LKB - Optical Imaging in biogical and complex media


Principal Investigator : Sylvain Gigan

The group deals with light propagation in complex media, mainly disordered photonic systems where light is scattered in a very complex way, such as paint layers, paper, or biological tissues. Multiple scattering of coherent light generates extremely complex interference
patterns, called speckle. But despite the enormous complexity of the scattering process, we can exploit and control light propagation, in particular thanks to spatial light modulators. Our approach is particularly interesting for imaging, light-matter interactions, signal
processing, but also as windows to understand subtle mesoscopic physics effects.


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News and Events

Review article

publication of our review article on applications of wavefront shaping and coherent light in Photoacoustics (and vice-versa), written by S. Gigan and E. Bossy: E. Bossy and S. Gigan, Photoacoustics with coherent light, Photoacoustics, (2016) Read more

2 PhD graduations

Two PhD students graduated this month : Thomas Chaigne (thesis entitled « Control of scattered coherent light and photoacoustic imaging : toward light focusing in deep tissue and enhanced, sub-acoustic resolution photoacoustic imaging ») and Hugo Defienne (thesis entitled "Quantum walks of Photons in disordered media"). Congrats to them and good luck !
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new publication in PNAS

PNAS "Invariance property of wave scattering through disordered media" in collaboration with TU Wien (Group Stefan Rotter) and Institut Langevin (Group Rémi Carminati). Read more

a star(tup) is born

A spin-off company from the group "LightOn", aiming at performing optical computation "at the speed of light" has entered incubation Read more

Let there be lab

moving is not completely finished, but our new lab is already full and buzzing with activity
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Colloquium talk

Video of Sylvain Gigan's colloquium, covering last year's research of the group, at the colloquium of the physics department of ENS Read more

visiting Professor Rafael Piestun

We have welcomed Rafael Piestun (Professor at ECE University of Colorado, Boulder) in the group for 3 month. Read more

visiteur Professor Jerome Mertz (BU)

Jerome Mertz, professor at Boston University, is visiting the group during the month of July 2016. Read more

visiting Professor Xiaopeng Shao (Xi'an University)

We have welcome Prof. Shao, from Xidian university, for the month of November 2016.
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A star is born

Mickael Mounaix, our second year PhD student, seems to have taken a second job in male modeling and is featured in the call for paper of the upcoming CLEO conference 2017. Submit now 🙂
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Xmas group picture

Xmas LKB party at college de France, (partial) group picture. Left to right: Benneth, Tom, Rebecca, Mickael, Saroch, Tengfei, Tom, Notre-Dame.
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viewpoint : optical microscopy aims deep

a viewpoint in Nature Photonics on the roots and future of our field Read more

Review of Modern Physics: Mesoscopic Physics meet wave control

long awaited, our review paper with Stefan Rotter is finally out in APS's Review of Modern Physics, and made the cover "Light fields in complex media: Mesoscopic scattering meets wave control" Read more

Nanophotonics Sciencecamp

during the complex nanophotonics Sciencecamp, several current and past members got together, and we could take and 'past a present' group picture, with only few (dearly missed) persons!
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thesis Defense: Mickael Mounaix

Mickael (very) successfully defended his thesis on Nov 8th, entitled: "Matricial approaches for spatio-temporal control of light in multiple scattering media". Congratulation Dr. Mounaix and good luck for your future endeavors!
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Science publication : a surprising invariant of light in complex media

5 years in the making, our result on experimentally verifying a surprising invariance of light in complex media, namely that the average path length is independent of disorder, is finally published ... in Science! check it out! Read more

A review article in the

our work is featured (in french) in a review Article by Mickael, Hugo, an Sylvain in a review article "Photoniques" of the French Optical Society. Read more

PhD Prize for Mickael Mounaix

Mickael Mounaix has been awarded the "Chancellerie Prize" of the Paris Universities in the category "Science". Read more

