A large large part of the activity of the group focuses on photonic crystals which are designed, modeled, measured and fabricated by the team in the clean room facility of the Centre. We study in particular the enhancement of non-linear interactions in photonic crystal nanocavities made of silicon, diamond, germanium or nitride materials: Second harmonic generation, frequency tripling, Raman emission, auto-oscillations, two-photon absorption photodetection, biosensing etc. We also investigate light emission in tensile strained germanium to provide efficient optical sources for silicon photonics. The historical part of the activity is dedicated to the local control of photonic energy and the enhancement of the interaction between light (photons) and matter (electrons, phonons) at the smallest nanometric scales. We like looking at semiconductor nanostructures with strong electronic confinement like semiconductor
self-assembled quantum dots. Self-assembled quantum dots are
semiconductor nanostructures with characteristic dimensions in the
nanometer or tens of nanometers
scale. Self-assembled quantum dots can be formed spontaneously by
lattice mismatched materials like InAs on GaAs or Ge on Si. The physics
and the potential applications of these nanostructures are incredibly
At the nanometer length scale, the motion of the carriers is governed
quantum mechanics and the energy levels are quantized just like atoms
molecules. From this point of view [of discrete energy levels],
quantum dots can be considered as artificial atoms inserted into a
matrix. However this picture is limited. The coupling of the carriers
the environment like the vibration modes of the crystals, leads to very
specific properties and interaction mechanisms. We account for the electron-phonon interaction in semiconductor quantum dots which leads to the formation of polarons (entangled electron-phonon quasiparticule), in particular in the far infrared spectral range: time-resolved relaxation and decoherence dynamics, non-linearity like second and third harmonic generation, multiband k.p modelling of the electronic structure and infrared spectroscopy going from ensemble to single quantum dot measurements corresponding to a sub-wavelength ultrasensitive absorption nanospectroscopy instrumentation.
See thepublications section (top bar) for an up-to-date overview of the activities.
The quantum dot group is part of the SANDiE european network of
excellence, that brings together 32 european leading groups in the
field of self-assembled semiconductor nanostructures.
QD Group advisor: Dr Sebastien Sauvage -
Phone : +33 1 70 27 05 10
Up-up-level : Centre for Nanoscience