Reconfigurable photonic integrated circuits (PICs) are devices that process signals using light instead of electricity. This allows them to perform complex operations — such as signal processing, quantum communications, or neural network computations — at the speed of light, with great energy efficiency.
However, to work properly, these circuits must be continuously monitored and adjusted: small changes in temperature or in the input signal can affect their performance. For this reason, they require an electronic system capable of tracking and correcting their behaviour in real time.
A research group from Politecnico di Milano,led by Prof. Marco Sampietro, has developed a new integrated solution to address this challenge, recently published in Light: Science & Applications.
The team designed an 8-channel electronic chip (ASIC) that automatically controls the optical components of a photonic circuit — in this case, a matrix of Mach–Zehnder Interferometers (MZIs), although the same technology can also be applied to other optical devices.
The key innovation was to shift the application-specific part of the system from the photonic chip to the electronic ASIC. This makes the control system easier to scale, more compact, and less power-hungry, while still keeping the ability to program each optical element independently.
To demonstrate its effectiveness, the researchers tested the system in a laboratory setup simulating a free-space optical transmission, affected by disturbances similar to atmospheric turbulence. The system was able to correct signal distortions in real time (up to 300 Hz), reconstructing the optical wave front directly in the optical domain, without the need for complex digital processing.
The result behaves like a “programmable lens”: just as a traditional lens focuses light onto a single point, this photonic circuit keeps the focus stable even when the signal changes or becomes distorted.
This work marks an important step toward full integration of electronics and photonics. In the future, we could see chips that tightly combine optical and electronic components, paving the way for ultrafast, compact devices for telecommunications and optical computing.
Read the paper