Article
Optics
Benjamin Maingot, Elizaveta Neradovskaia, Cyrille Claudet, Nicolas Forget, Aurelie Jullien
Summary: The nonlinear refractive indices (n(2)) of various bulk and liquid crystals were measured at 1030 nm using nonlinear chirped interferometry with a sub-picosecond regime. These measurements provide crucial parameters for designing near- to mid-infrared parametric sources and all-optical delay lines.
Article
Optics
Vikas Remesh, Ria G. Kraemer, Rene Schwarz, Florian Kappe, Yusuf Karli, Malte Per Siems, Thomas K. Bracht, Saimon Filipe Covre da Silva, Armando Rastelli, Doris E. Reiter, Daniel Richter, Stefan Nolte, Gregor Weihs
Summary: A scalable source of single photons is crucial for efficient quantum photonic architecture. Semiconductor quantum dots have great potential for this purpose, and a compact and efficient method for chirped pulse excitation is proposed using chirped fiber Bragg gratings.
Article
Multidisciplinary Sciences
Dong Mao, Huaqiang Wang, Heze Zhang, Chao Zeng, Yueqing Du, Zhiwen He, Zhipei Sun, Jianlin Zhao
Summary: By engineering the intracavity group delay, mode-locked solitons at different wavelengths can be synchronized inside the laser cavity. Frequency-resolved measurements fully retrieve the fine temporal structure of pulses, validating the direct generation of synchronized ultrafast lasers from multiple wavelengths.
NATURE COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Ruiyi Chen, Yanzhi Wang, Jianda Shao, Yu Cao, Yuhui Zhang, Zhihao Wang, Yuchuan Shao, Yunxia Jin, Kui Yi, Jiabing Hu, Yi Xu, Yuxing Leng, Ruxin Li
Summary: This study presents the concept of high-damage-threshold chirped mirrors (HDTCMs) for ultrafast high-power laser systems, and introduces a novel design method to achieve both high reflectivity and high laser-induced damage threshold (LIDT) over a broad bandwidth. The proposed HDTCM design effectively enhances LIDT by manipulating the electric field distribution of laser pulses. As a proof of concept, an HDTCM is designed and achieves a significant increase in LIDT.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2022)
Article
Optics
Neil A. Macleod, Peter G. Huggard, Manju Henry, Damien Weidmann
Summary: The demonstration and evaluation of chirped laser dispersion spectroscopy (CLaDS) for quantitative measurements of gas molecules with broad spectral features is reported. This technique shows promising value in sensing turbid media with variations, owing to its immunity to changes in received optical power.
Article
Optics
Peihong Li, Yu Wang, Xin Liu, Qing Bai, Baoquan Jin
Summary: This paper proposes a synchronous cascade scheme using random number modulation to enhance the signal-to-noise ratio (SNR) in phase-sensitive optical time-domain reflectometry (tp-OTDR) systems. The scheme utilizes random number codes to obtain SNR gain and investigates the effects of pulse extinction ratio and rising edge on coding gain. Theoretical simulation and experimental results demonstrate improved pulse extinction ratio, shortened rising edge, and enhanced coding gain, leading to increased SNR.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Engineering, Chemical
Sara Marchini, Andre Bieberle, Markus Schubert, Uwe Hampel
Summary: This paper introduces the application of gas flow modulation technique (GFM) in measuring the axial gas dispersion coefficient in bubble columns. By providing systematic guidelines for selecting experimental parameters, the limitations of traditional tracer-based techniques are overcome, and a novel approach for extracting the values and uncertainty limits of the gas dispersion coefficient is proposed. The application of these guidelines is demonstrated through a case study, illustrating their practicality and usefulness.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Optics
Ji Wang, Yunlin Chen, Kun Zhao, Zhiyi Wei
Summary: Ultrafast petawatt laser facilities require pulse compression strategies to deal with high-order dispersions, with special compensation techniques needed for third-order and fourth-order dispersions. Quasiparametric amplification (QPA) is efficient and can act as a high-efficiency nonlinear phase compensator. The study discusses the high-order dispersions in QPA and their impact on amplified signal pulses.
