Periodic Reporting for period 3 - FORWARD (New Frontiers for Optoelectronics with Artificial Media)
Okres sprawozdawczy: 2021-11-01 do 2023-04-30
FORWARD has a strong multidisciplinary character as it lies at the crossroads of nanocrystal processing, nanofabrication, nanophotonics, condensed matter physics and optoelectronics. First, we will hybridize metallic metamaterials and CQDs, study the transport properties in these devices and develop metamaterial/ CQD photodetectors demonstrating the advantage of the hybridization. Second, we will induce classical cooperative effects between the different metamaterial inclusions and utilize this approach to fabricate hybrids LEDs capable of emitting optical vortices. Last, we will induce collective synchronizations among the CQDs and demonstrate hybrids LEDs that produce coherent and non-classical light.
The second thrust aims at developing LEDs emitting complex forms of light, and, in particular, vector vortex beams. The key challenge is that the formation of optical vortices requires coherence properties that are possessed by lasers—but not by LEDs that emit incoherent light. This thrust is also well under way. First, we have experimentally shown that this concept was valid in photoluminescence, using a local source of CQDs coupled with plasmonic holograms that imparts the necessary spatial coherence to the system (https://hal.archives-ouvertes.fr/hal-03111873). Secondly, we have demonstrated the photoluminescence of composite vector beams using extended incoherent sources. (https://hal.archives-ouvertes.fr/hal-03412641v1). Based on these results, we have engaged in the development of vortex emitting LEDs. This task is very difficult because LEDs are multilayer structures with a constrained environment for efficient carrier injection that is not compatible with the realizations in photoluminescence described previously. We have not yet been able to satisfy all the conditions for efficient carrier injection and vortex generation simultaneously.
The third thrust, chronologically started after the two others in full accordance with the work plan, has only recently begun. At this stage, we are trying to identify the most promising avenues to trigger a collective behaviour into our systems made of colloidal CQDs and optical metamaterials.
1) We have identified two carrier thermalization regimes within assemblies of PbS CQDs, allowing a unified understanding of their transport and luminescent properties;
2) We have introduced a new generation of optical metasurfaces that are specifically tailored to control the properties of thermalized active media (paper under review);
3) We have pushed the control of the spontaneous emission to a level usually achieved with lasers, by experimentally demonstrating the spontaneous emission of vector vortex beams;
4) We have realized extended incoherent sources emitting composite vector beams.
Among the expected results until the end of the project, we can list the realization of photodetectors based on an as-yet unexploited transport regime, the introduction of vortex emitting LEDs and the introduction of LEDs emitting coherent, but non-lasing light.