Atomic and Molecular Physics, and Optics, Physics and Astronomy, General Physics and Astronomy, Surfaces and Interfaces
15
Scopus Publications
Scopus Publications
Gold-polymer hybrid metasurface for polarization-independent enhanced third harmonic generation in the ultraviolet Shroddha Mukhopadhyay, Ana Conde-Rubio, Jose Trull, Agustín Mihi, Michael Scalora, Maria Antonietta Vincenti, Crina Cojocaru Scientific Reports, 2026 We present a combined experimental and theoretical study of nonlinear light-matter interactions in a three-dimensional gold-polymer hybrid metasurface. In contrast to conventional two-dimensional designs, which by symmetry may support either transverse electric (TE) or transverse magnetic (TM) polarization, our volumetric architecture accepts both TE and TM modes simultaneously, reflecting the dimensionality and versatility required by the photonic devices. The metasurface comprises a periodic lattice of gold nanostructures embedded in a dielectric polymer matrix, creating complex metal-dielectric interfaces that sustain tightly confined plasmonic resonances. When driven by ultrafast near-infrared (NIR) pulses, these resonances concentrate optical energy at the nanoscale, enabling efficient third-harmonic generation and upconversion of visible light into the ultraviolet (UV) and deep-UV regimes with enhanced conversion efficiency. We perform spatial and temporal mapping of the nonlinear response under both TE and TM excitation. Our measurements reveal polarization-agnostic field enhancement and spectral tunability arising from the three-dimensional morphology-capabilities unattainable in planar metasurfaces, where two-dimensional symmetry inherently limits polarization flexibility and functional bandwidth. This quasi-3D platform provides a flexible design toolbox for polarization-independent UV and deep-UV light sources. Potential applications include high-resolution UV spectroscopy, optical multiplexing, data storage, and emerging quantum photonic architectures. By establishing fundamental insights into three-dimensional nonlinear metasurface behavior, our work paves the way for next-generation reconfigurable, multi-polarization nanophotonic devices.
High-harmonic generation from subwavelength silicon films Kent Hallman, Sven Stengel, Wallace Jaffray, Federico Belli, Marcello Ferrera, Maria Antonietta Vincenti, Domenico de Ceglia, Yuri Kivshar, Neset Akozbek, Shroddha Mukhopadhyay, Jose Trull, Crina Cojocaru, Michael Scalora Nanophotonics, 2025 Recent years have witnessed significant developments in the study of nonlinear properties of various materials at the nanoscale. Often, experimental results on harmonic generation are reported without the benefit of suitable theoretical models that allow assessment of conversion efficiencies compared to the material’s intrinsic properties. Here, we report experimental observations of even and odd harmonics up to the 7th, generated from a suspended subwavelength silicon film resonant in the UV range at 210 nm, the current limit of our detection system, using peak power densities of order 3 TW/cm2. We also highlight the time-varying properties of the dielectric function of silicon, which exhibits large changes under intense illumination. We explain the experimental data with a time domain, hydrodynamic-Maxwell approach broadly applicable to most optical materials. Our approach accounts simultaneously for surface and magnetic nonlinearities that generate even optical harmonics, as well as linear and nonlinear material dispersions beyond the third order to account for odd optical harmonics, plasma formation, and a phase locking mechanism that makes the generation of high harmonics possible deep into the UV range, where semiconductors like silicon start operating in a metallic regime.
Harmonic generation from aluminium and gold nanolayers and nanogratings: bound and hot electron contributions International Conference on Metamaterials Photonic Crystals and Plasmonics, 2025
Harmonic generation from resonant metal-dielectric interfaces: contribution of bound and hot electrons Shroddha Mukhopadhyay, Crina Cojocaru, Maria Antonietta Vincenti, Kent Hallman, Michael Scalora, Jose Trull International Conference on Transparent Optical Networks, 2025 We report a combined experimental-theoretical investigation on second and third harmonic generation from aluminum and gold nanolayers and plasmonic nanostructures made of the same materials, with specific focus on bound and hot electron contributions to the nonlinear processes. Our experimental results are explained and validated by our unique microscopic, hydrodynamic model for linear and nonlinear interactions in metal surfaces. This study uncovers novel aspects of second harmonic generation in aluminum, with unusual and remarkable consequences of resonant absorption, namely an unexpectedly critical role that bound electrons play for light– matter interactions across the optical spectrum, suggesting that a different basic approach is required to fully explain the physics of surfaces.
