Institut des
NanoSciences de Paris
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Soutenance de thèse de Thu Loan Nguyen - Jeudi 26 octobre 2017 à 9 h 30

Thu Loan Nguyen, doctorante dans l’équipe Nanosciences et optique, soutient sa thèse jeudi 26 octobre 2017 à 9 h 30

INSP - UPMC - 4 place Jussieu - 75005 Paris - Barre 22-23, 3e étage, salle 317

Development of polarimetric and emission pattern analysis : Applied to determine a single nanoplatelet dipole

Abstract

Control and optimization of nanomaterial emission properties, requires the coupling between nanoemitters and nanostructures for achieving higher directivity, quicker dynamics or for high finesse cavities spectral filtering. The requirements for emission control are the spectral tuning of the emitter to the nanostructures modes, the spatial positioning of the nanoemitter at the location of maximum intensity of the resonant nanostructure mode, and a proper orientation of the dipole nanoemitter. Whereas for the two first requirements, many strategies have been implemented, the control of the dipole orientation remains a challenge. In plasmonics, for example, efficient interaction can only be achieved for dipoles orthogonal to the metallic surface. The determination of the orientation of the emitting dipole is thus very crucial for plasmonics devices such as nano-antennas. In my thesis, I contributed to the development of a polarimetric method aiming at the analysis of a nanoemitter ?s emitting dipole and its orientation. I worked on the analytical model, performed experiments and analysed them. The model describes the emission of a dipole close to a plane interface in a wide range of realistic experimental conditions, including a very common case in plasmonics when the nanoemitter lies on a gold film, a situation for which the more standard defocused imaging method is not sufficiently sensitive to provide reliable quantitative information on the emitter’s orientation. With the same model, I also compute the emission diagram corresponding to the dipolar emission in far field for all these experimental conditions. By analysing the emission ?s polarization together with the emission pattern, I could determine the three-dimensional orientation of an emitting dipole. Then I applied this combining method to investigate the colloidal semiconducting CdSe/CdS nanoplatelets with different geometric structures : thin square platelets, thin rectangular platelets, and cubic platelets. I also established a relationship between the geometric structures of the platelets and the nature and orientation of their associated emitting dipoles.

Jury

  • DR(HDR) Marie-Claire Schanne-Klein (Laboratoire d’optique et bioscience, CNRS)
  • DR(HDR) Isabelle Robert-Philip (Laboratoire Charles Coulomb, Montpellier)
  • PR(HDR) Nicolas Treps (Laboratoire Kastler Brossel, Paris)
  • MCF(HDR) Alexandra Fragola (Laboratoire Photon et Matière, Paris)
  • MCF(HDR) Isabelle Maurin (Laboratoire de physique des lasers, Villetaneuse)
  • DR(HDR) Agnes Maitre (INSP, directrice de thèse)