Laser light has revolutionized countless aspects of our societies and is at the foundation of a plethora of fields. In particular, communications heavily rely nowadays on the use of light to ensure a diffused access to high-speed connectivity. Whereas in the past the focus has mainly been on the development of fiber-optic communication networks, interest in free-space optical communications has grown again in recent years. Modulated light beams propagating in the free space instead of an optical fiber can be used to establish a high-capacity communication channel between two terminals with a simplified infrastructure and maintaining the link even if the terminals are moving. Beside many terrestrial applications, e.g. as a solution to connect rural and remote areas where optical fibers are difficult to lay, the use of free-space optical communications is also intensely studied in satellite-to-ground and satellite-to-satellite links. Despite this tremendous potential, the widespread application of free-space optical technologies is currently limited by the devices required to generate, shape, and point optical beams. These systems mostly rely on conventional optical components (e.g. lenses and mirrors) and mechanical assemblies. This makes them bulky, slow and costly. The solution envisioned by the project is to exploit photonic integration to realize these optical functionalities using a photonic chip. In particular, the original idea is to develop a new class of optical phased arrays, an on-chip device composed by many optical antennas, to generate, detect and point free-space laser beams. The project will exploit a multi-layer integration technology, metasurfaces and photonic circuits to achieve the high efficiency and large emission and detection areas that are required for long-distance communication links. Replacing motors, lenses and mirrors with a single, centimeter-scale chip through photonics integration will enable compact and lightweight devices and systems, reduced power consumption, novel functionalities, and robustness to mechanical vibrations, a groundbreaking achievement with extensive scientific, technical, and economic impact.
