Optical Characterization of Nanoparticles and 2D Materials Using Quantitative Phase Microscopy

Samira Khadir
March 19th, 2018 SAMIRA KHADIR Institute Fresnel

The interaction of light with nanostructures including nanoparticles (0D), nanowires (1D) and 2D materials is a domain of research arising fundamental and technological interests. Given the increasing use of these materials in technological applications, it is highly desirable to study and experimentally characterize their optical properties. In this talk, I will introduce a new technique allowing the quantitative optical characterization of nanostructures [1]. This technique named quadriwave lateral shearing interferometry (QLSI) is a real time, wide field and quantitative light-microscopy technique enabling imaging of electromagnetic fields, providing complete information about both their intensity and phase. The interferometric nature of the measurements makes this technique highly sensitive; QLSI can easily detect wavefront distortions smaller than 1 nm. These attributes make QLSI a powerful tool for imaging and characterization of nanostructures. In this work, we focalize on the study of nanoparticules (0D) and 2D materials. In the case of 2D materials, like graphene, we show that QLSI allows a morphological characterisation of 2D materials with a high contrast. In addition, thanks to the recorded intensity and phase images, we are able to determine and locally map the optical properties of the 2D material, namely the complex refractive index and the complex optical conductivity in the whole visible range.

For 0D materials such as metallic and dielectric nanoparticles, I will show how the QLSI technique can be used to measure their complex polarizability without a prior assumption about the nature or the geometry of the considered nanoparticle.

Seminar, March 19, 2018, 12:00. ICFO’s Seminar Room

Hosted by Prof. Romain Quidant