Femtosecond laser systems
Industrial femtosecond lasers
Model | Repetition rate | Pulse duration | Max pulse energy | Special feature |
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FemtoLux 50 | 2 MHz | 350 fs – 1 ps | 300 µJ | |
FemtoLux 30 | 4 MHz | 400 fs – 1 ps | 1 mJ | |
FemtoLux 3 | 10 MHz | 300 fs – 5 ps | 3 µJ |
Model | Repetition rate | Pulse duration | Max pulse energy | Special feature |
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Publications
Comparative analysis of microlens array formation in fused silica glass by laser: Femtosecond versus picosecond pulses
The growing demand for flexible, high-quality fabrication of free-form micro-optics drives the development of laser-based fabrication techniques for both the shape formation and surface polishing of optical elements. In this paper, we performed a thorough and systematic study on fused silica glass ablation using 10 ps and 320 fs duration pulses. Ablation processes for both pulse durations were optimized based on the measurements of the removed material layer thickness and surface roughness, and by analyzing the topographies of ablated cavities to remove material layers as thin as possible with minimum surface damage. Our findings demonstrate higher process resolution and surface quality for femtosecond pulses. Ablation of pre-roughened glass reduced the minimal removable glass layer thickness well below the 1 μm mark for both pulse durations, improving the process resolution. The minimal removable glass layer thickness was 14 times smaller for the femtosecond pulses, with up to 4.5 times lower surface roughness compared to samples processed with picosecond pulses. On the other hand, results revealed faster glass removal rates with picosecond pulses. In the end, arrays of microlenses were fabricated with both pulse durations and subsequently polished with a CO2 laser. Results revealed higher performance of microlenses fabricated with femtosecond pulses, providing better focusing capabilities and lesser beam scattering. Finally, this study demonstrated the successful fabrication of free-form optical elements with femtosecond and picosecond pulses, demonstrating the versatility and the potential of laser-based techniques.
The ultrafast burst laser ablation of metals: Speed and quality come together
Utilisation of high-power ultrafast laser for ablation-based industrial processes such as milling, drilling or cutting requires high production rates and superior quality. In this paper, we demonstrate highly efficient, rapid and high-quality laser micro-machining of three industrial metals (aluminium, copper, and stainless steel). Our proposed optimisation methods of pulse energy division in time result in simultaneous enhancement of ablation efficiency (volume per energy) and ablation rate (volume per time) while maintaining a focused laser beam on the target surface and high resolution. A high-tech femtosecond burst laser, producing laser pulses of τ = 350 fs duration and intra-burst repetition rates of fP = 50 MHz, was employed in the experiments. Due to the utilisation of bursts, material removal efficiency and removal rate were increased by 18.0 %, 44.5 %, and 37.0 % for aluminium, copper, and stainless steel if compared with the best performance of single-pulses. In addition to the high processing rate, processing by burst mode resulted in lower surface roughness. This technique is believed to be a solution enabling extremely high femtosecond laser powers for precise microfabrication.
Ultrashort Pulse Bursts for Surface Laser Polishing
Laser polishing offers numerous advantages, one of which is the convenience of using the same system for the
whole manufacturing process. In this work, an ultrashort pulse laser operating in a GHz burst regime was used to polish
stainless steel. The aim was to minimise surface roughness, characterised by the average roughness parameter Ra. Different
laser processing parameters (average laser power, number of pulses per burst, scanning speed, hatch size) were varied to polish
samples that were covered in laser-induced periodic surface structures (LIPSS). Thermal effects, such as melt layer formation,
were noticed and discussed. It was demonstrated that LIPSS can be erased and the initial surface roughness of 73 nm was
reduced to 41 nm using 100 pulses per burst and burst fluence of FB = 0.15 J/cm2.
Acoustic resonance effects and cavitation in SAW aerosol generation
The interaction of surface acoustic waves (SAWs) with liquids enables the production of aerosols with adjustable droplet sizes in the micrometer range expelled from a very compact source. Understanding the nonlinear acousto-hydrodynamics of SAWs with a regulated micro-scale liquid film is essential for acousto-microfluidics platforms, particularly aerosol generators. In this study, we demonstrate the presence of micro-cavitation in an MHz-frequency SAW aerosol generation platform, which is touted as a leap in aerosol technology with versatile application fields including biomolecule inhalation therapy, micro-chromatography and spectroscopy, olfactory displays, and material deposition. Using analysis methods with high temporal and spatial resolution, we demonstrate that SAWs stabilize spatially arranged liquid micro-domes atop the generator’s surface. Our experiments show that these liquid domes become acoustic resonators with highly fluctuating pressure amplitudes that can even nucleate cavitation bubbles, as supported by analytical modeling. The observed fragmentation of liquid domes indicates the participation of three droplet generation mechanisms, including cavitation and capillary-wave instabilities. During aerosol generation, the cavitation bubbles contribute to the ejection of droplets from the liquid domes and also explain observed microstructural damage patterns on the chip surface eventually caused by cavitation-based erosion.
