Near-Field Optical Nanopatterning of Graphene.

2D materials are emerging as transformative platforms for next-generation memory, sensing, photonic, and quantum devices due to their extraordinary optical, mechanical, and electronic properties. A key challenge is achieving controlled and precise nanopatterning to unlock tailored functionalities. This work uses a direct laser writing method to introduce a near-field-mediated nanopatterning technique that delivers ≈10-30 nm lateral and sub-5 nm vertical modification on graphene under ambient conditions. This approach uses a pulsed femtosecond laser in the visible wavelength range with scattering-type scanning near-field optical microscopy (s-SNOM), where the s-SNOM tip serves as a nanoscale probe. The resultant nanopatterns exhibit highly symmetric, periodic nanoscale holes with spherical perforations (nanopunch holes), with 5-25 nm dimensions. Importantly, nano- Fourier transform infrared spectroscopy reveals selective oxidative functionalization at the periphery of the nanopunch holes, highlighting a controlled surface modification of graphene. By finely tuning experimental parameters such as laser exposure time, the nanopatterning feature size ranging from 1-30 nm, and the resulting shapes from nanoscale elevated structures (nanoblister shape) to punched holes can be precisely modulated. This nanopatterning strategy achieves feature sizes at the sub-10 nm scale and represents an advancement toward fabricating all-2D material devices, setting new benchmark in nanoscale manufacturing for quantum and photonic technologies.