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This PDF file contains the front matter associated with SPIE Proceedings Volume 11676, including the Title Page, Copyright information, and Table of Contents.
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A fully stabilized optical frequency comb provides equally spaced frequencies for a precise ruler in optical frequency metrology. This talk will review recent progress in dual-comb generation from diode pumped solid-state and vertical emitting semiconductor lasers. In dual-comb modelocked operation, the initially unpolarized beam is split with an intracavity birefringent crystal. A mode-locked integrated external-cavity surface-emitting laser (MIXSEL) integrates both the gain and the saturable absorber layer within the same semiconductor wafer which simplifies the laser geometry to a linear straight cavity with excellent noise performance. A dual-comb gigahertz optically pumped MIXSEL has been used for molecular spectroscopy and lidar applications without the need of any additional stabilization. More recently a dual-comb diode-pumped Yb:CaF2 laser has been demonstrated at 140 MHz. For lidar applications we compare both lasers demonstrating micron precision over a potential ambiguity range of multi-kilometers and multi-kilohertz update rates.
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Biomedical Applications for Ultrafast Laser Systems
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Nowadays Er:YAG lasers are employed for bone surgery because of their emission wavelengths of 2.94µm which allows for optimization of material removal rate. Nevertheless, high degrees of tissue carbonization are unavoidable and prevent the process of tissue regeneration. In this work, a femtosecond source with a pulse duration of 350fs was employed to carry a comparative study on ablation efficiency and quality at wavelengths of 1030nm and 515nm. Laser-treated bones were analyzed by optical profilometry, SEM and EDX. Results show that on optimization of the process parameters is necessary to achieve an optimal quality of ablation without tissue carbonization.
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Ultrashort laser pulses can be used to achieve remarkable precision during surgical ablation. Thus far, the clinical potential of ultrafast laser microsurgery has barely begun to be realized, with clinical adoption limited to ophthalmic applications. One of the technological barriers to the adoption of this technology is the lack of a means to flexibly deliver the laser light to clinical sites in or on the patient. The goal of this talk is to provide an overview on the current state of clinical ultrafast laser surgery development in our lab and describe its potential use in 2 clinical applications.
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Multi-photon Polymerization for 3D Microstructuring
3D micro-printing or direct laser writing is the method of choice for fabricating intricate three-dimensional micro- and nanostructures. Employing ultrafast lasers to drive non-linear absorption allows precise structuring of polymeric as well as metallic materials, enabling applications from bio-inspired research up to precise metrology. In this presentation I will give an overview over our current developments on direct metal printing and novel approaches towards structures employed in artificial gauge-field optics allowing to switch topological protection on and off. Additionally, applications in optical metrology will be discussed.
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Industrial High Precision 3D Lithography via Two-Photon Absorption (TPA) is a potential disruptive tool for microfabrication that enables novel products for diverse applications in the field of optics, photonics, biomedicine, and life sciences. A customized therapeutic approach to develop bone cartilage transplants for patients with arthrosis by means of TPA is presented. These implants consist of scaffolds as extracellular matrices (ECM) that mimic natural tissue and serve as physical and bioactive support for the generation of autologous tissue capable of replacing or repairing damaged tissue. The variable TPA technology with adjustable precision and structure dimension is the key to a defined micro structuring that enables hierarchically 3D micro structured monolithic biphasic scaffolds for the therapy of bone cartilage damage on an industrial scale.
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Two-photon polymerization (2PP) is a direct laser writing technology that enables the fabrication of fully 3D structures with sub-diffraction limit resolution. The mechanical properties of structures fabricated by 2PP are strongly dependent on the irradiation parameters. In this respect, here we perform a systematic characterization of the elastic properties of SZ2080, a hybrid organic/inorganic negative sol-gel photoresist, by combining dynamic experimental tests and numerical simulations on properly designed micro-cantilevers. The knowledge acquired in this characterization will be exploited in the fabrication of complex 3D metamaterials.