Characterization of pathological stomach tissue using polarization-sensitive second harmonic generation microscopy
Alterations in collagen ultrastructure between human gastric adenocarcinoma and normal gastric tissue were investigated using polarization-resolved second harmonic generation (PSHG) microscopy. Cylindrical and trigonal symmetries were assumed to extract quantitative PSHG parameters, ρ, κ and S, from each image pixel. Statistically significant variations in these values were observed for gastric adenocarcinoma, indicating a higher disorder of collagen. Numerical focal volume simulations of crossing fibrils indicate increased S parameter is due to more intersecting collagen fibrils of varying diameters. These parameters were also able to distinguish between different grades of gastric adenocarcinoma indicating that PSHG may be useful for automated cancer diagnosis.
Clean production and characterization of nanobubbles using laser energy deposition
We have demonstrated the production of laser bulk nanobubbles (BNB) with ambient radii typically below 500 nm. The gaseous nature of the nanometric objects was confirmed by a focused acoustic pulse that expands the gas cavities to a size that can be visualized with optical microscopy. The BNBs were produced on demand by a collimated high-energy laser pulse in a “clean” way, meaning that no solid particles or drops were introduced in the sample by the generation method. This is a clear advantage relative to the other standard BNB production techniques. Accordingly, the role of nanometric particles in laser bubble production is discussed. The characteristics of the nanobubbles were evaluated with two alternative methods. The first one measures the response of the BNBs to acoustic pulses of increasing amplitude to estimate their rest radius through the calculation of the dynamics Blake threshold. The second one is based on the bubble dissolution dynamics and the correlation of the bubble’s lifetime with its initial size. The high reproducibility of the present system in combination with automated data acquisition and analysis constitutes a sound tool for studying the effects of the liquid and gas properties on the stability of the BNBs solution.
Femtosecond Laser Cutting of 110–550 µm Thickness Borosilicate Glass in Ambient Air and Water
The cutting quality and strength of strips cut with femtosecond-duration pulses were investigated for different thicknesses of borosilicate glass plates. The laser pulse duration was 350 fs, and cutting was performed in two environments: ambient air and water. When cutting in water, a thin flowing layer of water was formed at the front surface of the glass plate by spraying water mist next to a laser ablation zone. The energy of pulses greatly exceeded the critical self-focusing threshold in water, creating conditions favorable for laser beam filament formation. Laser cutting parameters were individually optimized for different glass thicknesses (110–550 µm). The results revealed that laser cutting of borosilicate glass in water is favorable for thicker glass (300–550 µm) thanks to higher cutting quality, higher effective cutting speed, and characteristic strength. On the other hand, cutting ultrathin glass plates (110 µm thickness) demonstrated almost identical performance and cutting quality results in both environments. In this paper, we studied cut-edge defect widths, cut-sidewall roughness, cutting throughput, characteristic strength, and band-like damage formed at the back surface of laser-cut glass strips.
GaAs ablation with ultrashort laser pulses in ambient air and water environments
Water-assisted ultrashort laser pulse processing of semiconductor materials is a promising technique to diminish heat accumulation and improve process quality. In this study, we investigate femtosecond laser ablation of deep trenches in GaAs, an important optoelectronic material, using water and ambient air environments at different laser processing regimes. We perform a comprehensive analysis of ablated trenches, including surface morphological analysis, atomic-resolution transmission electron microscopy imaging, elemental mapping, photoluminescence, and Raman spectroscopy. The findings demonstrate that GaAs ablation efficiency is enhanced in a water environment while heat-accumulation-related damage is reduced. Raman spectroscopy reveals a decrease in the broad feature associated with amorphous GaAs surface layers during water-assisted laser processing, suggesting that a higher material quality in deep trenches can be achieved using a water environment.
