Gabriel Nagamine Gomez


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Nagamine Gomez

First Name

Gabriel

ORCID

0000-0002-4830-7357

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Publications 1 - 3 of 3
  • Diffraction of Light from Optical Fourier Surfaces
    Item type: Journal Article
    Glauser, Yannik M.; Maris, J.J. Erik; Brechbühler, Raphael; et al. (2025)
    ACS Photonics
    Diffractive surfaces shape optical wavefronts for applications in spectroscopy, high-speed communication, and imaging. The performance of these structures is primarily determined by how precisely they can be patterned. Fabrication constraints commonly lead to square-shaped, "binary" profiles that contain unwanted spatial frequencies that contaminate the diffraction. Recently, "wavy" surfaces (known as optical Fourier surfaces, OFSs) have been introduced that include only the desired spatial frequencies. However, the optical performance and reliability of these structures have not yet been experimentally tested with respect to models and simulations. Such a quantitative investigation could also provide previously unobtainable information about the diffraction process from the most fundamental diffractive surfaces-sinusoidally pure profiles. Here, we produce and study two classes of reflective OFSs: (i) single-sinusoidal profiles of varying depth and (ii) double-sinusoidal profiles with varying relative phase. After refining our fabrication procedure to obtain larger and deeper OFSs at higher yields, we find that the measured optical responses from our OFSs agree quantitatively with full electrodynamic simulations. In contrast, our measurements diverge from analytical scalar diffraction models routinely used by researchers to describe diffraction. Overall, our results confirm that OFSs provide a precise and powerful platform for Fourier-spectrum engineering, satisfying the growing demand for intricately patterned interfaces for applications in holography, augmented reality, and optical computing.
  • Spectroscopy of Single CdSe Magic-Sized Nanocrystals
    Item type: Journal Article
    Nagamine Gomez, Gabriel; Santen, Julian; Crimmann, Juri G.; et al. (2025)
    Nano Letters
    Magic-sized nanocrystals (MSNCs) are semiconductor crystallites that grow in discrete steps. They lead to samples that potentially contain a single size and shape (i.e., monodisperse). To understand the impact of “magic” sizes on optical performance, we study the emission of individual MSNCs at room temperature. We find that the single-MSNC line width dominates ensemble emission spectra. By examining MSNCs with different sizes and shells, we conclude that the observed single-particle line is consistent with coupling of excitons to acoustic surface phonons. This coupling and any residual size dispersity influence MSNCs more than standard quantum dots, which experience weaker confinement. When CdSe quantum dots with similar confinement are compared with small CdSe MSNCs (<2.7 nm diameter), MSNCs have narrower ensemble spectra. Our MSNCs are bright emitters (40–80% efficient) with strong photon antibunching [g⁽²⁾(0) ∼ 0.05], making them promising candidates for applications in optoelectronics and quantum information, where strong three-dimensional confinement is required.
  • High-Throughput Optical Identification and Statistical Analysis of Atomically Thin Semiconductors
    Item type: Journal Article
    Crimmann, Juri G.; Junker, Moritz N.; Glauser, Yannik M.; et al. (2025)
    Advanced Optical Materials
    Transition metal dichalcogenides (TMDs) are layered two-dimensional semiconductors explored for optoelectronic applications, ranging from light-emitting diodes to single-photon emitters. Such devices require monolayer TMDs, typically obtained through mechanical exfoliation followed by manual identification with a brightfield optical microscope. While this procedure provides high-quality crystals, the identification is time-intensive, low-throughput, and prone to human error, which significantly limits TMD research. Here, we report a simple and fully automated approach for high-throughput identification of TMD monolayers using photoluminescence microscopy. We demonstrate the identification of up to three monolayers per second, offering a 10000x efficiency increase compared to conventional search and verification is demonstrated. This ability allows us to measure geometric and photoluminescence-intensity features of more than 2400 monolayers and bilayers of WSe2, MoSe2, and MoS2. Due to these large numbers, we can study and quantify material properties previously inaccessible. For example, we show that the mean photoluminescence intensity from a monolayer correlates with its size due to reduced emission from its edges. Further, we observe large variations in brightness (up to 10x) from WSe2 monolayers of different batches produced by the same supplier. Therefore, our approach not only increases fabrication efficiency but also enhances sample quality for optoelectronic devices of atomically thin semiconductors.
Publications 1 - 3 of 3