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- ItemGiant faraday rotation through ultra-small Fe0n clusters in superparamagnetic FeO-SiO2 vitreous films(Hoboken : Wiley, 2017) Nakatsuka, Yuko; Pollok, Kilian; Wieduwilt, Torsten; Langenhorst, Falko; Schmidt, Markus A.; Fujita, Koji; Murai, Shunsuke; Tanaka, Katsuhisa; Wondraczek, LotharMagnetooptical (MO) glasses and, in particular, Faraday rotators are becoming key components in lasers and optical information processing, light switching, coding, filtering, and sensing. The common design of such Faraday rotator materials follows a simple path: high Faraday rotation is achieved by maximizing the concentration of paramagnetic ion species in a given matrix material. However, this approach has reached its limits in terms of MO performance; hence, glass‐based materials can presently not be used efficiently in thin film MO applications. Here, a novel strategy which overcomes this limitation is demonstrated. Using vitreous films of xFeO·(100 − x)SiO2, unusually large Faraday rotation has been obtained, beating the performance of any other glassy material by up to two orders of magnitude. It is shown that this is due to the incorporation of small, ferromagnetic clusters of atomic iron which are generated in line during laser deposition and rapid condensation of the thin film, generating superparamagnetism. The size of these clusters underbids the present record of metallic Fe incorporation and experimental verification in glass matrices.
- ItemAdvanced fiber in-coupling through nanoprinted axially symmetric structures(New York, NY : AIP, 2023) Yermakov, Oleh; Zeisberger, Matthias; Schneidewind, Henrik; Kim, Jisoo; Bogdanov, Andrey; Kivshar, Yuri; Schmidt, Markus A.Here, we introduce and demonstrate nanoprinted all-dielectric nanostructures located on fiber end faces as a novel concept for the efficient coupling of light into optical fibers, especially at multiple incidence angles and across large angular intervals. Taking advantage of the unique properties of the nanoprinting technology, such as flexibly varying the width, height, and gap distance of each individual element, we realize different polymeric axial-symmetric structures, such as double-pitch gratings and aperiodic arrays, placed on the facet of commercial step-index fibers. Of particular note is the aperiodic geometry, enabling an unprecedentedly high average coupling efficiency across the entire angular range up to 80°, outperforming regular gratings and especially bare fibers by orders of magnitude. The excellent agreement between simulation and experiment clearly demonstrates the quality of the fabricated structures and the high accuracy of the nanoprinting process. Our approach enables realizing highly integrated and ready-to-use fiber devices, defining a new class of compact, flexible, and practically relevant all-fiber devices beyond the state-of-art. Applications can be found in a variety of cutting-edge fields that require highly efficient light collection over selected angular intervals, such as endoscopy or quantum technologies. Furthermore, fiber functionalization through nanoprinting represents a promising approach for interfacing highly complex functional photonic structures with optical fibers.
- ItemPublisher Correction: Coherent interaction of atoms with a beam of light confined in a light cage(London : Nature Publishing Group, 2021) Davidson-Marquis, Flavie; Gargiulo, Julian; Gómez-López, Esteban; Jang, Bumjoon; Kroh, Tim; Müller, Chris; Ziegler, Mario; Maier, Stefan A.; Kübler, Harald; Schmidt, Markus A.; Benson, Oliver[no abstract available: correction of https://doi.org/10.1038/s41377-021-00556-z published online 31 May 2021; After publication of this article, it is noticed the article contained an error. In Table 1, the data in the line ‘Length (mm)’ is missing. The complete Table 1 is provided in this correction.]
- ItemNanograting-Enhanced Optical Fibers for Visible and Infrared Light Collection at Large Input Angles(Basel : MDPI, 2021) Wang, Ning; Zeisberger, Matthias; Hübner, Uwe; Schmidt, Markus A.The efficient incoupling of light into particular fibers at large angles is essential for a multitude of applications; however, this is difficult to achieve with commonly used fibers due to low numerical aperture. Here, we demonstrate that commonly used optical fibers functionalized with arrays of metallic nanodots show substantially improved large-angle light-collection performances at multiple wavelengths. In particular, we show that at visible wavelengths, higher diffraction orders contribute significantly to the light-coupling efficiency, independent of the incident polarization, with a dominant excitation of the fundamental mode. The experimental observation is confirmed by an analytical model, which directly suggests further improvement in incoupling efficiency through the use of powerful nanostructures such as metasurface or dielectric gratings. Therefore, our concept paves the way for high-performance fiber-based optical devices and is particularly relevant within the context of endoscopic-type applications in life science and light collection within quantum technology.
- ItemUltrafast intermodal third harmonic generation in a liquid core step-index fiber filled with C2Cl4: erratum(Washington, DC : Soc., 2021) Schaarschmidt, Kay; Kobelke, Jens; Nolte, Stefan; Meyer, Tobias; Schmidt, Markus A.We provide a correction due to an erroneous repetition rate of one of the laser systems (90 fs pulse duration) in our previously published paper [Opt. Express28, 25037 (2020)10.1364/OE.399771].
