Emerging Trends in Diffractive Optics and Metasurfaces

Dear Colleagues,

Rapid advances in nanofabrication and inverse‑design algorithms are redefining diffractive optics and metasurfaces, offering sub‑wavelength control over amplitude, phase, and polarization. This Special Issue highlights the latest breakthroughs that move the field beyond traditional diffractive elements and toward system‑level photonic solutions.

Key themes include, but are not limited to, the following:

1. Broadband dispersion‑engineered meta‑achromats that make imaging systems lighter, thinner, and chromatically corrected across the visible‑to‑IR spectrum.
2. Actively reconfigurable platforms—leveraging phase‑change materials, electro‑optic modulation, or MEMS actuation—for millisecond‑scale beam steering, adaptive focusing, and dynamic holography.
3. Nonlinear and quantum metastructures that enhance harmonic generation, spontaneous parametric processes, and single‑photon routing via an extreme local‑field confinement.
4. Large‑area wafer‑scale fabrication (nano‑imprint lithography, deep‑UV stepper patterning, and roll‑to‑roll processing) that bridges laboratory prototypes with industrial production.
5. Data‑driven topology‑optimized design frameworks that couple full‑wave solvers with machine‑learning surrogates in order to explore vast design spaces and realize multifunctional devices.
6. Lab‑on‑chip biosensing metasurfaces that integrate microfluidics with high‑Q resonators or plasmonic nano‑antennas for real‑time, label‑free detection of proteins, nucleic acids, and single‑molecule events.

Collectively, these developments are catalyzing disruptive applications in AR/VR head‑up displays, LiDAR, free‑space optical links, point‑of‑care diagnostics, and spaceborne instrumentation. By mapping both the scientific frontiers and emerging industrial pipelines, this Special Issue seeks to guide researchers toward the next wave of compact, energy‑efficient, and mass‑manufacturable photonic technologies.

Dr. Weiwei Liu
Guest Editor

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