Departmental Seminar

Time-resolved cathodoluminescence spectroscopy of optical metasurfaces

Professor Albert Polman
Center for Nanophotonics, AMOLF, Amsterdam

A fast electron beam passing through the surface of a polarizable material generates a single-cycle electric field oscillation near the surface that couples strongly to the free or bound electrons in the material. The ultrafast field oscillation presents a spectrally broadband excitation from deep UV to near IR, and the nanoscale electron probe size results in deep-subwavelength spatial excitation resolution. As such, electron beam excitation is one of the purest forms of optical excitation, directly addressing the quantum nature of optical matter. We study the generation of femtosecond plasmonic and photonic wave packets on metallic and dielectric metasurfaces by a 30 keV electron beam. We measure the angular radiation profile of optical metasurfaces and reconstruct the optical band structure, and determine the full polarization state of the emitted light. Finally, we introduce our newly built time-resolved cathodoluminescence microscope and present measurements of photon bunching statistics.

Albert Polman is program leader of the “Light Management in New Photovoltaic Materials” program at the NWO Institute AMOLF in Amsterdam, the Netherlands and Professor of Photonic Materials for Photovoltaics at the University of Amsterdam. Polman's research group focuses on nanophotovoltaics, the study of light management at the nanoscale to realize solar cells with ultra-high efficiency that can be made at low costs.

Polman is an elected member of the Royal Netherlands Academy of Arts and Sciences (KNAW), Fellow of the MRS, OSA, and recipient of ERC Advanced Investigator Grants (2011, 2016), the EPS Research into the Science of Light Prize (2017), the Physica Prize of the Dutch Physical Society (2014), the Julius Springer Award for Applied Physics (2014), the ENI Renewable Energy Award (2012), and the MRS Materials Innovation and Characterization Award (2012). Polman is co-founder of Delmic BV, that brings on the market an instrument for angle-resolved cathodoluminescence spectroscopy developed in his group.

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