we recover the SERS spectrum without fibre
background in a 10 s measurement. In this manner, pH sensing through a multimode fibre at a
low excitation power, that is safe for future in vivo applications, with short acquisition times
(10 or 60 s) is demonstrated. A measurement precision of ±0.07 pH units is thus achieved.

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