High numerical aperture imaging allows chirality measurement in individual collagen fibrils using polarization second harmonic generation microscopy
Second harmonic generation (SHG) microscopy is a commonly used technique to study the organization of collagen within tissues. However, individual collagen fibrils, which have diameters much smaller than the resolution of most optical systems, have not been extensively investigated. Here we probe the structure of individual collagen fibrils using polarization-resolved SHG (PSHG) microscopy and atomic force microscopy. We find that longitudinally polarized light occurring at the edge of a focal volume of a high numerical aperture microscope objective illuminated with linearly polarized light creates a measurable variation in PSHG signal along the axis orthogonal to an individual collagen fibril. By comparing numerical simulations to experimental data, we are able to estimate parameters related to the structure and chirality of the collagen fibril without tilting the sample out of the image plane, or cutting tissue at different angles, enabling chirality measurements on individual nanostructures to be performed in standard PSHG microscopes. The results presented here are expected to lead to a better understanding of PSHG results from both collagen fibrils and collagenous tissues. Further, the technique presented can be applied to other chiral nanoscale structures such as microtubules, nanowires, and nanoribbons.
High throughput wide field second harmonic imaging of giant unilamellar vesicles
Cell-sized giant unilamellar vesicles (GUVs) are an ideal tool for understanding lipid membrane structure and properties. Label-free spatiotemporal images of their membrane potential and structure would greatly aid the quantitative understanding of membrane properties. In principle, second harmonic imaging is a great tool to do so, but the low degree of spatial anisotropy that arises from a single membrane limits its application. Here, we advance the use of wide-field high throughput SH imaging by SH imaging with the use of ultrashort laser pulses. We achieve a throughput improvement of 78% of the maximum theoretical value and demonstrate subsecond image acquisition times. We show how the interfacial water intensity can be converted into a quantitative membrane potential map. Finally, for GUV imaging, we compare this type of nonresonant SH imaging to resonant SH imaging and two photon imaging using fluorophores.
High intensity femtosecond laser systems
Model | Repetition rate | Pulse duration | Max pulse energy | Special feature |
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UltraFlux HR | 1 kHz | down to 10 fs | 20 mJ | High repetition rate tunable wavelength fs OPCPA Systems |
UltraFlux HE | 100 Hz | down to 10 fs | 1 J | High energy fs OPCPA systems |
UltraFlux Custom | 1 kHz | down to 8 fs | 1 J | Custom multi TW few cycle OPCPA systems |
Model | Repetition rate | Pulse duration | Max pulse energy | Special feature |
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High-Repetition-Rate Attosecond Extreme Ultraviolet Beamlines at ELI ALPS for Studying Ultrafast Phenomena
Advancements in light engineering have led to the creation of pulsed laser sources capable of delivering high-repetition-rate, high-power few-cycle laser pulses across a wide spectral range, enabling exploration of many fascinating nonlinear processes occurring in all states of matter. High-harmonic generation, one such process, which converts the low-frequency photons of the driver laser field into soft x-rays, has revolutionized atomic, molecular, and optical physics, leading to progress in attosecond science and ultrafast optoelectronics. The Extreme Light Infrastructure, Attosecond Light Pulse Source (ELI ALPS) facility pioneers state-of-the-art tools for research in these areas. This paper outlines the design rationale, capabilities, and applications of plasma- and gas-based high-repetition-rate (1 kHz to 100 kHz) attosecond extreme ultraviolet (XUV) beamlines developed at ELI ALPS, highlighting their potential for advancing various research fields.
53 W average power CEP-stabilized OPCPA system delivering 5.5 TW few cycle pulses at 1 kHz repetition rate
We present a high peak and average power optical parametric chirped pulse amplification system driven by diode-pumped Yb:KGW and Nd:YAG lasers running at 1 kHz repetition rate. The advanced architecture of the system allows us to achieve \\&\\#x0003E;53 W average power combined with 5.5 TW peak power, along with sub-220 mrad CEP stability and sub-9 fs pulse duration at a center wavelength around 880 nm. Broadband, background-free, passively CEP stabilized seed pulses are produced in a series of cascaded optical parametric amplifiers pumped by the Yb:KGW laser, while a diode-pumped Nd:YAG laser system provides multi-mJ pump pulses for power amplification stages. Excellent stability of output parameters over 16 hours of continuous operation is demonstrated.
