Chinese scientists have developed a photonic chip material that can be manufactured at scale.

Photonics chips are a critical foundation for the future information industry, and the industry has been actively seeking advanced materials that enable scalable manufacturing of these cutting-edge devices. A research team led by Ou Xin, a researcher at the Shanghai Institute of Microsystem and Information Technology under the Chinese Academy of Sciences, has achieved a groundbreaking breakthrough in this field. They have developed a lithium tantalate heterogeneous integration wafer and successfully used it to fabricate high-performance photonics chips. This remarkable achievement was published on May 8 in the international academic journal *Nature*.

Ouxin explained that, unlike electronic chips that use electric current as the information carrier, photonic chips rely on light waves to transmit data, enabling low power consumption, high bandwidth, and ultra-low latency. However, current photonic chips are still constrained by material and technological limitations, facing challenges such as relatively low efficiency, limited functionality, and higher costs.

Similar to how electronic chips etch circuits onto silicon wafers, the team has etched photonic chip waveguides onto a lithium tantalate heterogeneous integration wafer. This integration wafer features a "sandwich" structure composed of "silicon-silica-lithium tantalate," with the key element being the ultra-thin, high-quality single-crystal lithium tantalate film—approximately 600 nanometers thick—on top, along with the exceptional quality of the interface between this film and the underlying silica layer.

The successful fabrication of this thin film was made possible by the team's signature "secret weapon"—their hetero-integration technology known as the "Universal Ion Knife." "We inject ions about 600 nanometers beneath the surface of the lithium tantalate material, essentially embedding a precise array of 'miniature bombs' that allow us to 'slice off' a single-crystal thin film just one nanometer thick," explained Wang Chengli, the team’s researcher and first author of the paper. He added that when the resulting lithium tantalate film is combined with a silicon substrate, it gives rise to a lithium tantalate hetero-integrated wafer.

"Lithium tantalate thin films boast exceptional electro-optic conversion properties, can be manufactured at scale, and hold tremendous application potential. Compared to lithium niobate—another material widely regarded as a promising candidate for photonic chips—lithium tantalate films are easier and more cost-effective to produce, while also offering superior electro-optic modulation, minimal birefringence, a broader transparency window, and enhanced resistance to photorefractive effects. These advantages significantly expand the flexibility of optical design," said Ouxin.

The Ouxin team, in collaboration with Tobias Kippenberg’s group at the École Polytechnique Fédérale de Lausanne in Switzerland, has further developed an ultra-low-loss fabrication method for tantalum lithium photonic chip microfabrication. Meanwhile, leveraging the tantalum lithium photonic chip, the team successfully generated a soliton optical frequency comb for the first time on an X-cut electro-optic platform. Combined with the material’s electro-optic tunability, this breakthrough holds great promise for applications in areas such as LiDAR and precision measurements.