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Highlighted authors are members of the University of Jena.

  1. Raman signatures of single point defects in hexagonal boron nitride quantum emitters

    Year of publicationStatusReview pendingPublished in:npj Computational Materials C. Cholsuk, A. Çakan, V. Deckert, S. Suwanna, T. Vogl
    Point defects in solid-state quantum systems are vital for enabling single-photon emission at specific wavelengths, making their precise identification essential for advancing applications in quantum technologies. However, pinpointing the microscopic origins of these defects remains a challenge. In this work, we propose Raman spectroscopy as a robust strategy for defect identification. Using density functional theory, we characterize the Raman signatures of 100 defects in hexagonal boron nitride (hBN) spanning periodic groups III to VI, encompassing around 30,000 phonon modes. Our findings reveal that the local atomic environment plays a pivotal role in shaping the Raman lineshape. Furthermore, we demonstrate that Raman spectroscopy can differentiate defects based on their spin and charge states as well as strain-induced variations. The ability to resolve spin configurations offers a pathway to identifying defects with spins suitable for quantum sensing. Finally, an experimental concept using tip-enhanced Raman spectroscopy has been proposed in this work. Therefore, this study not only provides a comprehensive theoretical database of Raman spectra for hBN defects but also establishes a novel experimental framework to identify point defects. More broadly, our approach offers a universal method for defect identification in any quantum materials with spin configurations specific to any quantum application.
    University Bibliography Jena:
    fsu_mods_00029842External link

  2. Large-Scale Interlaboratory Study Along the Entire Process Chain of Laser Powder Bed Fusion: Bridging Variability, Standards, and Optimization across Metals and Polymers

    Year of publicationPublished in:Advanced Engineering Materials I. Kuşoğlu, S. Garg, A. Abel, P. Balachandran, S. Barcikowski, L. Becker, J. Bernsmann, J. Boseila, C. Broeckmann, M. Coskun, M. Dreyer, M. East, M. Easton, N. Ellendt, S. Gann, B. Gökce, M. Goßling, J. Greiner, P. Gruber, M. Grünewald, K. Gurung, N. Hantke, F. Hengsbach, H. Holländer, B. Van Hooreweder, K. Hoyer, Y. Huang, F. Huber, O. Kessler, B. Kısasöz, S. Kleszczynski, E. Koc, T. Kurzynowski, A. Kwade, S. Leupold, D. Liu, F. Lomo, A. Lüddecke, G. Luinstra, D. Mauchline, F. Meyer, L. Meyer, P. Middendorf, S. Nolte, M. Olejarczyk, L. Overmeyer, A. Pich, S. Platt, F. Radtke, R. Ramm, S. Rittinghaus, R. Rothfelder, J. Rudloff, M. Schaper, M. Scheck, J. Schleifenbaum, M. Schmidt, J. Sehrt, Y. Shabanga, A. Sommereyns, R. Steuer, L. Tisha, A. Toenjes, C. Tuck, A. Vaghar, B. Vrancken, Z. Wang, S. Weber, J. Wegner, B. Xu, Y. Yang, D. Zhang, E. Zhuravlev, A. Ziefuss
    University Bibliography Jena:
    fsu_mods_00025547External link

  4. Chirped Pulses Meet Quantum Dots: Innovations, Challenges, and Future Perspectives

    Year of publicationPublished in:Advanced quantum technologies F. Kappe, Y. Karli, G. Wilbur, R. Krämer, S. Ghosh, R. Schwarz, M. Kaiser, T. Bracht, D. Reiter, S. Nolte, K. Hall, G. Weihs, V. Remesh
    Shaped laser pulses have been remarkably effective in investigating various aspects of light–matter interactions spanning a broad range of research. Chirped laser pulses exhibiting a time-varying frequency, or quadratic spectral phase, form a crucial category in the group of shaped laser pulses. This type of pulses have made a ubiquitous presence from spectroscopic applications to developments in high-power laser technology, and from nanophotonics to quantum optical communication, ever since their introduction. In the case of quantum technologies recently, substantial efforts are being invested toward achieving a truly scalable architecture. Concurrently, it is important to develop methods to produce robust photon sources. In this context, semiconductor quantum dots hold great potential, due to their exceptional photophysical properties and on-demand operating nature. Concerning the scalability aspect of semiconductor quantum dots, it is advantageous to develop a simple, yet robust method to generate photon states from it. Chirped pulse excitation has been widely demonstrated as a robust and efficient state preparation scheme in quantum dots, thereby boosting its applicability as a stable photon source in a real-world scenario. Despite the rapid growth and advancements in laser technologies, the generation and control of chirped laser pulses can be demanding. Here, an overview of a selected few approaches is presented to tailor and characterize chirped pulses for the efficient excitation of a quantum dot source. By taking the chirped-pulse-induced adiabatic rapid passage process in quantum dot as an example, numerical design examples are presented along with experimental advantages and challenges in each method and conclude with an outlook on future perspectives.
    University Bibliography Jena:
    fsu_mods_00009894External link

  6. Unlocking Extreme Parallelization: 1 kW Ultrafast Laser Processing with Compensation of Spatio-Temporal Effects for Large Angle Beam Splitting

    Year of publicationPublished in:2025 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) D. Mekle, D. Grossmann, B. Dannecker, H. Höck, D. Bauer, D. Flamm, S. Nolte
    University Bibliography Jena:
    fsu_mods_00027669External link

  9. Spectral and dispersion tuning of fiber Bragg gratings by tailored femtosecond laser refractive index modification

    Year of publication T. Imogore
    In this thesis, novel inscription techniques for tailoring the spectral and dispersive properties of an FBG using ultrashort laser pulses are developed and investigated. These inscription techniques do not only rely on the variation of the grating period along the grating length but combine the functionalities of the phase mask inscription technique and direct inscription techniques to incorporate flexibility and reproducibility in tailoring the average refractive index profile of an FBG before (pre-processing), during and after inscription (post-processing). Also, this work explores the application of these techniques in tailoring the spectral and dispersive properties of an inscribed FBG and in realizing complex FBGs in both silica and flouride fibers.
    University Bibliography Jena:
    fsu_mods_00028792External link

  10. Avoiding the tip: spiral optics for robust high power beam shaping of Bessel beams

    Year of publicationPublished in:Optics Express M. Siems, J. Thomas, H. Gross, A. Schöneberg, S. Nolte
    Bessel Gaussian beams offer unique possibilities in material processing due to their elongated high-intensity line foci. They are usually created using an axicon. Being used with high power, the most critical part of the axicon is its tip, as it is prone to laser-induced damage. Any imperfection of the tip can be the source of aberrations of the focus. Therefore, we propose to apply Laguerre Gaussian beam shaping to circumvent the tip of the axicon altogether. We introduce an optical system consisting of spiral phase plates and an axicon to combine Laguerre and Bessel Gaussian beam shaping. This system is experimentally implemented using custom-made spiral phase plates and a large angle axicon. We characterize and finally apply the system to glass cutting and demonstrate the cleaving of a 2 mm thick glass sample, which results in a high-quality breaking edge with sub-micron roughness.
    University Bibliography Jena:
    fsu_mods_00023856External link
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