Journal of Modern Optics

Active and multifunctional metasurfaces

Metasurfaces have transformed the landscape of optical engineering by enabling unprecedented control over light with ultra-thin, planar structures. Through careful design of the geometry, size, orientation, and spatial arrangement of subwavelength-sized elements, metasurfaces allow the generation of arbitrarily complex wavefronts by manipulating the phase, amplitude, and polarization of incoming waves at each point.

Active metasurfaces, capable of real-time, dynamic tuning, have opened new possibilities for compact, reconfigurable systems from the microwave to infrared spectrum. By integrating tunable materials or external control mechanisms, they enable adaptive wavefront shaping, fueling advances in beam steering, computational imaging, dynamic holography, quantum photonics, and thermal management.

These innovations are also driving multifunctional and programmable metasurfaces, where a single structure can perform multiple tasks dynamically. Their role extends to computational metaphotonics, enabling direct execution of mathematical operations for optical signal processing, image analysis, and machine vision.

Despite progress, key challenges remain, including scalability, power efficiency, the need for fast, energy-efficient tuning mechanisms, and integration with existing technologies. The mechanisms behind ultrafast refractive index modulation, which enables time refraction, are still being explored, while the ability to individually control large arrays of subwavelength elements demands new fabrication and design strategies.

We invite researchers to contribute to this special issue, highlighting the latest advancements in active and multifunctional metasurfaces. We invite submissions exploring novel designs, materials, functionalities, and emerging applications, including:

• Innovative control methods, including approaches that address scalability and energy efficiency.
• Cutting-edge applications, such as directional wavefront steering and coherency control, adaptive wavefront shaping and aberration correction, quantum optics, thermal management, advanced sensing platforms, and high-resolution imaging techniques.
• Multifunctional metasurfaces, designed to perform multiple optical tasks either simultaneously or sequentially.
• Computational metasurfaces, engineered for optical operations contributing to computational metaphotonics.
• Active nonlocal metasurfaces, where active capabilities enhance functionality through strategic defect engineering in periodic lattices.
• High-frequency time-varying metasurfaces, enabling spatiotemporal control of electromagnetic waves for applications such as ultrafast wavefront shaping, efficient parametric amplification, and optical isolation.
• Intelligent metasurfaces, integrating AI-driven adaptive and cognitive functionalities for next-generation programmable photonic systems.

By contributing to this special issue, authors will help drive advancements in metasurface technologies and foster interdisciplinary collaboration in this rapidly evolving field.