Plasmonic structures confine light in optical waveguides and resonators with sub-wavelength dimensions and are more compact than dielectric or semiconductor ones. Metallic structures concentrate optical field in visible or near infrared wavelength at a few nanometer scale where as optical modes in dielectric or resonators semiconductor-air have typical length of a few hundred nanometer. After the first research on isolated metallic nanostructures, the plasmonic community is focused on metallic integrated optical structures for sub wavelength devices. As an example, very compact structures wit T or L shape has been proposed using metallic nanostructures chains (optical guides with localised plasmons). These chains can be realized by nanotechnology on semiconductor substrate. The interest of these metallic integrated structures, as already mentioned is to reach an order of magnitude in the miniaturization of integrated photonic circuits. They allow to redirect light with arbitrary angle or to increase the density the optical waveguides in 2d without lateral coupling and cross talk between these guides. In this context, the object and originality at international level of the PLACIDO project is to study and realize the coupling between optical SOI and plasmonic waveguides, in particular chains of coupled gold nanostructures. It will also explore optical transmission on an extended wavelength range (1150-1600 nm), which allows addressing several potential applications: biological sensors, integrated and miniaturized photonic circuits at telecom wavelength. An other original aspect is the characterization and optimization methodology, based on experimental near field mapping of propagating electromagnetic fields along these structures by scanning near field optical probe with phase resolution. This experimental technique allows precise and direct experimental analysis of coupling mechanism with sub- wavelength spatial resolution. The proposal is organised in such way to focus on realization and optimisation of coupling between SOI and plasmonic waveguides. It organize around three tasks strongly linked : nanotechnology, conception and modelling, guided and near-field optical characterization. The first step will be focused on the technological realization of plasmonic waveguides on SOI. The second step will develop transition and coupling studies between SOI and plasmonic waveguides, supported by two complete cycles of conception-realization-characterization. At the end, the test of a two branches light plasmonic distributor on SOI substrate using TE or TM mode will validate the integrated concepts developed in this proposal.

The HERMES project has the ambitious goal of providing breakthrough technological solutions towards the implementation of ultra-fast (100 Gbit/s) short-range wireless communication systems at room temperature, significantly surpassing existing technologies such as Wi-Fi 7 (40 Gbit/s) and 5G mmWave (10 Gbit/s). Such a technology would be a breakthrough for applications like monitoring, security, or sensing/medical. Most of the current technology limits in terms of data rate, carrier frequency, dimensions, energy efficiency, controllability, and tunability, are intrinsically related to the use of conventional materials and standard architectures. The HERMES project aims at overcoming these limits by demonstrating novel components of this envisaged system (emitters, detectors, and interfaces) that combine the advantages of using graphene and other 2D nanomaterials (high carrier mobilities, tunable charge carrier density, long lifetime of plasma waves) with that of operating in the THz range (high bandwidth and data rates). The HERMES project has the ambition to design, fabricate and validate - a novel THz emitter made by using graphene and a novel THz detector made by using 2D nanomaterials, both integrated into silicon and working at room temperature; - novel all-optical and electro-optical interfaces between THz devices and optical communication links. These goals will be achieved by the HERMES international network of academic and industrial partners, well-balanced in terms of competencies, expertise, and resources. Given the past achievements of the partners, a starting TRL 2 is estimated, while the final one will be TRL 4. The planned research, training, knowledge transfer, and networking actions will foster long-lasting research collaborations, strengthening existing ties (many created within MSCA actions) and establishing new links. The success of the HERMES project has the potential to strengthen Europe’s position in wireless technologies (6G and beyond).