nanophotonics

Nanophotonics is the field that studies and exploits light at nanometer scales, focusing on manipulating and confining photons to dimensions near or below the diffraction limit. It combines optics, plasmonics, nanofabrication, and materials science to control light–matter interactions with high spatial and temporal resolution.

Core concepts include surface plasmon polaritons at metal–dielectric interfaces, localized surface plasmon resonances in metal nanoparticles, and high-index dielectric nanoresonators that support Mie-type resonances. Dielectric nanophotonics aims to reduce losses while maintaining strong confinement. Metamaterials and photonic crystals enable unusual dispersion and light steering at the nanoscale, while graphene and other two-dimensional materials add tunability and nonlinear effects.

Platforms and methods commonly used in nanophotonics include metal and dielectric nanostructures, hybrid plasmonic–dielectric configurations, and quantum emitters. Fabrication techniques encompass electron-beam lithography, nanoimprint lithography, and bottom-up self-assembly. Characterization employs near-field optical microscopy, cathodoluminescence, and spectroscopy. Theoretical approaches rely on Maxwell’s equations, finite-difference time-domain (FDTD) methods, and eigenmode analyses.

Applications span highly sensitive biochemical and refractive-index sensing, enhanced spectroscopy (such as SERS and SEIRA), on-chip photonics and optical interconnects, nanoscale imaging and super-resolution techniques, and improvements in photovoltaics. Nanophotonics also supports quantum information processing through integrated photonic circuits and single-photon sources, as well as nonlinear optical functionalities at reduced power levels.

Challenges include intrinsic losses in metals, fabrication tolerances, CMOS integration, heat management, and reproducibility. Advances in hybrid materials, active tuning, and scalable manufacturing are driving the field toward broader practical impact.