Programming light

Published in Nature, a study by the Politecnico di Milano on "programmable" optical circuits

“Programmable" optical circuits are today the new frontier of integrated photonics. Their potential has been published by the prestigious journal Nature, in a study carried out by the Politecnico di Milano together with Stanford University, the Max Planck Institute, the Massachusetts Institute of Technology, the Universiteit Gent and the Universitat Politècnica de València.

Photonics is experiencing a pervasive diffusion in many application contexts, and it is now necessary to have "general purpose" optical circuits that can be programmed directly by the end user. These circuits represent the optical version of the well-known FPGA (field programmable gate array) electronics, which contrast with specific circuits designed to perform a single function. This versatility makes it possible to have a single product for many different applications, therefore reduced research and development time, significant cost reduction and greater accessibility to these technologies.

Programmable optical circuits are completely generic objects that can be configured "on-demand" for a specific purpose. The strategy used most often is to set up on a photonic chip some interconnected optical tracks (mesh), whose nodes can be configured via software and can be managed through appropriate calibration and control algorithms. In this way, the light is distributed, redirected and recombined in such a way that it performs the desired function very quickly, and with low energy consumption. If you then want to change the function of the circuit, you can simply reprogram it, without having to physically replace it.

While it is still premature to think of photonic devices so advanced that they operate on light in a similar way to current electronic processors, we have come very close to the possibility of creating programmable photonic co-processors that are capable of processing data in the optical domain to perform classes of operations extremely efficiently

says Prof. Andrea Melloni, head of the Photonic Devices Lab at the Politecnico di Milano.

With the same optical circuitry, we can choose to carry out mathematical operations, implement artificial intelligence and machine learning systems, create networks of on-chip sensors and imaging systems, and manipulate quantum states of light. Furthermore, the rapid convergence between electronic and photonic technologies will soon lead to all this being possible on the same silicon chip

adds Prof. Francesco Morichetti, who heads up the Superpixels project for the Politecnico di Milano.

Our university collaborates in this research activity with the Photonic Devices Lab at Polifab, the university's micro and nanotechnology centre. The activity is funded by the European project Horizon2020 Superpixels, which aims to create new generation sensor and imaging systems by exploiting the manipulation of light signals on chips. 

For more information
The online study