Microsphere Self-Interference Lithography for Polarization-Controlled Laser Parallel Nanofabrication for Raman detection

We develop compact microsphere self-interference lithography via a single laser beam incident into a self-assembled dual-layered microsphere array to achieve parallel fabrication of periodic units with nanopatterns (PUNs). Interference units with tens of millions are achieved through micron-thick dual-layered microsphere arrays. The periodic units with nanoholes (NHs), nanogrooves (NGs), and nanoslots (NSs) can be fabricated by simply varying incident laser polarization states. The minimum linewidth is 75 nm (∼λ/4.5), and the single-shot exposure area is up to 1 cm2. An analytical model of polarization-dependent tri-beam interferences is developed to interpret the PUN formation. Au-coated PUNs demonstrate extraordinary performance for customized surface-enhanced Raman spectroscopy substrates, of which the polarization sensitivity can be regulated and the limit of detection is down to 3 × 10-10 M. The present work opens up new opportunities for high-throughput laser parallel nanofabrication for various applications.