Advanced Methods of Semiconductor Research Seminar – Tuesday 16th of December 2025
We cordially invite you to Advanced Methods of Semiconductor Research Seminar on Tuesday 16th of December 2025 at 13:15 in room 321, building A-1, where there will be delivered a lecture:
Behind the scenes: Novel concepts for VCSEL cavities
by Floriana Mallwitz
from Institute of Physics and Astronomy, Technical University of Berlin
The lecture abstract is attached below.
———————————————————————————————————————
Vertical-Cavity Surface-Emitting Lasers (VCSELs) play a central role in modern photonics, enabling applications from high-speed data communication to sensing, LiDAR and emerging integrated photonic platforms. Their performance and functionality are intimately linked to the design of the optical cavity and to the microfabrication processes that define it. Advanced epitaxy, nanometer-precision lithography, and strict cleanroom environments are essential to realize the sub-micrometer features that govern modal control, spectral stability and device reproducibility.
In this seminar, I will provide an inside look at how VCSELs are fabricated and how novel cavity concepts are developed. Starting from the technological point of view, I will discuss how different design strategies, such as monolithic high-contrast gratings as top mirrors offering high spectral selectivity and post-growth tunability, photonic-crystal resonators, and laterally coupled apertures, enable engineered supermodes, enhanced coherence and new pathways toward high-speed modulation. These approaches illustrate how cavity geometry can be used to tailor optical feedback, exploit photon-photon resonance, and overcome limitations of conventional single-aperture devices.
The talk will combine fabrication insights with recent experimental results, highlighting how advanced cavity engineering can expand the performance landscape of VCSELs for next-generation photonic and communication systems.
