Optical seminar | 19 February 2021

Centre for Nano Optics, University of Southern Denmark
Monocrystalline gold flakes for linear and nonlinear plasmonics

Modern plasmonics strives to meet the demands of next-generation photonic technologies and open new research frontiers in mesoscopic solid-state physics. However, the success of these advancements largely depends on the reduction of electromagnetic losses in metallic materials, which constitutes the most ubiquitous problem of current nanoplasmonic devices.

One of the material platforms, which offers a possibility to mitigate these losses – (quasi-) monocrystalline gold flakes – emerged recently to supersede traditionally-used polycrystalline gold films. In this talk, I will present experimental investigations of the plasmonic properties of the gold flakes, which were performed in the course of my PhD studies.

First, I will consider optical response in the linear regime and demonstrate prospective applications in plasmonic devices. Second, I will discuss the nonlinear response arising from the interaction of monocrystalline gold surfaces with ultrashort light pulses, and present experiments revealing a strong anisotropic second-order nonlinear response which is markedly absent in polycrystalline films. In addition, I will show how two-photon luminescence microscopy can be used to study the nonlinear absorption dynamics in gold flakes that are a few tens of nanometers in thickness. Preliminary results indicate that hot carrier excitation and relaxation dynamics is significantly altered when the gold thickness approaches mesoscopic dimensions.