Ultrafast Cathodoluminescence Spectroscopy with Coherent Electron-Driven Photon Sources

Introduction

Exploring the optical responses of materials at the nanoscale is central to various fields of study, including quantum-sensitive measurement metrologies, photovoltaics, and optoelectronic devices. Electron probes have established themselves as important tools for visualizing nano-optical excitations with unprecedented spatial resolution.

Challenges in Visualization

However, controlling optical excitations and exploring their decoherence dynamics require visualizing the dynamics of the nano-world at sub-femtosecond temporal resolutions.

Project Overview

Within the context of our ERC Starting Grant "NanoBeam," we have established and proposed an electron-probe technique that not only allows us to explore dynamics at nanometer spatial and femtosecond temporal resolutions but also does so at a low cost.

Methodology

Unlike state-of-the-art ultrafast electron microscopy, our method does not rely on external laser excitations but rather on internal electron-driven photon sources.

Application Areas

To visualize the decoherence dynamics in a variety of systems, we plan to merge the electron-driven photon sources with a cathodoluminescence spectroscopy setup based on optical fiber technology. The systems we aim to explore include:

1. Quantum emitters and networks
2. Optical excitations of two-dimensional materials
3. Semiconducting optoelectronic devices

Design and Implementation

We will design piezo stages and sample holders that enable precise alignment and tuning of the sample, electron-driven photon sources, and fibers inside the microscope while efficiently collecting cathodoluminescence photons.

Photon Yield and Investigation

Our electron-driven photon sources are designed to facilitate a high photon yield, allowing for optimal investigation of nonlinear processes.

Testing and Verification

The instrument will be tested and verified for applications in mapping the decoherence dynamics of:

1. Quantum emitters coupled to photonic structures
2. Optical excitations in two-dimensional materials
3. Charge transfer dynamics in photovoltaic devices