Dr. Hilton B. de Aguiar

Hilton is an experimentalist working with nonlinear microscopy and spectroscopy for probing complex soft matter systems. His PhD focused on using nonlinear optical tools to unravel molecular level details of colloidal systems (EPFL/Lausanne, jointly with Max-Planck Institute/Stuttgart, 2011). Currently, he holds a Junior Research Chair position at the prestigious Ecole Normale Superieure/Paris. His lab focuses on developments of computational imaging tools for enhanced Raman imaging, and also exploiting complex light for nonlinear optical applications. He has published 26 peer-reviewed papers and invited over 25 times to present his work world-wide.

Talk Title 

Deep, fast and few: enhanced molecular imaging via spatial light modulators

Abstract

Nonlinear optical processes are powerful approaches for probing complex soft matter systems (colloidal systems, biological specimens etc). For instance, by exploiting the intrinsic vibrational spectra of molecules, Coherent Raman Scattering microscopies offer unique capabilities such as high chemical selectivity imaging with video-rate speeds. Nevertheless, there still exists bottlenecks that hinder applications of nonlinear microspectroscopy for biological tissues. In particular, (i) the penetration depth in scattering media is remarkably shallow, and (ii) the datasets generated in vibrational microspectroscopy are overwhelmingly large. In this presentation, I will introduce the problem involved in these current challenges, and also present our recent results aiming at lowering these barriers. At the heart of these solutions is the spatial light modulator, a device that enables active addressing of various degrees of freedom of light fields (spatial, spectral, polarization) in phase, and/or amplitude.

To increase the penetration depth, we exploited concepts from wavefront shaping techniques, using phase-only spatial light modulators. These concepts are the cornerstone for manipulating multiply scattered light aiming at increasing penetration depth, as we have recently demonstrated >1000 enhancement of nonlinear signals and revival of a polarization state after a scattering medium [1]. These proof-of-principle experiments aimed at understanding fundamental limits of deep imaging using scattered light.

To address the overwhelming datasets generated in microspectroscopy, I will introduce the concept of compressive Raman imaging, mostly based on binary amplitude spatial light modulators: by exploiting sparsity [2] and redundancy [3] in Raman data sets, one can considerably simplify and speed up the spectral image acquisition. I will discuss the different ways of performing compressive Raman, in particular focusing on challenges for bio-imaging, and how we recently tackled them. With these outcomes, compressive Raman imaging soon may be routinely used by non-specialists of vibrational spectroscopy: that is, in a “blind” manner, due to the simpler workflow provided by the compressive Raman imaging framework.

[1] H. B. de Aguiar, S. Gigan, and S. Brasselet, Science Adv. 3, e1600743 (2017);
H. B. de Aguiar, S. Gigan, and S. Brasselet, Phys. Rev. A 94, 043830 (2016).
[2] P. Berto, C. Scotté, F. Galland, H. Rigneault, and H. B. de Aguiar, Opt. Lett. 42, 1696 (2017) ;
B. Sturm, F. Soldevila, E. Tajahuerce, S. Gigan, H. Rigneault, H. B. de Aguiar, ACS Photon. 6, 1409 (2019);
C. Scotte, H. B. de Aguiar, D. Marguet, E. Green, P. Bouzy, S. Vergnole, P. Winlove, N. Stone, H. Rigneault. Anal. Chem. 90, 7197 (2018).
[3] F. Soldevila, J. Dong, E. Tajahuerce, S. Gigan, H. B. de Aguiar, Optica 6, 341 (2019).