Phononic crystals are periodic distributions of two elastic materials; however, in the case when one of these materials is a fluid, the system is called a sonic crystal (SC).Over the last 20 years, the exploitation of the particular dispersion relation of these structures has revealed very interesting physical properties. The existence of ranges of frequencies, called bandgaps (BGs), in which non-propagating modes can be excited in the system, has been observed in a wide range of frequencies due to the scalability of the systems. The explanation of these bandgaps implies the resolution of a complex eigenvalues problem for the Helmholtz equation.

The complex part of the eigenvalues has physical existence: they correspond to evanescent waves. The evanescent properties in periodic composites have shown several interesting possibilities as imaging with super-resolution. Other properties of the dispersion relation have been used to control the wave propagation through these periodic structures as the control the spatial dispersion of the waves inside the periodic structures in order to obtain both the self-collimating effect, negative refraction,…

On the other hand our group have worked intensively on the optimization of this systems using heuristic techniques as multiobjective genetic algorithms, allowing the design of tailored filters. Now our work is focused on another type of distributions of elastic materials, as the ones based on fractal geometry o quasi-uniform structures. Also, a big effort has been done in the funcional approximation of signals coming from acoustics experiments and the mathematical analysis of engineering devices based on Sonic Crystal, more specifically Sonic Crystal Acoustic Barriers (SCAB) that have been acoustically standardized as traffic noise reducing device.

Research Group: FUNAPHY