Events

Workshop 4, November 25th 2026 : Optical Spectroscopy of QDs

Come and join us remotely for the fourth Track the Twin workshop. On November 25th we will be hosting world leaders on spectroscopic methods to probe excited state dynamics in QDs. We will overview the theory and application behind state-of-the-art ultrafast spectroscopy, energy transfer, photonics and single QD measurements. We will be having presentations from Freddy Rabouw (Utrecht University), Ivo Tanghe (Ghent University), Francesco Meinardi  (University Milano-Bicocca) and Angelo Monguzzi (University Milano-Bicocca).

Please register by filling out the form below

Presentation Schedule:

9:30-11:00 Francesco Meinardi (University of Milano Bicocca)

Title: TBD

Abstract: TBD

11:30-13:00 Angelo Monguzzi (University of Milano Bicocca)

Title: Principles and uses of non-radiative energy transfer

Abstract: In this lecture, I will introduce the physics behind the non-radiative energy transfer processes following the Förster and Dexter models. We will discuss how this energy transport mechanism works from individual donor/acceptor pairs to solid state systems, and we will analyze several cases where the non-radiative energy transfer processes are employed in current technologies for photon managing, imaging and radiation detection.

14:30-16:00 Ivo Tanghe (Ghent University)

Title: From Materials to Photonic Devices: Probing Ultrafast Gain Dynamics with Transient Absorption Spectroscopy

Abstract: Transient absorption (TA) spectroscopy is a powerful technique for investigating ultrafast carrier dynamics in semiconductor materials, providing insight into processes such as carrier relaxation, recombination, and optical gain. Beyond characterizing the intrinsic properties of a material, extending pump-probe spectroscopy to integrated photonic structures offers opportunities to directly investigate the interplay between excited carrier populations and optical modes under device-relevant conditions.

In this talk, I will first introduce the principles of transient absorption spectroscopy and discuss its application to solution-processable semiconductors, with a particular focus on colloidal nanocrystals. Particular attention will be given to the analysis and interpretation of transient absorption data in the context of optical gain and laser applications. In the second half of the talk, I will illustrate how these techniques can be extended from materials to photonic devices through two examples. As a first example, I will discuss femtosecond transient absorption measurements on colloidal nanocrystal photonic crystal surface-emitting lasers, where the dynamics of the gain medium and its coupling to cavity resonances can be resolved simultaneously, allowing us to resolve stimulated emission dynamics on sub picosecond timescales. Combined with carrier-photon rate equation modeling, these measurements reveal signatures of stimulated-emission-driven carrier depletion, carrier-density pinning, and transient changes in the cavity refractive index. Second, I will discuss the extension of pump-probe spectroscopy to solution-processable semiconductors coupled to optical waveguides, enabling the investigation of ultrafast carrier and optical gain dynamics in an amplifier geometry.

Together, these examples demonstrate how transient absorption spectroscopy can bridge the gap between fundamental material characterization and the study of functional photonic devices, providing insight into the ultrafast processes governing optical gain, amplification, and lasing.

16:30-18:00 Freddy Rabouw (Utrecht University)

Title: Spectroscopy of single quantum dots

Abstract: My presentation will start with the basics of single quantum dot spectroscopy, highlighting the strategies to select signals from specific charge states and the information obtained from correlation functions. The second part will cover some of the development efforts in my group to obtain more information for single quantum dots and to improve the throughput of measurements.