Thesis Defense : Tom Sperber

our PhD student, Tom Sperber, successfully defended his thesis, co-supervised by Dr. Patrick Sebbah from Institut Langevin and Bar-Ilan University, entitled : Control of Light in Disordered Media with Gain : Wavefront Shaping the Pump in Fiber Amplifiers and Fiber Lasers". Congrats!
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Postdoctoral Researcher
visiting Students
PhD Student
  • Sylvain Gigan
  • Saroch Leedumrongwatthanakun
    PhD Student
  • Dr. Claudio Moretti
  • Antoine Boniface
  • Jonathan Dong
  • Louisiane Devaud
  • Dr. Mushegh Rafayelyan
    Short Bio: Mushegh Rafayelyan obtained his bachelor's and master's degrees at Yerevan State University (Armenia) in 2010 and 2012 respectively. In 2015 he obtained a PhD in Theoretical Physics from the same university (Thesis: "Optical properties of anisotropic metamaterials and metamaterial based cholesteric liquid crystals"). In 2017 he obtained a PhD in Lasers, Materials and Nanoscience from University of Bordeaux (France) (Thesis: "Singular beam shaping from spin-orbit flat optics", supervised by Etienne Brasselet). Since 2018 he is a postdoctoral researcher in Laboratoire Kastler-Brossel, at Ecole Normale Supérieure (ENS, Paris), in the group of Sylvain Gigan, working on optical computing. In general, his research interests focus on beam shaping, optical imaging, optical computing and machine learning, light-matter interactions, liquid crystal topological defects, singular optics, and nonlinear optics. List of Publications : [1]  M. Rafayelyan and E. Brasselet, “Spin-to-orbital angular momentum mapping of polychromatic light,” Physical review letters 120, 213903 (2018). [2]  M. Rafayelyan, G. Agez, and E. Brasselet, “Ultrabroadband gradient-pitch bragg-berry mirrors,” Physical Review A 96, 043862 (2017). [3]  M. Rafayelyan, “Singular beam shaping from spin-orbit flat optics,” Ph.D. thesis, Bordeaux (2017). [4]  M. Rafayelyan and E. Brasselet, “Laguerre–gaussian modal q-plates,” Optics letters 42, 1966–1969 (2017). [5]  G. Tkachenko, M. Rafayelyan, and E. Brasselet, “Spin-orbit optomechanics of optically levitated chiral bragg microspheres,”Physical Review A 95, 053839 (2017). [6]  A. Gevorgyan, M. Harutyunyan, K. Oganesyan, E. Ayryan, M. Hnatic, M. Rafayelyan, Y. V. Rostovtsev, and G. Kurizki,“Polarization properties of the cholesteric liquid crystals,” arXiv preprint arXiv:1704.03259 (2017). [7]  M. Rafayelyan and E. Brasselet, “Bragg-berry mirrors: reflective broadband q-plates,” Optics Letters 41, 3972–3975(2016).[8]  M. Rafayelyan, G. Tkachenko, and E. Brasselet, “Reflective spin-orbit geometric phase from chiral anisotropic optical media,” Physical review letters 116, 253902 (2016). [9]  H. Grigorian, A. Ayriyan, E. Chubarian, A. Piloyan, and M. Rafayelyan, “An algorithm for the simulation of the magnetized neutron star cooling,” EPJ Web of Conferences 108, 02025 (2016). [10]  M. Rafayelyan, “Light propagation in metamaterial based anisotropic layer,” Proceedings of the YSU, Physics Mathematics pp. 61–66 (2015). [11]  M. Rafayelyan and A. Gevorgyan, “Electromagnetic wave non-reciprocity in a homogeneous anisotropic uniaxial medium,”Modern Problems in Optics and Photonics Proceedings of the International Advanced Research Workshop 27, 44–47 (2010). [12]  A. H. Gevorgyan, R. B. Alaverdyan, H. Gharagulyan, M. S. Rafayelyan, and H. Grigoryan, “Diffusion in liquid crystals of two cholesterics with different pitches,” Journal of Nanophotonics 9, 093591 (2015). [13]  A. Gevorgyan and M. Rafayelyan, “Light propagation in anisotropic metamaterials. ii. reflection from the half-space,”Journal of Contemporary Physics (Armenian Academy of Sciences) 49, 12–19 (2014). [14]  H. Gharagulyan, H. Grigoryan, M. Rafayelyan, A. Gevorgyan, and