In nanophotonics, one of the most pressing challenges is how to fabricate low-loss, high-performance on-chip photonic devices using van der Waals materials. On April 13, a breakthrough was achieved by the research team led by Professor Xiao Yunfeng from Peking University’s School of Physics, in collaboration with Professor Zhipei Sun from Aalto University in Finland. They developed a versatile nanofabrication technique that leverages aluminum passivation to safeguard focused ion beam (FIB) technology. This innovation allows for the precise creation of photonic structures—such as microdisks and photonic crystals—on a variety of van der Waals materials, including h-BN, MoS₂, and GaSe.

The team successfully fabricated low-loss optical microcavities boasting intrinsic quality factors exceeding 10⁶. Experimental results confirmed that these microcavities can support highly efficient continuous-wave nonlinear optical processes, including second-harmonic generation, sum-frequency generation, and optical parametric amplification. This advancement paves the way for constructing low-loss, highly integrated on-chip photonic systems. The findings have been published in the prestigious journal Nature Materials.