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Industrial Applications for Ultrafast Laser Systems
Laser ablation in burst mode enables operation close to the optimum pulse fluence of the material thus maximizing the ablation efficiency and reducing the heat affected zone. In addition, burst mode operation can enhance the ablation rate in some materials due to thermal interaction between burst pulses via the material. We have measured ablation rates for burst mode ablation on various materials (metals, semiconductors, dielectrics) as a function of pulse fluence, intra-burst repetition rate (60 MHz, 180 MHz, 360 MHz, 720 MHz, 1.44 GHz) and the number of pulses per burst (1-30), using a 40 μJ, 1035 nm Yb:Fiber MOPA with 300 fs pulse duration and repetition rates between 100 kHz and 250 kHz. The ablated geometries were rectangular cavities with side lengths of about 0.3 mm times 2 mm. The ablation efficiencies in burst mode operation are compared with the efficiencies that can be obtained with single pulse operation at high repetition rates and the same pulse fluence. Depending on material, number of pulses in the burst, intra-burst repetition rate and the ablation geometry, the ablation efficiency can be equal, lower or multiple times higher as compared to non-burst operation.
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We report on a 100-fs GHz burst laser with up to 100-W average output power. This laser is based on a Tangor femtosecond laser with GHz burst option followed by nonlinear pulse compression in a gas-filled hollow core Kagomé fiber. Combining pulse compression with hollow core fiber transport is an attractive extension for industrial femtosecond lasers. Laser ablation of metals, silicon, and sapphire have been performed with this new laser source in order to study the impact of the ultrashort pulse duration on the laser matter interaction with GHz bursts.
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We present a spectral phase measurement and correction method utilizing a pulse shaper. Positive and negative π/2 spectral phase steps are scanned across the spectrum of the pulse while collecting second harmonic spectra. Second and third order phase distortions show characteristic features in the difference between the spectra. Computer simulations show the amplitude and sign of these features quantitatively determine the magnitude and sign of the second and third order dispersion with milliradian accuracy. Experimental dispersion measurements are benchmarked by measuring the group velocity dispersion of air as well as fused silica windows.
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We report on the first industrial UV femtosecond laser with more than 100W average output power. The laser is ideally suited for high throughput precision applications, in particular for glass and polymer cutting in display industry. Thanks to its flexibility in pulse repetition rate, pulse energy, and free triggering at constant pulse energy, the femtosecond UV laser can be used in parallel processing with multiple beams as well as in high speed scanning applications, e.g. with polygonal scanners. The femtosecond pulse duration after frequency conversion to UV can be substantially reduced compared to the 400-fs pulse duration high power laser at the fundamental wavelength of 1030nm.
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We present a CEO-stable 1.1 kW CPA system that is designed to drive a few-cycle-generation stage (<6fs pulse duration) and a subsequent atto-second beamline at the ELI-ALPS facility in Szeged. It currently delivers >300W of average power at 100kHz repetition-rate providing <10fs pulses. The chirped-pulse-amplification system (CPA) demonstrates excellent noise properties with <220mrad of the integrated carrier-envelope-offset (CEO) noise (10Hz to 20MHz) at a pulse repetition rate of 80MHz while the relative-intensity-noise (RIN) stayed <0.3%. This is the first CEO-stable laser system at 1kW level average power.
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We report on a kilowatt femtosecond laser with the high precision triggering function FemtoTrig® and flexible burst shapes. The high power femtosecond laser is based on a multi-stage hybrid fiber-crystal based Innoslab amplifier platform and chirped pulse amplification. The kilowatt femtosecond laser is foreseen to serve in high throughput applications integrating multiple beams generated by diffractive optical elements (DOEs) and allowing individual pulse control of the multiplexed beamlets via multi-channel acousto-optical modulators.