Article
Engineering, Chemical
Sara Marchini, Andre Bieberle, Eckhard Schleicher, Markus Schubert, Uwe Hampel
Summary: The gas flow modulation technique (GFM) is a recently proposed method for measuring the axial gas dispersion coefficient in bubble columns. It utilizes a time-resolved measurement of modulated gas holdup at different axial positions in the column to calculate the dispersion coefficient. Gamma-ray densitometry has been used in recent studies for holdup measurement due to its accuracy, but it presents logistical and safety challenges in industrial settings. This study explores nonradiative measurement techniques such as differential pressure sensors, conductivity needle probes, and optical probes as alternatives to gamma-ray densitometry, with the differential pressure sensors proving to be a particularly viable alternative.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Physics, Multidisciplinary
Zhang Peng, Teng Hao, Yang Hao, Lu Ren-Chong, Wang Ke-Jian, Zhu Jiang-Feng, Wei Zhi-Yi
Summary: We report a femtosecond chirped-pulse amplification (CPA) system based on block material stretcher and grism compression, which can achieve shorter compressed pulses. By amplifying the stretched pulses with a regenerative amplifier and optimizing the design of the grism compressor, complete compensation of material dispersion is achieved, resulting in compressed pulses close to the limit. The system simplifies the structure, reduces the space size, and improves the operational stability of the laser system.
ACTA PHYSICA SINICA
(2022)
Article
Optics
Yuzhuo Wang, Yizun He, Lingjing Ji, Jiangyong Hu, Xing Huang, Yudi Ma, Liyang Qiu, Kaifeng Zhao, Saijun Wu
Summary: The method utilizes a fiber electro-optical modulator to transfer microwave signals to light signals, and achieves amplification and balancing of the light signals through a tapered semiconductor amplifier, thus suppressing noise generation. This method can be applied to wideband optical control of atoms and molecules.
CHINESE OPTICS LETTERS
(2022)
Article
Optics
Vladimir Ya Molchanov, Konstantin B. Yushkov, Pavel Kostryukov, Petr B. Gornostaev, Nikolay S. Vorobiev
Summary: This study in the field of ultrafast optics experimentally investigated acousto-optic pulse shaping and found that the sign of the second order dispersion from the acousto-optic dispersion delay line impacts modulation rise/fall time. By comparing different algorithms, the researchers achieved a minimum modulation rise/fall time for 3mJ pulses with linear chirp at 6.2 ps/nm at a wavelength of 795nm.
OPTICS AND LASER TECHNOLOGY
(2021)
Article
Chemistry, Multidisciplinary
Dongjun Zhang, Ping Zhu, Xinglong Xie, Yan Liang, Qingwei Yang, Meizhi Sun, Xiao Liang, Jun Kang, Haidong Zhu, Ailin Guo, Qi Gao, Youjian Yi, Linjun Li, Cheng Liu, Jianqiang Zhu
Summary: The study focused on a single-shot method to directly measure the temporal contrast enhancement of a single plasma mirror, achieving a contrast enhancement of 10(2) in a hundred picosecond timescale. The method did not degrade the performance of the plasma mirror, making it a promising approach for single-shot online diagnosis of plasma mirrors.
APPLIED SCIENCES-BASEL
(2021)
Article
Automation & Control Systems
Zhaojing Wu
Summary: This paper investigates the pulse width modulation (PWM) control for Lagrange systems driven by servo motors in a stochastic environment. The principles of PWM for stochastic nonlinear systems are proven, and a continuous control bounded in probability of the stochastic Lagrange system is designed. A stochastic closed-loop nonlinear programming is modeled in the same form as that in the deterministic case. The effectiveness of the proposed scheme is demonstrated by a simulation of articulated manipulator.
Article
Multidisciplinary Sciences
Asami Honda, Keisaku Yamane, Kohei Iwasa, Kazuhiko Oka, Yasunori Toda, Ryuji Morita
Summary: Ultrafast beam pattern modulation can be achieved by superimposing chirped optical vortex pulses with orthogonal spatial modes. This technique allows for stable and robust modulations with high intensity and can be applied to spatially coherent excitation and collective excitation.
