arXiv subjects

Eleni Prountzou

Publications and source records attributed to Eleni Prountzou.

3 recordsLinked to original sources

arXiv2026

Electro-optical modulation of light polarization in a nonlocal lithium niobate metasurface

We report the experimental realization of a LiNbO3 metasurface for electro-optic modulation of light polarization in the telecommunication band. High-Q quasi-bound states in the continuum are emploied to enhance the modulation of amplitude and phase of an impinging beam by a driving electric field, leading to efficient polarization rotation and conversion. We quantified modulation effects under a CMOS-compatible bias at 1 MHz frequency, achieving a variation of 5% in the Stokes parameters and a variation of the polarization ellipse angles of about 3° for the transmitted light. These results demonstrate that dynamic polarization and phase modulation can be attained in a compact platform, highlighting the potential of high-Q resonant LiNbO3 metasurfaces for enhanced light-matter interaction in subwavelength electro-optic devices.

physics.optics↗

arXiv2026

Electro-Optic Modulation in Polycrystalline Barium Titanate Metasurfaces Enhanced by Poling

Electrically tunable metasurfaces leveraging the strong Pockel's effect in barium titanate (BaTiO$_3$ or BTO) are a promising platform for reconfigurable free-space optical devices. However, the high cost, limited scalability, and restricted substrate compatibility of epitaxial BTO films hinder its exploitation. Here, we demonstrate free-space optical modulators based on imprinted BTO metasurfaces with targeted designs for optical and electric field confinement within the active material. With resonances exhibiting high quality factors of up to 200, we demonstrate improved transmission modulation at sub-volt driving amplitudes and frequencies up to 5 MHz. Additional enhancement is achieved via ferroelectric domain alignment, resulting in up to 25 % higher modulation strength compared to the unbiased case and up to 75 % compared to previous demonstrations. This enhanced EO response, arising from the effective permittivity engineering and domain orientation in these polycrystalline metasurfaces, holds significant potential for scalable and efficient EO modulators and active metasurfaces.

physics.optics↗

arXiv2026

Solution-derived barium titanate waveguides for integrated electro-optic modulation

Metal oxides with strong nonlinear optical properties and wide transparency window are key materials for the development of compact and efficient photonic integrated circuits used for electro-optic modulators and entangled photon sources. Among them, barium titanate (BaTiO$_{3}$) is particularly attractive due to its large Pockels coefficient. However, its use has been limited by challenges in material synthesis and in nanopatterning, owing to its chemical stability and inertness. Here, we demonstrate a monolithic electro-optic modulator entirely based on solution-deposited BaTiO$_{3}$, fabricated through a bottom-up soft nanoimprinting lithography process. Fine-tuning the synthesis and nanofabrication enhances the optical properties of the polycrystalline material. By optimizing the process parameters, we achieve a reduction in propagation losses of two orders of magnitude, enabling efficient electro-optic modulation. This scalable, etch-free approach enables direct patterning of high-quality BaTiO$_{3}$ structures, establishing a new route for low-cost, large-scale integrated electro-optic devices entirely based on oxide material compatible with a wide range of substrates.

physics.optics↗