Quasi three dimensional gold plasmonic metasurfaces for enhanced harmonic generation and light conversion to UV International Conference on Metamaterials Photonic Crystals and Plasmonics, 2025
Quasi three dimensional gold plasmonic metasurfaces for enhanced harmonic generation and light conversion to UV Shroddha Mukhopadhyay, Ana Conde-Rubio, Agustín Mihi, Jose Trull, Maria Antonietta Vincenti, Michael Scalora, Crina Cojocaru 2025 Conference on Lasers and Electro Optics Europe and European Quantum Electronics Conference CLEO Europe Eqec 2025, 2025 Plasmonic nanostructures under resonant conditions create strong spatial confinement of the electromagnetic field near the surface of the metal, which in turn enhances light-matter interaction and generates very large surface nonlinearities and enhanced frequency conversion, a fundamental step towards building coherent and efficient nano-scale UV light sources. The resonant properties are determined by the geometrical (shape, size, sharpness) and physical parameters (dielectric functions) of both the metal and surrounding dielectric materials [1–4].
Quasi three dimensional gold plasmonic metasurfaces for enhanced harmonic generation and light conversion to UV Shroddha Mukhopadhyay, Ana Conde-Rubio, Agustín Mihi, Jose Trull, Maria Antonietta Vincenti, Michael Scalora, Crina Cojocaru European Quantum Electronics Conference in Proceedings Conference on Lasers and Electro Optics Europe CLEO Europe 2025 and European Quantum Electronics Conference Eqec 2025, 2025 Plasmonic nanostructures under resonant conditions create strong spatial confinement of the electromagnetic field near the surface of the metal, which in turn enhances light-matter interaction and generates very large surface nonlinearities and enhanced frequency conversion, a fundamental step towards building coherent and efficient nano-scale UV light sources. The resonant properties are determined by the geometrical (shape, size, sharpness) and physical parameters (dielectric functions) of both the metal and surrounding dielectric materials [1–4].
Below the surface: Unraveling the intricacies of the nonlinear optical properties of aluminum through bound electrons M. Scalora, K. Hallman, S. Mukhopadhyay, S. Pruett, D. Zappa, E. Comini, D. de Ceglia, M. A. Vincenti, N. Akozbek, J. Trull, C. Cojocaru APL Photonics, 2024 By uncovering novel aspects of second harmonic generation in aluminum, we show that there are unusual and remarkable consequences of resonant absorption, namely an unexpectedly critical role that bound electrons play for light–matter interactions across the optical spectrum, suggesting that a different basic approach is required to fully explain the physics of surfaces. We tackle an issue that is never under consideration given the generic hostile conditions to the propagation of light under resonant absorption. Unlike most noble metals, aluminum displays Lorentz-like behavior and interband transitions centered near 810 nm, thus splitting the plasmonic range in an atypical manner and setting its linear and nonlinear optical properties apart. Studies of aluminum nanostructures having complex topologies abound, as do reported inconsistencies in the linear spectral response of surface plasmons and harmonic generation. Our experimental observations of second harmonic generation from aluminum nanolayers show that bound electrons are responsible for a unique signature neither predicted nor observed previously: a hole in the second harmonic spectrum. A hydrodynamic-Maxwell theory explains these findings exceptionally well and becomes the basis for renewed studies of surface physics.
Tailoring gold plasmonic metasurfaces for efficient harmonic generation S. Mukhopadhyay, C. Cojocaru, M. A. Vincenti, K. Hallman, A. Mihi, M. Scalora, J. Trull International Conference on Transparent Optical Networks, 2024 Harmonic generation on metal surfaces is an important field of research that explores the fundamental properties of surface physics. Surface plasmonic resonances and their spatial and temporal properties together with metasurfaces properties enable a wider understanding and control of light-matter interactions at the nanoscale. We report a combined experimental-theoretical investigation to monitor and control nanoscale electron dynamics with plasmons using ultrafast optical pulses in the visible and UV ranges. Our unique microscopic, hydrodynamic model for linear and nonlinear interactions in metal surfaces validates our experimental results. This work is part of an ongoing study of exploring nonlinear frequency conversion in the surface of metals and their intrinsic properties, starting from simple nanolayers and proceeding to two dimensional or more complicated nanostructures, as we explore, compare and discuss their efficiency, tailorability and applications.
Strong nonlinear efficiency enhancement in the visible and UV ranges from plasmonic gold nanogratings European Quantum Electronics Conference Eqec 2023 in Proceedings Conference on Lasers and Electro Optics Europe CLEO Europe 2023 and European Quantum Electronics Conference Eqec 2023 Part of Conference on Lasers and Electro Optics Europe CLEO Europe 2023 and European Quantum Electroni, 2023
Large Enhancement in Visible to UV Nonlinear Frequency Conversion by a Plasmonic Gold Nanograting International Conference on Metamaterials Photonic Crystals and Plasmonics, 2023
