Scientists Trap Light on a Chip for Millions of Cycles in Photonics Breakthrough

Light Trapped for Millions of Cycles

An international team led by Aalto University has achieved a dramatic leap in photonic chip performance by developing a fabrication method that allows atomically thin materials to trap light for millions of cycles with virtually no loss. The work, published in Nature Materials on the thirteenth of April, overcomes one of the longest-standing barriers in the field of integrated photonics.

The Problem With Fragile Materials

Van der Waals materials, ultra-thin layered crystals in the same family as graphene, have long attracted interest for photonics because their atomically smooth surfaces minimise light loss. However, standard nanofabrication tools such as focused ion beam lithography tend to destroy their delicate crystal structures, making them nearly impossible to shape into useful devices.

A Microscopic Suit of Armour

The Aalto-led team solved this by coating the materials with a thin layer of aluminium before carving them. This protective shield absorbs the destructive impact of the ion beam, allowing researchers to sculpt the material with sub-one-hundred-nanometre precision while preserving its crystal quality. Using this shielded approach, they created tiny circular structures called microdisks that trap light with extraordinary efficiency.

Record-Breaking Performance

The devices achieved quality factors above one million, meaning only about one part per million of light is lost per cycle. When the team tested second harmonic generation, a process that converts light from one frequency to another, they measured an efficiency increase of ten thousand times over previous records. The performance surpasses previous van der Waals resonant systems by three orders of magnitude.

What This Means for the Future

The breakthrough demonstrates that materials once considered too fragile to engineer can now serve as building blocks for next-generation photonic devices. The advance opens paths towards reconfigurable photonic circuits, quantum light sources, and highly sensitive optical sensors integrated directly on a chip, potentially transforming fields from telecommunications to quantum computing.