The 15th META Conference — the International Conference on Metamaterials, Photonic Crystals, and Plasmonics — was held in Málaga, Spain, continuing its legacy as a leading event in the fields of nanophotonics, nanomaterials, and advanced electromagnetic materials.
Originally launched in 2002 as a NATO Advanced Research Workshop, META has since evolved into a major international forum for the scientific community. This year’s edition brought together a wide range of participants, including scientists, students, postdoctoral researchers, and representatives from industry, government, and funding agencies, fostering lively exchange and collaboration across disciplines. The conference covered a broad spectrum of cutting-edge topics, such as AI and machine learning for metamaterial design, topological photonics, quantum photonics, nanobiophotonics, sustainable materials, and flat optics. A rich program of presentations, keynote talks, and symposia offered insights into both theoretical developments and experimental breakthroughs.
Beyond the scientific sessions, the event featured a conference banquet, providing a relaxed environment for informal discussions and networking. The success of this 15th edition reaffirmed META’s role as a central meeting point for advancing research and innovation in photonics and metamaterials.
My presentation was part of Special Session 11: "Optical Antennas and Metasurfaces: Fundamentals and Applications of Enhanced Light-Matter Interactions," organized by Prof. Guillermo Acuna, Dr. Peter Zijlstra, and Dr. Hiroshi Sugimoto. I gave an invited talk titled: “Mechanically Tunable Optical Responses in Silicon Nanospheres Square Lattice Array Metasurface Fabricated via Bottom-Up Process.”
In this work, we study periodic structures that exhibit collective lattice resonances (CLR). CLRs have been utilized in applications such as optical sensing, structural coloration, and lasers. Metasurfaces featuring CLRs are typically fabricated via top-down nanofabrication techniques, including electron beam lithography, which allows precise realization of complex structures. However, this approach often suffers from low throughput, high cost, limited device size, and is generally restricted to rigid substrates. As an alternative, bottom-up assembly of nanoparticle-based nanoantennas—synthesized wet-chemically in large batches—into large-area CLR metasurfaces offers a way to overcome these limitations.
In our research, we focus on Mie-resonant silicon nanospheres (Si NSs) developed in our group. These Si NSs exhibit high sphericity, crystallinity, and size uniformity, which are essential for the bottom-up fabrication process, specifically capillarity-assisted particle assembly (CAPA).
We begin by presenting analytical calculations showing the extinction cross-section of both a single Si NS and a 2D lattice array. We then use finite-difference time-domain (FDTD) simulations to investigate how the CLR peak position shifts with lattice periodicity. Following this, we demonstrate the CAPA fabrication process and characterize the resulting metasurface, including surface morphology and reflectance spectra. Finally, we apply our sample to a custom-built stretching device and show reflectance modulation, including the in-situ lattice Kerker effect under varying strains.
META 2025 was the first international conference I have ever attended, and it was a truly enriching experience. The event gave me the opportunity to meet and engage with many researchers whose work is closely related to mine, as well as experts in other areas. I had three insightful discussions during different lunch breaks that were particularly memorable.
One of these was with a Chinese researcher from Technische Universität Dresden (Germany). His research focuses on functionalizing particle surfaces with polymers to improve electrode conductivity. In addition to discussing our research, he also shared valuable insights into the academic environment at German universities, which I found quite interesting.
Another discussion was with a Spanish researcher from the Instituto de Química Física Blas Cabrera (IQF) - CSIC (Spain). I asked him about the calculation strategy for periodic systems, and he kindly shared several useful papers with me. He also reviewed my code, offering helpful suggestions that will significantly improve my calculations.
I also had the chance to speak with Prof. Hervé Rinnert from Université de Lorraine (France), who delivered an excellent presentation on highly phosphorus-doped silicon nanocrystals obtained from P-doped SiO/SiO2 multilayers — a topic closely related to my own research interests. I asked him about potential applications of this work, and our conversation greatly deepened my understanding of the subject.
Outside of the conference, I took some time to explore Málaga, a beautiful seaside city. The people were energetic and friendly, and I enjoyed trying various local dishes such as paella and jamón (raw ham).
Overall, I had a wonderful time in Spain and am already looking forward to attending the next META conference.