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We present a monolithic fiber optic configuration for generating temporally coherent supercontinuum (SC) pulsed emission with the shortest pulse duration presented to date, to our knowledge, by an all-fiber source. Few-cycle pulses as short as 14.8 fs are obtained, with central emission wavelength of 1060 nm, repetition rate of 75 MHz and average power of 250 mW. The SC generation is obtained by pumping an all-normal dispersion (ANDi) photonic crystal fiber (PCF) with a mode-locked Yb fiber laser. Spectral broadening by self-phase modulation preserves compressible pulses in the temporal domain. Compared to previously reported configurations exploiting ANDi PCFs, all stages of our source are fiber based and fiber coupled between them. Avoidance of free-space propagation between stages confers unequalled robustness, efficiency and cost-effectiveness to this novel configuration. The ANDi PCF was designed and produced to provide a convex, flat-top dispersion curve with group velocity dispersion comprised between -20 and 0 ps/nm/km in the wavelength range from 900 to 1200 nm. A d-scan system was designed and built to compress and characterize the pulses. The spectrum, wider than 150 nm, supports a Fourier limit pulse duration of 13.7 fs, and pulses have been actually compressed down to 14.8 fs, which demonstrates a high level of temporal coherence in the achieved supercontinuum; second- and third-order dispersion of the pulses are measured as low as -145 fs2 and 875 fs3, respectively. The source has been integrated in a twophoton fluorescence and second-harmonic generation microscopy setup, where 3D images of biological samples have been successfully obtained.
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We present the first high-power coherently combined thulium-doped fiber-CPA. The laser system delivers >228 µJ pulse energy with <120 fs pulse duration at a pulse repetition frequency of 500 kHz. Excellent long-term stability is achieved with an average power fluctuation of <0.5% RMS over >48 hours of operation even at an average-power >120 W. The simultaneous availability of 100 W class average power and 1 GW-class peak power in the 2 µm wavelength regime is not only unique in the world of science but also comes in a fully engineered and commercially available system design optimized for long-term operation..
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The lasers and conventional optics used in charged-particle beam x-ray free electron laser photo-injectors are designed using fundamentally the same techniques for decades. We present a novel method for the generation and conditioning of the UV laser used for electron generation via photoemission that can enhance electron beam and X-ray performance. Additionally, we discuss laser-based spatio-temporal shaping and conditioning of electron beam phase space in order to selectively promote lasing operational modes.
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Ultrashort pulsed laser has been expected to be a powerful and reliable tool for micro-welding of glass. Picosecond pulsed laser with high pulse repetition rate leads to melting of glass at the vicinity of focal region by the heat accumulation, in which the absorption point of laser energy moves periodically in beam axis. Thus, the control of focusing situation in beam axis is very important to investigate the mechanical strength of weld part. In the microwelding of borosilicate glass by picosecond pulsed laser of 1064 nm, characteristics of molten area creation and weld joint were discussed. Numerical aperture (N.A.) greatly affects characteristics of molten area formation, and superior focusing characteristics, such as N.A. 0.65 enable a long region of high power density in beam axis, which can create a large molten area without cracks even under high energy condition. An appropriately large molten area inside glass has high mechanical strength, when continuous and large molten areas were formed. In addition, high density and large size of molten area without crack led to increasing Young’s modulus, and uniform and high Young’s modulus of molten area results in higher breaking stress.
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We demonstrated the fabrication of gold microstructures inside a PEG-based hydrogel with different charged fluorophores by multi-photon photoreduction. By adding an anionic charged FITC-dextran or a cationic charged Rhodamine110 to the metal ion solution, line width of the fabricated gold microstructures increased compared to that of the structures fabricated in fluorophore-free hydrogel. The photobleaching could enhanced the reduction of gold ions accompanying the oxidation of the fluorophores. Notably, the inhibition of reduction of gold ions at a site other than the focal point was observed with FITC-dextran, which may be attributable to the coordination of gold ions to FITC-dextran.
