Seminar by Victor Kalt: "Numerical study of spontaneous emission in resonant waveguide gratings"

"Numerical study of spontaneous emission in resonant waveguide gratings""

Abstract

Resonant waveguide gratings (RWG) are used in security holograms as a protection against counterfeiting. The aim of the COULEUR project is the deposition of luminophores in the vicinity of RWGs to obtain more complex visual effects combining reflection and spontaneous emission. Studying the coupling between the RWG's resonant mode and a luminescent material requires the use efficient numerical methods for the computation of the Purcell factor and the LEE (Light Extraction Efficiency). In this talk, I will present numerical methods for the computation of those factors based on finite elements, RCWA and QNMs (quasi-normal modes). In addition to the resonant mode, RWGs can harbour bound state in the continuum (BIC) which are infinite Q-factor modes that cannot interact with incoming plane waves. I will show that the physical interpretation of the QNMs can be harnessed for the design of structures with a high luminescence efficiency through the introduction of a controlled disorder transforming the BIC into a quasi-BIC.

This seminar will be held in English.