- ItemSupercontinuum generation in a carbon disulfide core microstructured optical fiber(Washington, DC : Soc., 2021) Junaid, Saher; Bierlich, Joerg; Hartung, Alexander; Meyer, Tobias; Chemnitz, Mario; Schmidt, Markus A.We demonstrate supercontinuum generation in a liquid-core microstructured optical fiber using carbon disulfide as the core material. The fiber provides a specific dispersion landscape with a zero-dispersion wavelength approaching the telecommunication domain where the corresponding capillary-type counterpart shows unsuitable dispersion properties for soliton fission. The experiments were conducted using two pump lasers with different pulse duration (30 fs and 90 fs) giving rise to different non-instantaneous contributions of carbon disulfide in each case. The presented results demonstrate an extraordinary high conversion efficiency from pump to soliton and to dispersive wave, overall defining a platform that enables studying the impact of non-instantaneous responses on ultrafast soliton dynamics and coherence using straightforward pump lasers and diagnostics.
- ItemResonance-Induced Dispersion Tuning for Tailoring Nonsolitonic Radiation via Nanofilms in Exposed Core Fibers(Weinheim : Wiley VCH, 2020) Lühder, Tilman A.K.; Schaarschmidt, Kay; Goerke, Sebastian; Schartner, Erik P.; Ebendorff-Heidepriem, Heike; Schmidt, Markus A.Efficient supercontinuum generation demands for fine-tuning of the dispersion of the underlying waveguide. Resonances introduced into waveguide systems can substantially improve nonlinear dynamics in ultrafast supercontinuum generation via modal hybridization and formation of avoided crossings. Using the example of exposed core fibers functionalized by nanofilms with sub-nanometer precision both zero-dispersion and dispersive wave emission wavelengths are shifted by 227 and 300 nm, respectively, at tuning slopes higher than 20 nm/nm. The presented concept relies on dispersion management via induced resonances and can be straightforwardly extended to other deposition techniques and film geometries such as multilayers or 2D materials. It allows for the creation of unique dispersion landscapes, thus tailoring nonlinear dynamics and emission wavelengths and for making otherwise unsuitable waveguides relevant for ultrafast nonlinear photonics. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemNumerical and Experimental Demonstration of Intermodal Dispersive Wave Generation(Weinheim : Wiley VCH, 2021) Lüpken, Niklas M.; Timmerkamp, Maximilian; Scheibinger, Ramona; Schaarschmidt, Kay; Schmidt, Markus A.; Boller, Klaus‐J.; Fallnich, CarstenEvidence of intermodal dispersive wave generation mediated by intermodal cross-phase modulation (iXPM) between different transverse modes during supercontinuum generation in silicon nitride waveguides is presented. The formation of a higher-order soliton in one strong transverse mode leads to phase modulation of a second, weak transverse mode by iXPM. The phase modulation enables not only supercontinuum generation but also dispersive wave generation within the weak mode, that otherwise has insufficient power to facilitate dispersive wave formation. The nonlinear frequency conversion scheme presented here suggests phase-matching conditions beyond what is currently known, which can be exploited for extending the spectral bandwidth within supercontinuum generation.
- ItemCoherent interaction of atoms with a beam of light confined in a light cage(London : Nature Publishing Group, 2021) Davidson-Marquis, Flavie; Gargiulo, Julian; Gómez-López, Esteban; Jang, Bumjoon; Kroh, Tim; Müller, Chris; Ziegler, Mario; Maier, Stefan A.; Kübler, Harald; Schmidt, Markus A.; Benson, OliverControlling coherent interaction between optical fields and quantum systems in scalable, integrated platforms is essential for quantum technologies. Miniaturised, warm alkali-vapour cells integrated with on-chip photonic devices represent an attractive system, in particular for delay or storage of a single-photon quantum state. Hollow-core fibres or planar waveguides are widely used to confine light over long distances enhancing light-matter interaction in atomic-vapour cells. However, they suffer from inefficient filling times, enhanced dephasing for atoms near the surfaces, and limited light-matter overlap. We report here on the observation of modified electromagnetically induced transparency for a non-diffractive beam of light in an on-chip, laterally-accessible hollow-core light cage. Atomic layer deposition of an alumina nanofilm onto the light-cage structure was utilised to precisely tune the high-transmission spectral region of the light-cage mode to the operation wavelength of the atomic transition, while additionally protecting the polymer against the corrosive alkali vapour. The experiments show strong, coherent light-matter coupling over lengths substantially exceeding the Rayleigh range. Additionally, the stable non-degrading performance and extreme versatility of the light cage provide an excellent basis for a manifold of quantum-storage and quantum-nonlinear applications, highlighting it as a compelling candidate for all-on-chip, integrable, low-cost, vapour-based photon delay.
- ItemInterfacing optical fibers with plasmonic nanoconcentrators(Berlin : de Gruyter, 2018) Tuniz, Alessandro; Schmidt, Markus A.The concentration of light to deep-subwavelength dimensions plays a key role in nanophotonics and has the potential to bring major breakthroughs in fields demanding to understand and initiate interaction on nanoscale dimensions, including molecular disease diagnostics, DNA sequencing, single nanoparticle manipulation and characterization, and semiconductor inspection. Although planar metallic nanostructures provide a pathway to nanoconcentration of electromagnetic fields, the delivery/collection of light to/from such plasmonic nanostructures is often inefficient, narrow-band, and requires complicated excitations schemes, limiting widespread applications. Moreover, planar photonic devices reveal a reduced flexibility in terms of bringing the probe light to the sample. An ideal photonic-plasmonic device should combine (i) a high spatial resolution at the nanometre level beyond to what is state-of-the-art in near-field microscopy with (ii) flexible optical fibers to promote a straightforward integration into current near-field scanning microscopes. Here, we review the recent development and main achievements of nanoconcentrators interfacing optical fibers at their end-faces that reach entirely monolithic designs, including campanile probes, gold-coated fiber-taper nanotips, and fiber-integrated gold nanowires.