6533b829fe1ef96bd128a061

RESEARCH PRODUCT

Contrôle de nano-antennes optiques par une commande électrique : tuner plasmonique et transduction

subject

description

Optical nano-antennae are the new class of components to control light/matterinteraction at the nanoscale. These devices are operating in the visible to near infraredpart of the spectrum. The properties of these nano objects are controlled by theform, the size and the material.In the radio frequency domain, the tuner changes dynamically the operatingwavelength of the antenna. In this thesis work, we search to transfer this conceptto the nanoscale. The principle is to change the load impedance of the antenna, i.e.changing the optical index of the dielectric medium around the nano-object. Forthat we used anisotropic liquid cristal molecules. The value of the optical index iscontrolled by applying an external electrical static field. The effects on the spectraland scattering properties are demonstrated on a single dimer nano-antenna.However with the microwave antennae, we were interesting to the electronsphotonstransduction with an optical antenna. In this mind, we studied two differentsconfigurations. The first one concerns the use of carbon nanotubes placedin a field effect transistor configuration. These nano-objects emit light in the Telecomwavelength range by a radiative combination of electrons and holes. the secondconfiguration used planar tunnel junctions made by electromigration. In this case,the junctions are view as an optical gap antenna. Because the gap are very small(around 1 nm), we have studied the nonlinear optical response of these objects. Thisnonlinear optical characterization allows to determined the location of the tunneljunctions by an enhancement of the optical signal. The results about the properties(electrical and optical) of these tunnel junctions are presented.Once the transduction by the radio frequency antenna is achieved, this signalis transporting by a transmission line. By transposition at the nanoscale, the plasmonicswaveguides prove to be the most appropriate structure. In this case, theycould be used as an electrode or a waveguide. In this thesis work, we have studiedby leakage radiation microscopy, in the direct and reciprocal space, the simplestgeometry : plasmonic metal strips. We search to understand why these structureshave a cut-off width.