Abstract
Over the past decade, optical nanoantennas and metasurfaces have transformed our ability to manipulate light at subwavelength scales. Although optical absorption is often regarded as a parasitic loss, in resonant nanostructures it can instead be harnessed to generate heat and strong thermo-optical feedback, creating new opportunities for reconfigurable optics, nonlinear photonics, sensing, and energy conversion.[1]
In this talk, I will discuss how self-heating in silicon and germanium nanoresonators produces a nonlinear relationship between illumination intensity, temperature, and optical response, and how collective effects emerge in extended resonator arrays.[2,3] I will show how this physics enables functional nanophotonic systems, from thermally tunable metalenses[4] and dynamically self-modulating silicon metasurfaces[5] to engineered nanoscale temperature landscapes[6] and thermally enhanced molecular sensing.[7] The same thermo-optical feedback can also be exploited in quantum photonics, including the photothermal control of photon-pair generation.[8] Finally, I will discuss how nanophotonic structures can serve not only as devices, but also as probes of light-driven processes. Using nanostructure-enhanced in-situ second-harmonic generation at silicon–oxide–electrolyte interfaces, we access light-induced surface-potential dynamics and distinguish photocharging from photothermal changes in surface equilibria.[9] Together, these results highlight the opportunities offered by controlling and probing coupled light–heat–charge interactions at the nanoscale.
References
[1] O. C. Karaman, G. N. Naidu, A. Di Francescantonio, D. Dall’Aglio, E. N. Dayi, G. Davidova, and G. Tagliabue, “Thermally Reconfigurable Metasurfaces: From Linear Wavefront Control to Nonlinear and Chemical Functionality,” Nano Letters 26, 8941–8959 (2026). https://doi.org/10.1021/acs.nanolett.6c02092.
[2] T. V. Tsoulos and G. Tagliabue, “Self-induced thermo-optical effects in silicon and germanium dielectric nanoresonators,” Nanophotonics 9, 3849–3861 (2020). https://doi.org/10.1515/nanoph-2019-0534.
[3] A. Naef, E. Mohammadi, T. V. Tsoulos, and G. Tagliabue, “Light-Driven Thermo-Optical Effects in Nanoresonator Arrays,” Advanced Optical Materials 11, 2300698 (2023). https://doi.org/10.1002/adom.202300698.
[4] A. Archetti, R.-J. Lin, N. Restori, F. Kiani, T. V. Tsoulos, and G. Tagliabue, “Thermally Reconfigurable Metalens,” Nanophotonics 11, 3969–3980 (2022). https://doi.org/10.1515/nanoph-2022-0147.
[5] O. C. Karaman, G. N. Naidu, A. R. Bowman, E. N. Dayi, and G. Tagliabue, “Decoupling Optical and Thermal Dynamics in Dielectric Metasurfaces for Self-Encoded Photonic Control,” Laser & Photonics Reviews 19, e01014 (2025). https://doi.org/10.1002/lpor.202501014.
[6] G. N. Naidu, O. C. Karaman, and G. Tagliabue, “All-Dielectric Photo-Thermo-Optical Metasurfaces for Thermal Landscaping at the Nanoscale,” Advanced Optical Materials 14, e03403 (2026). https://doi.org/10.1002/adom.202503403.
[7] E. Mohammadi and G. Tagliabue, “Nanophotonic-Enhanced Thermal Circular Dichroism for Chiral Sensing,” ACS Photonics 12, 152–158 (2025). https://doi.org/10.1021/acsphotonics.4c01339.
[8] O. C. Karaman, H. Li, E. N. Dayi, C. Galland, and G. Tagliabue, “Photo-Thermally Tunable Photon-Pair Generation in Dielectric Metasurfaces,” ACS Nano 20, 4079–4087 (2026). https://doi.org/10.1021/acsnano.5c14740.
[9] T. Anwar, D. Dall’Aglio, M. Sabzehparvar, and G. Tagliabue, “Revealing Light-Driven Dynamics at Nanostructured Solid–Liquid Interfaces with In-Situ SHG,” arXiv:2510.08809 (2025).