SCIENTIFIC REPORTS
(2022)
Article
Optics
Arno Klenke, Albrecht Steinkopff, Christopher Aleshire, Cesar Jauregui, Stefan Kuhn, Johannes Nold, Christian Hupel, Sigrun Hein, Steffen Schulze, Nicoletta Haarlammert, Thomas Schreiber, Andreas Tuennermann, Jens Limpert
Summary: In this paper, a coherently combined femtosecond fiber chirped-pulse-amplification system based on a multicore fiber is presented, which demonstrates excellent performance in terms of high power and pulse energy. The system is scalable by increasing the number of cores in the fiber.
Article
Optics
Steffen Haedrich, Evgeny Shestaev, Maxim Tschernajew, Fabian Stutzki, Nico Walther, Florian Just, Marco Kienel, Imre Seres, Peter Jojart, Zsolt Bengery, Barnabas Gilicze, Zoltan Varallyay, Adam Borzsonyi, Michael Mueller, Christian Grebing, Arno Klenke, Dominik Hoff, Gerhard G. Paulus, Tino Eidam, Jens Limpert
Summary: A two-stage multipass-cell compression technique is used to compress a fiber-chirped pulse amplifier system to the few-cycle regime. The system achieves a sub-2-cycle output with excellent beam quality, pointing stability, and long-term average power stability. It also exhibits good carrier-envelope phase stability in a wide frequency range.
Article
Materials Science, Multidisciplinary
Paul Schmitt, Nadja Felde, Thorsten Dohring, Manfred Stollenwerk, Ingo Uschmann, Kevin Hanemann, Marie Siegler, Georg Klemm, Nancy Gratzke, Andreas Tunnermann, Stefan Schwinde, Sven Schroder, Adriana Szeghalmi
Summary: Metallic coatings, especially iridium, are crucial for infrared optical systems due to their high reflectivity and thermal stability. The properties of iridium coatings deposited by atomic layer deposition (ALD) and magnetron sputtering (MS) differ due to their different topography and microstructure.
OPTICAL MATERIALS EXPRESS
(2022)
Article
Optics
Albrecht Steinkopff, Christopher Aleshire, Arno Klenke, Cesar Jauregui, Jens Limpert
Summary: In this work, different approaches to counteract the performance limitations induced by thermal effects in coherently-combined, multicore fiber amplifiers are presented. Pumping MCFs in co-propagation improves combinable average power, while a new MCF design pumped in counter-propagation reduces thermal load and allows for high combined output power and pulse energy.
Article
Optics
Anne-Sophie Munser, Marcus Trost, Sven Schroeder, Martina Graf, Miriam A. Rosenbaum, Andreas Tuennermann
Summary: Due to its high sensitivity and quick measurement principle, angle-resolved scattering (ARS) measurements show promising potential as a rapid analysis tool for bacterial cells, especially at small sample sizes and low cell numbers. This study has demonstrated that scattered light from various bacterial cell samples can be analyzed at the single-cell level, which is a significant benefit compared to time-consuming conventional methods that require hours or days of cellular growth. With the proposed setup and data analysis method, it is possible to detect scatter differences among cell types as well as measure cell concentration.
Article
Optics
Alexander Kirsche, Martin Gebhardt, Robert Klas, Lucas Eisenbach, Wilhelm Eschen, Joachim Buldt, Henning Stark, Jan Rothhardt, Jens Limpert
Summary: In this work, a continuously tunable extreme ultraviolet (XUV) source with a high photon flux spanning from 50 eV to 70 eV is presented. The setup includes a high-power fiber laser, a multipass cell, and a waveguide-based high harmonic generation setup. Tuning of the XUV spectrum is achieved by adjusting the laser's driving pulse energy and utilizing nonlinear propagation effects and pulse chirping. The method allows for high tuning speed and delivers reproducible and reliable results. A method for continuous, on-demand pulse-to-pulse switching of the generated XUV radiation with full spectral coverage is also proposed for future experiments.