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The demand for greater link capacity in datacenters has pushed silicon photonic (SiP) optical interconnects from linear edge coupler arrays to two-dimensional grids of vertical grating couplers. To meet the challenge for low-profile, fiber-to-chip coupling, 3D optical waveguide circuits were integrated with total internal reflection (TIR) mirrors, enabling efficient horizontal fiber coupling and vertical SiP coupling through a fused silica interposer. TIR air disks of 30 µm diameter and ~3 µm thickness were fabricated up to 320 µm circuit depth by femtosecond laser irradiation followed by chemical etching (FLICE). The micro-mirror offered 0.54 to 1.2 dB reflection loss for waveguide-to-waveguide coupling within the interposer, as measured across the 1460 to 1625 nm telecom bands. The efficient TIR mirror lays the groundwork for flexible design of 3D photonic interposers to meet high-density interconnection requirements of SiP circuits to multicore fiber arrays for the telecom industry.
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In this talk, we will demonstrate a couple of examples on microfluidic glass chip and implantable device exploiting femtosecond laser-based fabrication. Firstly, an implantable blood pressure sensor packaged by direct laser welding is demonstrated. The sealing quality of the implantable sensors using direct laser welding is compared with the other sensor produced by conventional fabrication method. Secondly, we proposed a novel glass microfluidic chip including a passive micromixer with an impeller which is fabricated in a fused silica. The mixing efficiency up to 99% and the maximum throughput of 30 mL/min was measured.
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We report on the separation of complex inner and outer contours from glass articles with curved surfaces using ultrashort pulsed lasers. To achieve single-pass, full-thickness modifications along the entire substrate a processing optics is presented that allows for beam shaping of non-diffracting beams and, additionally, for aberration compensation of phase distortions occurring at the curved interface. The glass articles finally separated by thermal stress or via selective laser etching meet the demands of the medical industry in terms of micro-debris, surface quality and processing speed.
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Femtosecond laser light has been shaped with a spatial light modulator (SLM) to generate optically thin, aberration-free sheets of uniform intensity for inscription of fiber Bragg gratings (FBGs) inside the core of SMF-28 telecommunication fiber. The combination of flexible beam shaping and sheet-by-sheet writing offers facile means in controlling the coupling to cladding or radiation modes while facilitating spectral tuning flexibility that is not available with interference-based techniques. Spectral responses of uniform first order FBGs fabricated with single-pulse exposures are presented.
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A two-dimensional (2D), point-by-point writing technique of forming filament arrays with femtosecond laser pulses was applied inside of single-mode optical fiber to open new opportunities for 2D photonic bandgap engineering and highresolution spectroscopy. A small grating period of ~300 nm provided first-order diffraction externally to the fiber cladding, with spectral, blazing, and self-focusing properties tailored by varying the 1D and 2D grating design. The spectral properties of the lens-less, all-fiber spectrometer have been tuned with varying grating dimension, chirping rate, and blazing design that can meet wide ranging criteria for design of compact grating spectrometers in narrow to broad spectral ranges of the visible and telecommunication bands.
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Ultrafast pump-probe imaging requires both an accurate synchronization of probe pulses with the pump and that the probe pulses are free from spatio-temporal distortions. However, characterizing weak probes inside transparent solids reveals to be particularly difficult. We report a new in-situ diagnostic for ultrashort probes using a micrometric-sized Kerr-based transient grating induced in the sample by a shaped pump pulse. Our configuration allows us to synchronize pump and probe pulses in-situ, to measure the ultrashort probe pulse duration, and to remove pulse front tilt of the weak probe. Our approach is valid for any probe wavelength and polarization.
