Passive frequency filters based on surface acoustic waves play a key role in modern radiofrequency telecommunication systems, enabling signal processing using high compactness components minimizing insertion losses and optimizing the energy consumption of the system RF stages. However, these devices do not allow for a voltage-controlled operating frequency or bandwidth. Regardless of the considered application, the capability to efficiently and accurately tune these filters represents a significant challenge for the improvement of on-board RF signal processing modules. In this context, the CRONOS project consists in investigating the electric charge band-gap concept in surface acoustic wave-based filtering devices for radio communication applications. The frequency band and the tuning capability will be entirely controlled electrically by connection though passive or active electronic circuits. This research project is motivated by the promising results (S. Degraeve "Cristaux phononiques accordables". Thèse de doctorat, Université des Sciences et Technologies de Lille-2013) obtained with piezoelectric phononic crystals whose band-gap can be controlled through a simple variable electrical impedance. They have been used to realize tunable acoustic resonators. In this case the resonator band-gap width and tuning range directly depend on the piezoelectric coupling coefficient, which represents the mechanical/electrical energy conversion factor. The CRONOS project aims at bringing this concept for surface acoustic waves up into RF frequency bands, namely the VHF and lower UHF bands (from 10 MHz to 1 GHz), targeting applications in military radio communication. Two different piezoelectric materials are selected (LiNbO3 and KNbO3) based on their properties in terms of coupling efficiency, viscoelastic loss coefficients, non-toxicity and/or ease of fabrication. The target tuning capabilities are ?f/f ˜ 10% for LiNbO3 and 30% for KNbO3. The CRONOS project main phases are planned as follows: •development of tunable phononic crystal concepts for surface acoustic waves, •design and realization of generic periodic structures whose propagation properties, as well as resonance and filtering characteristics are defined by electric connections or specific configurations, •realization and characterization of demonstrators, in order to validate the concepts and evaluate their relevance for RF filtering applications.

Optical Isolation (OI) is one of the corner stones in photonic circuits design. The need of this functionality will be even more striking for future complex applications where many laser diodes will be integrated on a single ship. In addition, future photonic integrated circuits will include many stages that will be cascaded to perform parallel and serial operations like modulation, amplification and detection. It will be mandatory to buffer those stages one from another by incorporating OI in between the stages. There is up today no industrial solution that allows for on-chip OI . ISOLYIG aims to use new paradigms based on assembling magnetic materials (YIG) within photonic circuits using molecular bonding. We believe that the fundamental advances we already achieved will permit the fabrication of an economically relevant demonstrator of on-chip OI within the time frame of the ISOLYIG project.