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Several journals
Image: Ira Winkler, IAP (University Jena)

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Highlighted authors are members of the University of Jena.

  2. 117-mJ pulse energy, high average power, Q-switched Yb-doped 49-core fiber amplifier

    Year of publicationPublished in:Optics Express M. Bahri, C. Jauregui, A. Klenke, M. Lenski, J. Nold, N. Haarlammert, T. Schreiber, J. Limpert
    This work presents the simultaneous scaling of the average power and pulse energy emitted by multicore fiber laser systems. This is achieved through two series of experiments that use a generation of Yb-doped multicore fiber amplifiers with 49 cores, seeded by a Q-switched multicore fiber laser. One of the main results of these experiments is a total pulse energy of up to 117 mJ at a repetition rate of 5 kHz in quasi-continuous pumping operation. In a different experiment with a smaller core size multicore fiber, an average power of 400 W was achieved at a repetition rate of 5 kHz, corresponding to a pulse energy of 80 mJ in continuous pumping. The experimental results match our simulation predictions, providing valuable insights into the further energy scalability of Yb-doped multicore fibers.
    University Bibliography Jena:
    fsu_mods_00030210External link

  3. Polarization-maintaining, rod-type, ytterbium-doped, multi-core fiber for high power operation

    Year of publicationPublished in:Optics Express Y. Khalil, C. Jauregui, A. Klenke, M. Bahri, J. Nold, N. Haarlammert, T. Schreiber, J. Limpert
    It has been previously observed that each core in a multi-core fiber has its own birefringence properties. Therefore, obtaining a laser output with a well-defined polarization pattern from a multi-core fiber is challenging. In this work, we explain the origin of this core-dependent birefringence and present a polarization-maintaining, 35-core fiber design that is tested in an oscillator setup, delivering over 100W of power with a polarization contrast ratio close to 10dB. This is a significant improvement with respect to a comparable non-polarization-maintaining multi-core fiber.
    University Bibliography Jena:
    fsu_mods_00030211External link

  4. Recent developments in the understanding and passive mitigation of transverse mode instability

    Year of publicationPublished in:Optical Fiber Technology: Materials, Devices, and Systems C. Jauregui, Y. Tu, S. Kholaif, F. Möller, G. Palma-Vega, N. Haarlammert, T. Walbaum, T. Schreiber, J. Limpert
    In this article we look at the newest developments in the understanding and mitigation of TMI in single-core fibers. This includes recent quantitative measurements that reveal the dependence of the TMI threshold on the modal content of the seed, systematic measurements on the dependence of the TMI threshold on the fiber core size, as well as the study of TMI in PM fibers including a novel passive mitigation strategy and the static modal energy transfer recently observed in these fibers.
    University Bibliography Jena:
    fsu_mods_00029154External link

  7. Extreme optical nonlinearities unveiled by ultrafast laser filamentation in semiconductors

    Year of publicationPublished in:Nature Communications M. Chambonneau, M. Blothe, V. Fedorov, I. de Kernier, S. Tzortzakis, S. Nolte
    Sky-high optical nonlinearities make semiconductors ideal platforms for multifunctional photonic devices. The fabrication of such complex devices could greatly benefit from in-volume ultrafast laser writing for monolithic and contactless integration. Ironically, as exemplified for Si, nonlinearities act as an efficient immune system that self-protects the material from internal permanent modifications. Predicting high-intensity ultrashort-pulse propagation beyond Si is further limited by incomplete descriptions of carrier dynamics in narrow-gap materials. Here, we demonstrate that filamentation universally dictates ultrashort laser pulse propagation in various semiconductors. The effective key nonlinear parameters extracted differ markedly from past measurements with low-intensity pulses, while temporal scaling laws for these parameters are also derived. Based on these findings, appropriate temporal-spectral shaping is proposed for tailored energy deposition inside semiconductors. The effective parameters also provide predictive inputs for semiconductor backside processing, microelectronics security, and high-harmonic, supercontinuum and terahertz wave generation.
    University Bibliography Jena:
    fsu_mods_00034334External link