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Ultrafast laser welding is a fast, clean, and contactless technique for joining a broad range of materials. Nevertheless, this technique cannot be applied for bonding semiconductors and metals. By investigating the nonlinear propagation of picosecond laser pulses in silicon, it is elucidated how the evolution of filaments during propagation prevents the energy deposition at the semiconductor–metal interface. While the restrictions imposed by nonlinear propagation effects in semiconductors usually inhibit countless applications, the possibility to perform semiconductor–metal ultrafast laser welding is demonstrated. This technique relies on the determination and the precompensation of the nonlinear focal shift for relocating filaments and thus optimizing the energy deposition at the interface between the materials. The resulting welds show remarkable shear joining strengths (up to 2.2 MPa) compatible with applications in microelectronics. Material analyses shed light on the physical mechanisms involved during the interaction.
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Gold nanoparticles have attracted attention of researchers due to certain unique features like biocompatibility, stability during bioconjugation with other metals or semiconductor materials, expression of surface plasmon resonance phenomenon etc. In the current work, we subject laser ablation produced gold nanoparticles to the study of optical nonlinearities by employing 120 fs, 84 MHz ultrafast laser pulses at 800 nm wavelength. After confirmation of particle size and shape is carried out by Transmission Electron Microscopy, the optical nonlinear absorption and refraction parameters are measured via the popular Z-scan technique. Excitation intensity is varied from 6.23 GW/cm2 upto 23.37 GW/cm2 for open aperture measurements and from 3.39 GW/cm2 to 23.37 GW/cm2 for closed aperture measurements. The open aperture results show significant nonlinear absorption effect through an initial two-photon absorption and a subsequent multi-photon absorption phenomenon. The transition from saturable absorption to reverse saturable absorption takes place at an excitation threshold of 17.14 GW/cm2. The closed aperture measurements depict a fairly symmetric response upto an excitation intensity of 15.58 GW/cm2 after which asymmetry initiates. This could be possibly due to the dominance of nonlinear absorption over nonlinear refraction. The coefficients of nonlinear absorption and nonlinear refraction are in the range of 10-3 cm/GW and 10-5 cm/GW respectively. An understanding of these optical nonlinearities enhances their application for biomedical diagnostics, and optical switching and limiting.
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Pulsed laser ablation in liquids (LAL) is a growing field for the generation of metallic nanoparticles, but a comprehensive picture of the fundamental mechanisms is still missing. The process is always associated with rapid material ejection, shock waves and cavitation. Time-resolved photography with speckle-free illumination at exposure times below 200 ps can “freeze” these events and provide diffraction-limited resolution. We present a novel light source fulfilling these demands based on a SBS compressed Q-switched laser pulse pumping a dye cell and illustrate it’s utility through photography of LAL events on a gold target.
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By considering intra-band electron oscillations driven by intense few-cycle laser pulses, we show feasibility of generation of femtosecond photocurrent pulses in non-metal solids without external bias by laser pulses carrying as many as 15 cycles. The physical mechanism of the photocurrent is attributed to non-zero cycle-averaged momentum of the oscillating electrons produced by violation of sub-cycle symmetry of momentum departures. Reported analytical model delivers scaling of peak photocurrent (total charge) with material and laser parameters including carrier-envelope phase. We discuss applications of this novel ultrafast electro-optic effect in temporal shaping of ultrashort pulses and novel regimes of material processing.
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Low loss optical waveguides are the key component for the fabrication of more complex integrated optics devices. In most works related to femtosecond laser written waveguides, the values presented give results at a single wavelength or in a narrow wavelength band; but some applications in optical sensing, for example, would benefit from waveguides having good propagation properties in a larger wavelength range. This paper presents results that allow one to gain insight into the major loss mechanisms present in laser written waveguides in two different types of glasses (fused silica and Eagle 2000 glass) and the dependence of those on the fabrication parameters. Finally, an example of application of broadband operating waveguides is given.
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Satellite-based optical quantum technologies represent a promising field for obtaining a worldwide quantum network. However, due to the limited size of satellites and the adverse conditions of a space environment, only compact and resistant devices can be used for this purpose. In this respect, we present for the first time the space qualification of integrated photonic circuits fabricated by Ultrafast Laser Writing. By inscribing different straight waveguides, directional couplers and Mach-Zehnder interferometer, and by exposing them to appropriate proton and gamma ray irradiations, we show that our integrated devices are suited for performing quantum experiments in a low Earth orbit.
