Politecnico di Milano, Stanford University, the Scuola Superiore Sant’Anna in Pisa, and the University of Glasgow recently published in the journal Light: Science & Applications. The researchers have found a way to separate and distinguish optical beams even if they are superimposed, and the form in which they arrive at their destination is drastically changed and unknown. A programmable photonic processor built on a silicon chip of just 5 mm2 makes it possible.
The processor receives all the optical beams through a multitude of microscopic optical antennas integrated on the chip to manipulate them through a network of integrated interferometers and separate them on distinct optical fibers, eliminating mutual interference. This makes it possible to manage information quantities of over 5000 GHz, at least 100 times greater than current high-capacity wireless systems.
Even in free space, light can travel in the form of beams of different shapes, called “modes,” and each can carry a flow of information. Generating, manipulating, and receiving more modes means transmitting more information. Free space, however, is a more hostile, variable, and unpredictable environment for light than an optical fiber. Obstacles can alter the shape of the light beams, mix them and make them unrecognizable and unusable at first sight.
A peculiarity of the photonic processor is that it can self-configure very simply, without the need for complex control techniques. This configurability allows scalability to new versions of the device, capable of handling many beams simultaneously, increasing the transmission capacity. It can also adapt in real-time to compensate for effects introduced by moving obstacles or atmospheric turbulence, establishing and maintaining optimal optical connections.
This technology advances the processing of optical beams, helpful for self-driving vehicles, sensors and remote object recognition, portable and wearable devices for augmented reality, and investigative techniques for biomedical applications.