The use of hollow-core photonic crystal fibers in operando spectrometry of chemical reactions is a relatively unexplored technology. It can be used in different ways and offers a variety of advantages compared with conventional operando spectrometry, such as a significantly increased path length with a simultaneously reduced volume. We apply fiber absorption spectroscopy here to the synthesis of gold nanoparticles. We measured the rate of formation of gold nanoparticles at different initial concentrations. We show that much higher resolution is possible with this technique in comparison with a conventional measurement technique using cuvettes.
A 25 THz bandwidth THz spectroscopy system exploiting BNA crystals and a tunable single-ring-fiber pulse compressor
Wei Cui,
Aswin Vishnuradhan,
Markus Lippl,
Eeswar Kumar Yalavarthi,
Angela Gamouras,
Nicolas Joly,
Jean-Michel Ménard
We present a terahertz time-domain spectroscopy (THz-TDS) system which accesses a broadband spectrum, efficiently covering the so-called "new THz gap" between 5 and 15 THz and extending beyond 25 THz. The system exploits nonlinear interactions within the organic crystal BNA (N-benzyl-2-methyl-4-nitroaniline) to generate and detect THz radiation upon excitation by a near-infrared (NIR) pulse centered at 1.03 um. To enable broadband THz spectral monitoring, the NIR pulse from a Yb-based solid-state laser undergoes spectral broadening in a gas-filled single-ring hollow-core photonic crystal fiber, followed by pulse compression to achieve durations as short as 31 fs. This approach paves the way for broadband spectroscopy in hard-to-access THz regions using widely available near-infrared ultrafast sources.
Twisted single-ring hollow-core fiber for broadband chiral detection in nanoliter volumes
Christof Helfrich,
Sonia Maniappan,
Michael Frosz,
Raju Adhikary,
Sandro Colagioia,
Nicolas Joly,
Andrea Marini,
Francesco Tani
Journal of Physics: Photonics
8
015035
(2026)
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The ongoing evolution of hollow-core fibers continues to inspire the development of optofluidic platforms with enhanced sensitivity and minimal sample requirements. Here, we utilize the intrinsic advantages of anti-resonant reflection hollow-core fibers—such as low optical loss and broadband transmission—to realize a twisted single-ring hollow-core fiber (SR-HCF) tailored for polarization-sensitive chiral detection. We optimize the fiber geometry to ensure single-mode operation by strongly attenuating higher-order modes (>50 dB/m) while maintaining low loss for the fundamental mode (<0.1 dB/m) and reducing the sample volume to only ~660 nanoliters per 34 cm fiber length. By applying a constant twist along the fiber length, we minimize birefringence and ensure stable transmission of linear polarization states with polarization extinction ratios (PER) surpassing 38 dB. After injecting an aqueous solution of an optically active molecule, we measure its optical rotation (OR) at different wavelengths with millidegree-level sensitivity and remarkable robustness against misalignment. Measurements with different enantiomeric excess concentrations are in good agreement with independent liquid chromatography characterization.
Soliton self-frequency shift in hollow-core fiber for bright femtosecond radiation tunable across the short-wavelength infrared
Markus Lippl,
Martin Butryn,
Nicolas Joly,
Francesco Tani
We report a fiber-based source of femtosecond radiation that is spectrally tunable in the short-wavelength infrared region, delivering average powers at the multi-watt level. The system utilizes self-soliton frequency shifting in a hydrogen-filled hollow-core fiber, producing pulse trains at 1.1 MHz with integrated relative intensity noise below 0.3% and a polarization extinction ratio of 30 dB. This source constitutes an efficient and valid fiber-based alternative to optical parametric amplifiers for a variety of applications, including THz generation, multiphoton imaging, and high-harmonic generation.
Scientific career
Since 2021: Head of the microstructured optical fibres independent research group at the Max-Planck Institute for the Science of Light in Erlangen, Germany
Since 2009: Associate professor at the Univ. of Erlangen-Nuremberg in Germany
2005 – 2008: Maître de conférences at the Univ. of Lille in France
Education background
2012: Habilitation at the Ecole Normale Supérieure of Cachan (France) Title: Supercontinuum generation using pulses propagating in photonic crystal fibres, Defended in July. 10th 2012. Thesis adviser: Prof. Dr. Joseph Zyss.
