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Proceedings Paper

Polarization modulated background-free hyperspectral stimulated Raman scattering microscopy (Conference Presentation)
Author(s): Marie-Andrée Houle; Marco Andreana; Andrew Ridsdale; Doug Moffatt; Rune Lausten; François Légaré; Albert Stolow

Paper Abstract

Stimulated Raman Scattering (SRS) microscopy is a nonlinear microscopy technique based on Raman vibrational resonances determined by the frequency difference between Pump and Stokes laser pulses. Modulation of one laser beam transfers the modulation to the other, as either a gain in Stokes (SRG) or a loss in Pump power (SRL). SRS microscopy does not exhibit the four-wave mixing nonresonant background characteristic of CARS microscopy. However, other background signals due to two-photon absorption, thermal lensing or cross-phase modulation (XPM) do reduce the detection sensitivity and can distort the hyperspectral scans. Phase sensitive lock-in detection can reduce contributions from two-photon absorption, which is out-of-phase for the SRG case. However, the background signal due to XPM, which can be in-phase with SRS, can reduce the detection sensitivity. We present a novel polarization modulation (PM) scheme in SRS microscopy which greatly reduces the nonresonant XPM background, demonstrated here for the SRL case. Since many Raman vibrational transitions are parallel polarized, the SRS signal is maximum (minimum) when the polarizations of the pump and the Stokes beams are parallel (perpendicular). However, in both parallel and perpendicular Pump-Stokes geometries, XPM is non-zero in many media. Therefore, PM can remove the XPM background without significantly reducing the SRS signal. Our results show that the PM-SRS successfully removes the nonresonant signal due to XPM. High imaging contrast is observed, concomitant with high sensitivity at very low analyte concentrations and undistorted Raman spectra.

Paper Details

Date Published: 27 April 2016
PDF: 1 pages
Proc. SPIE 9712, Multiphoton Microscopy in the Biomedical Sciences XVI, 97120K (27 April 2016); doi: 10.1117/12.2209416
Show Author Affiliations
Marie-Andrée Houle, Institut National de la Recherche Scientifique (Canada)
Marco Andreana, National Research Council Canada (Canada)
Univ. of Ottawa (Canada)
Andrew Ridsdale, National Research Council Canada (Canada)
Doug Moffatt, National Research Council Canada (Canada)
Rune Lausten, National Research Council Canada (Canada)
François Légaré, Institut National de la Recherche Scientifique (Canada)
Albert Stolow, National Research Council Canada (Canada)
Univ. of Ottawa (Canada)

Published in SPIE Proceedings Vol. 9712:
Multiphoton Microscopy in the Biomedical Sciences XVI
Ammasi Periasamy; Peter T. C. So; Karsten König, Editor(s)

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