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Volume Bragg Gratings (VBG) are inscribed in the bulk of non-conventional photosensitive glasses tailored with silver by means of femtosecond laser irradiation. Thanks to intrinsic features of the spatial distribution of silver-sustained inscribed structures, it is possible to fabricate gratings with sub-wavelength periodic refractive index modulation. As a result, the achieved VBG target first-order Bragg reflection in the VIS - NIR spectral range. This work paves the way to manufacturing more complex optical devices, such as Waveguide Bragg Gratings.
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Femtosecond laser welding was extended to optical silica fiber (SMF-28) by focusing through fused silica substrates and ferrules to form all-glass weld seams. Laser radiation was focused into the fiber cladding to create a welding zone, which drove molten glass to fill as much as a 3 𝜇𝑚 gap around a contact line to form a crack free pseudo-continuous welding seams along the contact line. The strong weld seams up to 30 𝜇𝑚 wide were generated in fiber-to-plate and fiber-to-ferrule geometries without inducing photochemical or thermal degradation of a fiber Bragg grating (FBG) positioned only 62.5 𝜇m from the weld zone. Welding was optimized by real-time monitoring of the FBG thermo-optical shift during laser scanning. Four-point bending tests confirmed a high mechanical strength while thermal annealing showed stable mechanical and FBG responses up to 1000 ˚C. Femtosecond laser writing and welding thus demonstrated a flexible means for photonics fabrication and packaging of FBGs, enabling reliable, high frequency vibration sensing suited for high temperature and strain environments.
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Femtosecond laser writing (FLW) has been recognized as a powerful technique to engineer various materials to realize a number of applications. Dielectric crystals with periodically lattice structures play significant roles for optical and photonic applications. By efficient modification of refractive indices of the dielectrics, optical waveguides with diverse configurations have been produced by FLW. In addition to the well-known parameters of the laser writing system, e.g., pulse energy, scanning speed, and repetition rate, it has also been found that the modification of refractive index strongly depends on the symmetry of the specific crystals, i.e., the crystal system of the lattices. The laser-induced track morphology engineering is crucial to not only tailor the properties of waveguides but also for applications in novel photonic device fabrication. The mode modulation has been therefore implemented by selecting appropriate fabrication conditions according to crystals with different lattice symmetries. Regardless of the complexity of crystal refractive index changes induced by ultrafast pulses, several three-dimensional (3D) geometries have been designed and implemented, which are useful for 3D fabrication of laser written photonic chips. This work gives an overview of the recent advances on the laser-written crystalline waveguides, indicating attractive potential applications in various areas of photonics.
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An electron that multiphoton ionizes is immediately subject to the light’s electric field that will control its short-term future. This control enables a gas of atoms to produce intense VUV or soft X-ray beams. Since we can precisely control the infrared beam, we can synthesize attosecond soft X-ray pulses – pulses that are the shortest controlled events ever systematically produced. For complex atom (such as xenon), the recollision electron shares its energy in any multi-electron interaction. Measuring the energy share encodes multielectron dynamics such as the Fano resonance structure in helium and the Giant Plasmon resonance in Xenon.
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In recent years coherent diffraction imaging (CDI) has evolved into a mature technology. Thanks to its lensless nature, it allowed to bypass the limitations of X-ray optics. At the same time, laser development in combination with high harmonic generation (HHG) has pushed the coherent XUV photon flux to values comparable to 3rd generation synchrotron facilities, which enables lensless imaging experiments that were previously only possible at large-scale facilities. Furthermore, the intrinsic short pulse duration of HHG radiation has potential for imaging experiments down to attosecond time scales. In this contribution, we present our latest results on lensless imaging using a fiber laser driven HHG source at 92 eV. A high photon flux source is used for scanning coherent diffractive imaging (ptychography) demonstrating sub-50 nm resolution. Further, an extension to Fourier transform holography is shown, which enables to increase the useable bandwidth by a factor of five without sacrificing spatial resolution. This paves the way for combing high-resolution table-top lensless imaging with attosecond pump-probe experiments.