2002-2005: Post-doctoral fellow at the University of Bath (UK) in the group of Prof. Philip Russell
1999-2002: PhD with honors (“Félicitations du jury”) at the laboratory of Physics of Lasers, Atoms, and Molecules (PhLAM) at the University of Lille (France) Title: Instabilities in pulsed mode-locked lasers: techniques for observation and control Defended on Sept. 23rd 2002. Thesis adviser: Prof. Dr. Serge Bielawski.
Awards & appointments
Since 2023: Advisor of the Erlangen Optica Student Chapter
Since 2021: Scientific coordinator of the Internation Max Planck School for the Physics of Light (IMPRS-PL)
Since 2020: Senior member of Optical Society of America (OSA)
Since 2019: Fellow of the Max Planck School of Photonics (MPSP) and member of the selection committee
Since 2016: Fellow of the Max Planck Center for Extreme and Quantum Photonics, Ottawa, Canada
1999: MENRT scholarship from the French ministry of Research to perform his doctoral degree at the University of Lille from 1999 to 2002
1998: Awarded a CIME scholarship from AUF (Agence universitaire de la Francophonie) to perform his Master study at Laval University (Québec) in 1998
Professional activities
2024: Member of the Technical Program Committee for the SPIE Photonics Europe in Strasbourg
Since 2022: Associate Editor of Opt. Express
2017: General chair of the 1st Sino-German symposium on fiber photonics for light-matter interaction in Shanghai, China
2017 – 2018: Member of the Technical Program Committee for SPIE UV and higher energy photonic
2013 – 2017: Member of Technical Program Committee for CLEO US (OSA)
2015: co-Chair of the 2nd Siegman International School of Laser (OSA)
Since 2015: Member of the Technical Program Committee for WSOF (OSA) in Hong-Kong (2015), Limasol in Cypris (2017), Adelaide in Australia (2022), and in Prague in Czech Republic (2025)
Since 20214: Member of the Student Commission of the internation Master of Advanced Optics and Technologies (MAOT)
2013: Topical session at PIERS (Progress in Electromagnetics Research Symposium) in Stockholm
2011: International conference on Nonlinear optics and complexity in photonic crystal fibers and nanostructures in Erice, in Sicily
2011: 14th International SAOT workshop on Fiber laser, sensors and materials at Reicheschwand, Germany
Since 2009: External expert for the evaluation of proposals from ANR (National agency of research in France), the Polish Society of Science, DFG (National agency of research in Germany) and ERC (European Research Council)
Since 2009: Supervisor of 13 PhD students, 2 post-docs, 14 MSc students
Ongoing projects
DFG project JO 1090/8-3 – OrbitFlySens [FAU] Orbiting flying particle sensor (with Bernhard Schmauß, FAU) – 2025-2028
BayFrance FK-34-2024 [FAU] Real-time detection of Terahertz signals using ultrashort lasers Mobility allowance – collaboration with University of Lille - 2025
BayFrance FK-35-2024 [FAU] Exploring chiral fibers for new-type of polarization-resolved endoscopy Mobility allowance – collaboration with University of Marseille – 2025
DFG project JO 1090/3-2 – Photon Triplets [FAU] Generation of photon triplets via three-photon parametric down-conversion (with Maria Chekhova) – 2024-2027
QuNet beta [MPL] 2021-2026
Max-Planck-School of Photonics (MPSP) [FAU] 2019-2025
DFG project JO 1090/6-1 -Twin Beams [FAU] Fiber source of entangled photons with giant tunable frequency separation (with Maria Chekhova) - 2021-2024
DFG project JO 1090/4-1 – Rydbergatoms in photonic crystal fibres [FAU] (with Robert Löw, University of Stuttgart) - 2019-2023
BayFrance FK-29-2018 [FAU] Frequency conversion of single-photon quantum sources using gas-filled hollow-core photonic crystal fibres Mobility allowance – collaboration with LKB, Ens Paris, France - 2018
DFG project JO 1090/3-1 – Photon Triplets [FAU] Generation of photon triplets via three-photon parametric down-conversion (with Maria Chekhova) – 2017-2020
BayFrance FK-38-2013 [FAU] Dynamical instabilities in photonic crystal fiber ring cavities synchronously pumped by femtosecond pulses Mobility allowance – collaboration with University of Lille, France - 2013-2014
