UltraCoherentCL · Ultrafast Cathodoluminescence Spectroscopy with Coherent Electron-Driven Photon Sources

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. However, controlling optical excitations and exploring their decoherence dynamics require visualizing the dynamics of the nano-world at sub-femtosecond temporal resolutions.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. 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.To visualize the decoherence dynamics in a variety of systems, including quantum emitters and networks, optical excitations of two-dimensional materials, and semiconducting optoelectronic devices, we plan to merge the electron-driven photon sources with a cathodoluminescence spectroscopy setup based on optical fiber technology. 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.Our electron-driven photon sources are designed to facilitate a high photon yield, allowing for optimal investigation of nonlinear processes. The instrument will be tested and verified for applications in mapping the decoherence dynamics of quantum emitters coupled to photonic structures, optical excitations in two-dimensional materials, and charge transfer dynamics in photovoltaic devices.""