The conference "Pioneers in the Underwater Dimension" was held at the Leonardo da Vinci National Museum of Science and Technology in Milan, organised by the National Committee Marconi.150 in collaboration with the Italian Navy. Among the invited speakers, one of the presentations that stood out was by Professor Francesco Braghin, a faculty member in the Department of Mechanical Engineering at Politecnico di Milano, who explored the challenges and innovations in underwater communication, focusing specifically on acoustic lenses.

Professor Braghin explained how acoustic lenses—devices designed to manipulate sound waves underwater—represent a promising solution for improving the transmission of acoustic signals in underwater environments. These lenses are made of metamaterials with variable properties to focus sound waves, reducing interference and enhancing the quality of the received signal. However, one of the main challenges is their high directivity, which can limit practical applications in real-world scenarios.

To address this issue, Professor Braghin and his team developed an innovative approach to designing acoustic lenses with low directivity and a broad frequency spectrum. Using an optimization algorithm, they were able to determine the density and bulk modulus of each metamaterial cell that makes up the lens. This method enables the design of lenses that maintain optimal performance across a wide range of frequencies and incoming wave directions, making them more suitable for various underwater applications. The concrete benefits of these optimized acoustic lenses include a significant improvement in the signal-to-noise ratio, which is crucial for ensuring more reliable and robust underwater communication. Moreover, the versatility of these lenses allows them to be used with both hydrophones, for signal reception, and projectors, for signal emission, expanding their potential applications in fields ranging from oceanographic research to military operations.

Professor Braghin's future research focuses on optimizing three-dimensional lenses and integrating them with advanced signal analysis techniques, such as beamforming. This integration aims to further enhance the precision and efficiency of underwater communications, opening up new opportunities for ocean exploration and surveillance.