R. Alaverdyan, “Reflection and transmission properties of light in chiral liquid-crystalline photonic structures with pitch gradient and the phenomenon of nonreciprocity,” Proceedings of the International Conference on Photonics, Optics and Laser Technology (PHOTOPTICS-2013) pp. 115–120 (2013). [15]  H. Grigoryan, H. Gharagulyan, M. Rafayelyan, A. Gevorgyan, and R. Alaverdyan, “Theoretical and experimental investi- gation of polarization and spectral properties of light in multilayer cholesteric liquid-crystalline systems,” Proceedings of the International Conference on Photonics, Optics and Laser Technology (PHOTOPTICS-2013) pp. 111–114 (2013). [16]  A. Gevorgyan and M. Rafayelyan, “Light propagation in anisotropic metamaterials. i. dispersion surfaces,” Journal of Contemporary Physics (Armenian Academy of Sciences) 48, 276–284 (2013). [17]  A. Gevorgyan and M. Rafayelyan, “Optics of anisotropic metamaterial based structurally chiral photonic crystals,” Journal of Optics 15, 125103 (2013). [18]  A. Gevorgyan, K. Oganesyan, R. Karapetyan, and M. Rafayelyan, “The photonic density of states and the light energy density in cholesteric liquid crystal cells,” Laser Physics Letters 10, 125802 (2013). [19]  M. Rafayelyan and A. Gevorgyan, “Optics of cholesteric liquid crystals with large both dielectric and magnetic anisotropies,” Molecular Crystals and Liquid Crystals 561, 185–193 (2012). [20]  A. Gevorgyan, M. Harutyunyan, K. Oganesyan, and M. Rafayelyan, “Cholesteric liquid crystals with tunable defect inside as polarization azimuth rotation amplifiers and polarization azimuth stabilizers,” Optik-International Journal for Light and Electron Optics 123, 2076–2081 (2012). [21]  M. Rafayelyan and A. Gevorgyan, “Dispersion surfaces and light propagation in homogeneous dielectric-magnetic uniaxial medium,” Journal of Physics: Conference Series 350, 012031 (2012). [22]  M. Rafayelyan and A. Gevorgyan, “Plane electromagnetic waves in a homogeneous anisotropic uniaxial medium having a double anisotropy and an arbitrary orientation of its optical axis,” International Conference on Laser Physics 2010 7998, 79980K (2011).
  • Dr. Bernhard Rauer
  • Dr. Michal Dabrowski
  • Dr. Lorenzo Valzania
  • Hilton Barbosa de Aguiar
    Junior Research Chair ENS
  • Fernando Soldevila Torres
  • Lei Zhu
  • Julien Guilbert


Observation of mean path length invariance in light-scattering media

R. Savo, R. Pierrat, U. Najar, R. Carminati, S. Rotter, S. Gigan, Science, 358, 765 (2017)

Light fields in complex media: Mesoscopic scattering meets wave control

Stefan Rotter, Sylvain Gigan, Rev. Mod. Phys. 89, 015005

Spatiotemporal coherent control of light through a multiple scattering medium with the multispectral transmission matrix

M. Mounaix, D. Andreoli, H. Defienne, G. Volpe, O. Katz, S. Grésillon, .S Gigan, Physical Review Letters



We welcome application from outstanding candidates, interested by the work of our group. Please contact us to learn about our current openings on various projects.

Master and Bachelor

You can find specific internship offers on the following website:

We also welcome application from skilled and motivated candidates on any ongoing projects of the group. Please apply directly via email with CV and motivation letter.



We have no specific position at the moment, but welcome application from skilled and motivated candidates.


We are always looking for talented & motivated scientists and students to join our group.

Check the open positions or send us your CV and motivation letter for application.




Laboratoire Kastler-Brossel Département de Physique Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris Cedex 05


Sylvain Gigan 

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