Researchers from the University of Southampton (UK), and the Institut d’Optique in Bordeaux (France) have devised a new approach for controlling light in a silicon chip by bringing the concept of spatial light modulation to integrated optics.
Silicon photonics are forming the backbone of next-generation on-chip technologies and optical telecommunication, which are aimed at a wide range of emerging applications including optical interconnects, microwave photonic circuits, and integrated optical sensors.
Photonic chip functionality is usually hard-wired by design, however reconfigurable optical elements would allow light to be routed flexibly, opening up new applications in programmable photonic circuits.
Traditional spatial light modulators are based on liquid crystals or micro mirrors and provide many independently controllable pixels. This technology has revolutionised optics in recent years, with many applications in imaging and holography, adaptive optics and wavefront shaping of light through opaque media.
In their new work, presented in the April issue of the journal Optica, the team makes use of multimode interference (MMI) devices, which form a versatile class of integrated optical elements routinely used for splitting and recombining different signals on a chip. The geometry of the MMI predefines its characteristics at the fabrication stage.