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Coherent nonlinear spectroscopy with noisy broadband laser pulses


As a laser pulse is applied to an opaque scattering sample - such as biological tissue, paint, suspension, or plastic - its structure breaks down.  In space, a coherent beam breaks into a multitude of speckles.  In the spectral domain, the pulse is strongly modified due to the random transmission of the sample.  Both effects are deleterious for one's ability to use coherent techniques for the spectral analysis of the sample.

I will review our ongoing work aimed at implementing nonlinear spectroscopy with coherent broadband laser pulses that have passed through opaque samples.  Our goal is to use the quasi-random spectrum of light for extracting spectral information [1,2].  At the same time, we use two-dimensional spatial light modulators to correct for the spatial and temporal distortions due to the multiple scattering in opaque samples.

[1] E.A. Shapiro, S.O. Konorov, V. Milner, "Interference spectroscopy with coherent anti-Stokes Raman scattering of noisy broadband pulses", arXiv: 1104.1164.

[2] X.G. Xu, S.O. Konorov, J.W. Hepburn, V. Milner, "Noise autocorrelation spectroscopy with coherent Raman scattering", Nature Physics 4, 125 (2008).