DIrectional Light EMitting MetAsurfaces – DILEMMA

This proposal aims at developing integrated and directional UV light sources at room temperature based on not toxic III-V materials: AlGaN metasurfaces doped with GaN quantum dots. GaN quantum dots (QDs) will be coupled to AlGaN nanostructures acting as optical nanocavities hosting low order Mie resonances. The high refractive index of AlGaN will yield Mie resonances and play as optical nanocavities able to boost the Purcell factors and tailor the emission directivity. A major challenge addressed by this proposal is the integration of the GaN quantum dots directly inside the AlGaN nanocavities.
On one hand, we will leverage advanced theoretical and computational techniques developed by the theory group at Fresnel, relying on their finite elements and multipolar modal decomposition codes, to accurately and efficiently deal with multiscale light-matter interactions. The theoretical investigations will guide the design and optimize the nanostructure configuration to achieve directional emission and strong Purcell factors. On the other hand, the experimental group at CRHEA will develop integrated UV-visible light sources by doping with GaN quantum dots inside AlGaN particles. With respect to the more conventional GaAs and other III-V direct bandgap semiconductors, AlGaN is not toxic and its composition can be adjusted to emit light from the deep UV to the blue spectral region, leading to important applications in UV sterilization, low-cost, compact, reconfigurable or directional light sources (targeting application in micro-displays and others VR/AR devices).
Benefiting from the strong Purcell factor enhancement and nanoantenna scattering properties, we aim at controlling the emission directivity in view of realizing efficient and compact integrated UV directive light sources. We will explore new emission conditions achievable in assembly of spatially varying nanostructured emitters and address fundamental problems such as antenna-antenna near-field interaction and directional light emission from Mie resonances.
The challenge of this proposal not only lies in the doping of the high refractive index cavities with quantum dots (QDs) but also in their encapsulation and their precise positioning to address the expected conditions. Besides boosting the Purcell effect of the quantum dots, the coupling between QDs and arrays of Mie resonators will offer many degrees of freedom to tailor the directivity and shape the emission pattern. Addressing the light emission properties directly during the emission process opens up new avenues for incoherent light control. It could lead to disruptive new laser structures and coherent light emitting nanostructure arrays, reviving fundamental concepts such as directional Dicke superradiance or directional single photon emitters.