Van der Waals materials are usually added to silicon photonic chips as overlays rather than used as the platform itself. Researchers from Peking University, Aalto University and Shanxi University have developed a nanofabrication strategy for high-resolution patterning of a wide range of these materials, including insulators, semiconductors, ferroelectrics and their heterostructures.
With it, the team made low-loss microdisks, photonic crystals and metasurfaces, including microdisk resonators with quality factors above 106. These enabled efficient continuous-wave second-harmonic generation, sum-frequency generation and optical parametric amplification, with thermal tuning across the full free spectral range. From QMAT, Zhipei Sun's Photonics group at Aalto took part, including Xiaoqi Cui, Andreas Liapis and Henri Kaaripuro.
Figure: Wang et al., Nat. Mater. (2026), CC BY 4.0