Time-resolved cathodoluminescence nanoscopy

Datum: 7 december 2018

Locatie: UAntwerp, Campus Groenenborger, Room U.408 - - Groenenborgerlaan 171 - 2020BE Antwerpen (route: UAntwerpen, Campus Groenenborger)

Tijdstip: 11.30 - 12.30 uur

Organisatie / co-organisatie: EMAT

Korte beschrijving: Friday Lecture by Albert Polman (Center for Nanophotonics, AMOLF, Amsterdam, NL)

Cathodoluminescence imaging spectroscopy (CL) is a powerful tool to characterize optical nanomaterials at deep-subwavelength spatial resolution. In CL, a 5-30 keV electron beam is raster-scanned over the surface while the emitted radiation is detected. The electron beam creates a single-cycle electric field oscillation that couples strongly to the electrons in the material, providing a spectrally broadband nanoscale probe of the local optical density of states. 

Here, we present two new CL microscopes that bring time resolution to CL spectroscopy. Using an ultrafast electrostatic beam blanker we create 30 ps electron pulses and measure the g(2) photon correlation spectra. A second instrument uses femtosecond pulsed-laser driven photoemission of the electron cathode to create 1 ps pulses and enables CL pump-probe spectroscopy.

We use CL to coherently excite plasmonic nanostructures and directly image localized and polaritonic modes at 10 nm spatial resolution. We measure the bandstructure of 2D topological photonic lattices of Si Mie scatterers. We make high-resolution maps of the g(2) 2-photon correlation and show CL from InGaAs quantum wells is composed of intense photon bunches. We end with presenting the first data from the time-resolved pump-probe CL microscope, directly probing the state transfer from NV- to NV0 centers in diamond.



Link: https://www.uantwerpen.be/en/research-groups/emat/news-and-activities/friday-lectures/