Programming light

A Politecnico study published on Nature

“Programmable” optic circuits are the new frontier in integrated photonics. Their potential has been outlined in a study published in the prestigious magazine, Nature, by the Politecnico di Milano together with Stanford University, the Max Planck Institute, the Massachusetts Institute of Technology, Gent University and the Universitat Politècnica de València.

Photonics has permeated into many applications and contexts, and “general purpose” optical circuits that can be directly programmed by the end user are now a necessity. These circuits are the optical version of the well-known electronic FPGA (Field Programmable Gate Array), and differ from circuits specifically created to carry out just one unique function. This versatility means one product can be used for many applications, therefore reducing research and development times, as well as offering considerable cost savings and better accessibility to these technologies.

Programmable optical circuits are completely generic items that can be configured “on demand” to meet a particular purpose. The most commonly used strategy is to arrange a mesh of interconnecting optical guides on a photonic chip, whose nodes can be programmed via software and managed thanks to calibration and control algorithms. This means that the light is distributed, redirected and recombined to rapidly carry out the required function with minimal energy consumption. If the function carried out by the circuit needs to be changed, it just has to be reprogrammed and does not need to be physically replaced.