Optical wireless may no longer have any obstacles. A study conducted by Prof. Andrea Melloni and Prof. Francesco Morichetti from the Department of Electronics, Information and Bioengineering – Politecnico di Milano together with Scuola Superiore Sant’Anna in Pisa, the University of Glasgow and Stanford University, and published in the prestigious journal Nature Photonics, has made it possible to create photonic chips that mathematically calculate the optimal shape of light to best pass through any environment, even one that is unknown or changing over time. I3N Lab, coordinated by Prof. Marco Sampietro from the Department of Electronics, Information and Bioengineering, also contributed to the research.
The problem is well known: light is sensitive to any form of obstacle, even very small ones. Think, for example, of how we see objects when looking through a frosted window or simply when our glasses get foggy. The effect is quite similar on a beam of light carrying data streams in optical wireless systems: the information, while still present, is completely distorted and extremely difficult to retrieve.
The devices developed in this research are small silicon chips that serve as smart transceivers: working in pairs, they can automatically and indipendently 'calculate' what shape a beam of light needs to be in order to pass through a generic environment with maximum efficiency. And that’s not all: they can also generate multiple overlapping beams, each with its own shape, and direct them without them interfering with each other; in this way, the transmission capacity is greatly increased, just as required by next-generation wireless systems.
The chips developed at DEIB’s Photonic Devices Lab are mathematical processors that make calculations with light very quickly and efficiently, almost with no energy consumption. The optical beams are generated through simple algebraic operations, essentially sums and multiplications, performed directly on the light signals and transmitted by micro-antennas directly integrated on the chips. This technology offers many advantages: extremely easy processing, high energy efficiency and an enormous bandwidth exceeding 5000 GHz.
Analogue computing using optical processors is crucial in numerous application scenarios that include mathematical accelerators for neuromorphic systems, high-performance computing and artificial intelligence, quantum computers and cryptography, advanced localisation, positioning and sensor systems, and in general, in all systems where the processing of large amounts of data at very high speed is required.