The ELI-ALPS facility: the next generation of attosecond sources
This review presents the technological infrastructure that will be available at the Extreme Light Infrastructure Attosecond Light Pulse Source (ELI-ALPS) international facility. ELI-ALPS will offer to the international scientific community ultrashort pulses in the femtosecond and attosecond domain for time-resolved investigations with unprecedented levels of high quality characteristics. The laser sources and the attosecond beamlines available at the facility will make attosecond technology accessible for scientists lacking access to these novel tools. Time-resolved investigation of systems of increasing complexity is envisaged using the end stations that will be provided at the facility.
Table top TW-class OPCPA system driven by tandem femtosecond Yb:KGW and picosecond Nd:YAG lasers
We present a compact TW-class OPCPA system operating at 800 nm. Broadband seed pulses are generated and pre-amplified to 25 μJ in a white light continuum seeded femtosecond NOPA. Amplification of the seed pulses to 35 mJ at a repetition rate of 10 Hz and compression to 9 fs is demonstrated.
Femtosecond fiber seeders
Model | Repetition rate | Pulse duration | Max pulse energy | Special feature |
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FFS100CHI | 25 kHz – 50 MHz | Up to 30 ps, compressible down to < 200 fs | 1 nJ | |
FFS200CHI | 100 kHz – 50 MHz | > 50 ps, compressible down to < 250 fs | 250 nJ | |
FFS200 | 25 kHz – 50 MHz | <140 fs | 5 nJ |
Model | Repetition rate | Pulse duration | Max pulse energy | Special feature |
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Compact, low-cost, and broadband terahertz time-domain spectrometer
Terahertz time-domain spectroscopy (THz-TDS) is a powerful technique that enables the characterization of a large range of bulk materials, devices, and products. Although this technique has been increasingly used in research and industry, the standard THz-TDS configuration relying on the use of a near-infrared (NIR) laser source remains experimentally complex and relatively costly, impeding its availability to those without the expertise to build a high-performance setup based on nonlinear optics or without the financial means to acquire a commercial unit. Broadband THz-TDS systems require an even larger financial investment, primarily because the generation and detection of spectral components exceeding 3 THz typically need an ultrafast NIR source delivering sub-100-fs pulses. Such an ultrafast source can be bulky and cost upwards of $100,000. Here, we present a broadband, compact, and portable THz-TDS system comprising three modules that allow for the implementation of a single low-cost ultrafast laser, hence significantly decreasing the overall cost of the system. In the first module, the output laser pulses are spectrally broadened through nonlinear propagation in a polarization-maintaining optical fiber and then temporally compressed to achieve a higher peak power. The other two modules utilize thick nonlinear crystals with periodically patterned surfaces that diffract NIR pulses and optimize the efficiency of THz generation and detection processes by enabling a noncollinear beam geometry. Phase-matching conditions in the nonlinear crystals are controlled by the period of the gratings to gain access to a large spectral THz bandwidth. The whole system, combining these three modules, provides access to a THz spectrum peaking at 3.5 THz and extending beyond 6 THz with a maximum dynamic range of 50 dB for time-resolved spectroscopy applications. We demonstrate the functionality of this configuration by performing THz spectroscopy measurements of water vapor contained within a closed cell. Our compact system design paves the way towards a high-performance, yet cost-effective, THz-TDS system that can be readily used in academia and industry.
Terahertz Spectroscopy for Gastrointestinal Cancer Diagnosis
In this chapter, we present a number of sensitive measurement modalities for the study and analysis of human cancer-affected colon and gastric tissue using terahertz (THz) spectroscopy. Considerable advancements have been reached in characterization of bio-tissue with some accuracy, although too dawn, and still long and exhaustive work have to be done towards well-established and reliable applications. The advent of the THz-time-domain spectroscopy (THz-TDS) test modality at a sub-picosecond time resolution has arguably fostered an intensive work in this field’s research line. The chapter addresses some basic theoretical aspects of this measurement modality with the presentation of general experimental laboratory setup diagrams for THz generation and detection, sample preparation aspects, samples optical parameters calculation procedures and data analysis.
On-chip visible-to-infrared supercontinuum generation with more than 495 THz spectral bandwidth
We report ultra-broadband supercontinuum generation in high-confinement Si3N4 integrated optical waveguides. The spectrum extends through the visible (from 470 nm) to the infrared spectral range (2130 nm) comprising a spectral bandwidth wider than 495 THz, which is the widest supercontinuum spectrum generated on a chip.