Article
Optics
Maximilian Karst, Pauline Pfaller, Robert Klas, Ziyao Wang, Philipp Gierschke, Jan Rothhardt, Jens Limpert
Summary: This study presents the use of a gas-filled multipass cell to compress 515 nm wavelength second-harmonic pulses from a Yb:fiber laser from 240 fs to 15.7 fs. The system delivers 0.44 mJ of pulse energy, 22.4 W of average power at 50.8 kHz with an overall efficiency of more than 40%. These results demonstrate the capability of multipass-cell-based post-compression schemes to shift from the established near infrared region to the unexplored visible regime, enabling high efficiency generation of energetic ultrashort pulses at high repetition rates. The unique combination of parameters in the green spectral range offers immense potential for future development of high photon flux higher-order harmonic sources.
Article
Optics
Chang Liu, Wilhelm Eschen, Lars Loetgering, Daniel Penagos S. Molina, Robert Klas, Alexander Iliou, Michael Steinert, Sebastian Herkersdorf, Alexander Kirsche, Thomas Pertsch, Falk Hillmann, Jens Limpert, Jan Rothhardt
Summary: Table-top extreme ultraviolet (EUV) microscopy provides new possibilities for studying biological samples without using labels. In this study, we demonstrate ptychographic EUV imaging of dried, unstained model specimens, such as germlings of a fungus and bacteria cells, at a wavelength of 13.5 nm. By using a position-correlated ptychography approach, we achieve a millimeter-squared field of view with sub-60 nm spatial resolution, enabling the identification of nanoscale material composition inside the specimens. This work will advance EUV imaging applications and open up new possibilities in life science research.
Proceedings Paper
Optics
Cesar Jauregui, Sobhy Kholaif, Yiming Tu, Jens Limpert
Summary: In this work, the prediction of static modal energy transfer in polarization-maintaining fibers is presented, which can serve as an early warning system for TMI and provide valuable insights into the physics behind it.
FIBER LASERS XIX: TECHNOLOGY AND SYSTEMS
(2022)
Proceedings Paper
Optics
Sobhy Kholaif, Cesar Jauregui, Yiming Tu, Jens Limpert
Summary: Mitigation strategies of transverse mode instability are usually based on reducing the strength of the thermally induced refractive index grating and/or the modal interference pattern, or manipulating the phase shift through heat load modulation. This can achieve beam cleaning and improve the performance of the amplifier system.
FIBER LASERS XIX: TECHNOLOGY AND SYSTEMS
(2022)
Proceedings Paper
Optics
Arno Klenke, A. Steinkopff, C. Aleshire, C. Jauregui, Stefan Kuhn, Johannes Nold, Christian Hupel, Sigrun Hein, Steffen Schulze, Nicoletta Haarlammert, Thomas Schreiber, Andreas Tuennermann, Jens Limpert
Summary: In this paper, a rod-type, Ytterbium-doped, multicore fiber with 4x4 cores is presented. This fiber is used in a CPA setup for coherent beam combination of femtosecond pulses. High average powers of up to 507 W after combination and compression are achieved at 10 MHz repetition rate. A high combination efficiency of 85% is realized together with excellent beam quality. Additionally, up to 600 µJ pulse energy is measured in a lower repetition rate configuration.
FIBER LASERS XIX: TECHNOLOGY AND SYSTEMS
(2022)
Proceedings Paper
Optics
Henning Stark, Christian Grebing, Joachim Buldt, Michael Mueller, Arno Klenke, Jens Limpert
Summary: Yb:fiber-based pulses are split and recombined to achieve high peak power and pulse energy output, while avoiding laser-induced damage. The system demonstrates good efficiency, beam quality, and temporal contrast.
FIBER LASERS XIX: TECHNOLOGY AND SYSTEMS
(2022)
Proceedings Paper
Optics
Yiming Tu, Cesar Jauregui, Sobhy E. Kholaif, Jens Limpert
Summary: Modal decomposition (MD) techniques are used to characterize the modal amplitudes and phases of eigenmodes in optical fibers. This work presents a high-speed, real-time modal decomposition method of fiber laser beams using a spatial mode multiplexer (MUX). The MUX functions as a demultiplexer and allows the modal amplitude information to be obtained by reading out different single-mode fiber (SMF) input ports. The method has been proven to be accurate and extremely fast, even capable of decomposing the beam during a Q-switched pulse emission and producing real-time results.
FIBER LASERS XIX: TECHNOLOGY AND SYSTEMS
(2022)
