Dispersive Fourier transformation for megahertz detection of coherent stokes and anti-stokes Raman spectra

OPTICS COMMUNICATIONS

卷:402

Article

Bohlin, Alexis¹  Patterson, Brian D.¹  Kliewer, Christopher J.¹ 

[1] Sandia Natl Labs, Livermore, CA 94551 USA

关键词: CARS;    Dispersive Fourier transformation;    Ultrafast spectroscopy;    Fiber detection;   

DOI  :  10.1016/j.optcom.2017.04.049

来源: Elsevier

【 摘 要 】

In many fields of study, from coherent Raman microscopy on living cells to time-resolved coherent Raman spectroscopy of gas-phase turbulence and combustion reaction dynamics, the need for the capability to time resolve fast dynamical and nonrepetitive processes has led to the continued development of high-speed coherent Raman methods and new high-repetition rate laser sources, such as pulse-burst laser systems. However, much less emphasis has been placed on our ability to detect shot to shot coherent Raman spectra at equivalently high scan rates, across the kilohertz to megahertz regime. This is beyond the capability of modern scientific charge coupled, device (CCD) cameras, for instance, as would be employed with a Czerny-Turner type spectrograph. As an alternative detection strategy with megahertz spectral detection rate, we demonstrate dispersive Fourier transformation detection of pulsed (similar to 90 ps) coherent Raman signals in the time-domain. Instead of reading the frequency domain signal out using a spectrometer and CCD, the signal is transformed into a time-domain waveform through dispersive Fourier transformation in a long single-mode fiber and read-out with a fast sampling photodiode and oscilloscope. Molecular O- and S-branch rotational sideband spectra from both N-2 and H-2 were acquired employing this scheme, and the waveform is fitted to show highly quantitative agreement with a molecular model. The total detection time for the rotational spectrum was 20 ns, indicating an upper limit to the detection frequency of similar to 50 MHz, significantly faster than any other reported spectrally-resolved coherent anti-Stokes Raman detection strategy to date. (C) 2017 Published by Elsevier B.V.

【 授权许可】

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