  8. Broadband Bright Biphotons From Periodically Poled Brillouin Zone Folding Metasurface

    Year of publicationPublished in:Laser and Photonics Reviews J. Zhang, C. Shi, J. Ma, F. Setzpfandt, T. Pertsch, C. Bao, J. Zhang, A. Sukhorukov
    University Bibliography Jena:
    fsu_mods_00029702External link

  9. Inverse microparticle design for enhanced optical trapping and detection efficiency in all six degrees of freedom

    Year of publicationStatusReview pendingPublished in:JPhys Photonics M. Lee, B. Stickler, T. Pertsch, S. Hong
    Achieving quantum-limited motional control of optically trapped particles beyond the sub-micrometer scale is an outstanding problem in levitated optomechanics. A key obstacle is solving the light scattering problem and identifying particle geometries that allow stable trapping and efficient motional detection of their center of mass and rotational motion in three dimensions. Here, we present a computational framework that combines an efficient electromagnetic scattering solver with the adjoint method to inversely design printable microparticles tailored for levitated optomechanics. Our method allows identifying optimized geometries, characterized by enhanced optical trapping and detection efficiencies compared to conventional microspheres. This improves the feasibility of quantum-limited motional control of all translational and rotational degrees of freedom in a standard standing-wave optical trap.
    University Bibliography Jena:
    fsu_mods_00030334External link

  10. Bridging Classical and Quantum Approaches for Quantitative Sensing of Turbid Media with Polarization-Entangled Photons

    Year of publicationPublished in:Laser and Photonics Reviews V. Besaga, I. Lopushenko, O. Sieryi, A. Bykov, F. Setzpfandt, I. Meglinski
    Polarimetry with quantum light promises improved measurements for various scenarios. However, fundamental understanding of quantum photonic state transport in complex, real media, and tools to interpret the state after interaction with the sample are still lacking. Here, we theoretically and experimentally explore the evolution of polarization-entangled states in a turbid medium on example of tissue phantoms. By elaborating mathematical relationship between Wolf's coherency matrix and density matrix, we introduce a versatile framework describing the transfer of entangled photons in turbid environments with polarization tracking and resulting quantum state representation with the density operator. Experimentally, we reveal a robust trend in the state evolution depending on the reduced scattering coefficient of the medium. Our theoretical predictions correlate with experimental findings, while the model extends the study by photonic states with different degrees of entanglement. The presented results pave the way for quantitative quantum photonic sensing enabling applications ranging from biomedical diagnostics to remote sensing.
    University Bibliography Jena:
    fsu_mods_00029724External link

  11. Thickness Dependence of Linear and Nonlinear Optical Properties of Multilayer 3R‐MoS 2

    Year of publicationStatusReview pendingPublished in:Advanced Optical Materials F. Abtahi, A. Shaji, G. Ngo, B. Laudert, H. Esfandiar, S. Schmitt, F. Eilenberger
    3R-MoS ₂ , a MoS ₂ polytype with broken inversion symmetry, enables unique light-matter interactions and is promising for linear and nonlinear integrated photonics beyond the monolayer limit. Yet, systematic studies of its thickness-dependent reflectivity and its impact on harmonic generation are still lacking. While AFM can offer atomic-scale resolution, measuring 3R-MoS ₂ on non-solid substrates like PDMS remains challenging. To address this, a fast, non-destructive optical method is introduced to determine the thickness of 3R-MoS ₂ flakes from reflectivity measurements with a mean bias of less than 2 nm in the 3–200 nm range. Nonlinear characterization further reveals distinct thickness-dependent maxima in second- and third-harmonic generation (SHG/THG), with the first clear peak at ≈200 nm. These maxima arise from Fabry–Pérot-type phase matching conditions mediated by the film thickness and can further be shaped by absorption. This work thus provides both a practical thickness metrology and new insights for exploiting thickness-dependent 3R-MoS ₂ nonlinearities in scalable photonic technologies.
    University Bibliography Jena:
    fsu_mods_00030234External link

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

    Year of publicationPublished 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
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