Time-Correlated Single Photon Raman Spectroscopy at MegaHertz Repetition Rates

Neil Finlayson, Andrea Usai, Gillian Brown, Heather McEwan, Ahmet Erdogan, Colin J Campbell, Robert K. Henderson

Research output: Contribution to journalLetterpeer-review

Abstract

Significant improvements in time-correlated single photon counting (TCSPC) Raman spectroscopy acquisition times can be achieved through exploitation of megahertz (MHz) laser repetition rates. We have developed a TCSPC Raman spectroscopy system based on a high peak power (>40W) pulsed laser, a high pulse repetition rate (40 MHz), a custom 𝑓/1.5 spectrometer, and a 512 spectral channel × 16 time bin single photon avalanche diode line sensor. We report millisecond Raman spectrum acquisition times, a peak Raman count rate of 104 kcps, and a linewidth aggregated count rate of 440 kcps with a diamond sample. This represents a three-order-of-magnitude increase in measured Raman count rate in comparison with a 104 kHz pulsed laser operating at 300 W and a four-order-of-magnitude increase over a 0.1 W pulsed laser operating at 40 MHz. A Raman-to-fluorescence ratio of 4.76 is achieved with a sesame oil sample at a 20 MHz repetition rate. Achieving high count rates and Raman-to-fluorescence ratios unlocks the potential of combined Raman/fluorescence lifetime spectroscopy for imaging and other short acquisition time applications.
Original languageEnglish
Pages (from-to)4104-4107
Number of pages4
JournalOptics Letters
Volume46
Issue number17
Early online date8 Jul 2021
DOIs
Publication statusPublished - 18 Aug 2021

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