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High harmonic generation at high repetition rate is realized with a high average power 100W, 600kHz fiber laser system. Optimization is done for two different operation regimes. At 69-75eV the source delivers a world-record photon flux of >10^11photons/s/harmonic when using argon gas jets. The use of neon gas allows for operation at significantly shorter wavelength. The important 93eV harmonic can be generated at 5·10^9 photons/s/(1% bandwidth), while even higher values of >10^10 photons/s/(1% bandwidth) are achieved between 115-140eV. The HHG source provides excellent long-term power stability of ~1% RMS for each of the operation regimes.
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Intense, ultrafast laser sources with an operation wavelength beyond the well-established near-IR are valuable tools for exploiting the wavelength scaling laws of strong-field, light-matter interactions. Such laser systems enable the scaling of the phase matching photon energy cut-off in high-order harmonic generation, which allows for the generation of coherent soft X-ray radiation up to, and even beyond, the water window. Such laser-driven sources enable a plethora of subsequent applications. A number of these applications can significantly benefit from an increase in repetition rate. In that regard, ultrafast thulium-doped fiber laser systems (providing a broad amplification bandwidth in the 2 μm wavelength region) represent a promising, average-power scalable laser concept for driving high-order harmonic generation. These lasers are capable of delivering ~100 fs pulses with multi-GW peak power at hundreds of kHz repetition rate. In this work, we show that combining ultrafast thulium-doped fiber CPA systems with HHG in an antiresonant hollow-core fiber is a promising approach to realize high photon energy cut-off HHG from a compact setup. The realization is based on combining nonlinear pulse self-compression (leading to strong-field waveforms) and phase-matched high-order harmonic generation in a single antiresonant hollow-core fiber. In this demonstration, a photon energy cut-off of approximately 330 eV has been achieved, together with a photon flux >106 ph/s/eV at 300 eV. These results emphasize the great potential of exploiting the HHG wavelength scaling laws with 2 μm fiber laser technology. Improvements of the HHG efficiency, the overall HHG yield and further laser performance enhancements will be the subjects of our future work.
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Electrochemical biosensors are increasingly used for the detection of various analytes (pesticides, mycotoxins etc.) in food, due to the rapid and reliable detection that can be achieved without the need for expensive instrumentation equipment, skilled personnel and long time-to–result that is required by conventional analytical techniques. Laser Induced Forward Transfer (LIFT) bio-printing in combination with an all- in- one enzyme solution (a solution that includes the enzyme mixed with signal-enhancing carbon-based materials suspended in a polymer matrix) provides new possibilities for biosensor pesticide detection in olive oil as it delivers direct and accurate immobilization of enzyme solution with high special resolution and the ability to print in significantly smaller electrode surfaces for less material waste. Here, we report the use of LIFT technique, utilizing a 355 nanosecond laser for the highly precise, direct deposition and immobilization of Acetylcholinesterase (AChE) on screen printed electrode (SPE) surfaces. Due to the high impact pressure of the transferred droplets at the receiver substrate, the physical adsorption of the enzyme mixture onto the surface is enhanced, improving the electrochemical communication with the SPE. The inhibitory effect of the analytes on the AChE biosensor was evaluated amperometrically by determining the decrease in the current obtained for the oxidation of the thiocholine produced by the enzyme upon incubation with pesticide solutions, and a LoD below the legislation limit (10 ppb) was achieved. Furthermore, the biosensor’s performance was assessed in olive oil samples spiked with carbofuran and chlorpyrifos, following an optimized pretreatment protocol, with very satisfactory recovery values.
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