This PDF file contains the front matter associated with SPIE Proceedings Volume 12411, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

New industrial applications of femtosecond lasers are continuously emerging in various industrial sectors: health, production, energy, transport. Fiber delivery of femtosecond pulses and power is a key enabling technology for opening industrial application fields much wider: conventional micromachining stations typically based on ultrastable and ultraheavy granite tables are avoided and the femtosecond laser is coupled into a flexible light guide instead. Ultraprecise machining processes can such be displaced far from the femtosecond laser source and coupled to moving axes or robot systems. Here, we report on a femtosecond fiber delivery system for industrial applications. In a first demonstration, the delivery system is coupled to a Satsuma industrial femtosecond laser with average output power of more than 20 W and pulse energy up to 60 μJ. Polarization control allows addressing any kind of micromachining applications, also those sensitive to the polarization state incident on the workpiece. Coupling of the fiber delivery system to a robot system and the nanotexturing by LIPSS will be here reported. Comparisons of the obtained results with conventional micromachining applications using free beam propagation are drawn and future perspectives to higher laser powers and energies as well as to wavelength converted femtosecond pulses discussed.

We developed a high-power femtosecond tunable light source with over 20 mW output and emission in the 1650-1900 nm region, which is the boundary region between near-infrared (NIR) and mid-infrared (MIR). The light source’s output power per unit wavelength and irradiation area are 10,000 times higher than general halogen lamps we tested. These unique features of the technology enable the spectral measurement of thick biological samples, which has been considered impossible using a lamp light source. In addition, the light source’s all-fiber system requires no vibration isolator, no clean room, and no optical axis adjustment. Using a simple optical measurement system, we demonstrated absorption measurements of pork lipids about 0.9 mm thick and confirmed the light source had sufficient output power to penetrate the sample. We also present application examples that can benefit from the light source’s high-power light intensity.

Using lasers for permanent markings is a well-known method and standard in many areas in industrial manufacturing. Various processes on all kinds of materials are used to achieve durable markings, where the content is often serial numbers, codes and company logos. Whereas laser marking processes are mostly easy to handle it becomes challenging if the markings need to fulfill the requirements of the medical industry. The demand for markings in the medical industry is increasing because of the regulations in this sector. The labelling of medical devices with a traceable Unique Device Identification (UDI) code has become mandatory. Laser marking of medical steel needs to fulfill certain criteria where corrosion resistance, a toxicologically uncritical surface and good contrast, are key factors. Standard laser marking systems are reaching their limits to fulfill these criteria. The best choice to accomplish this challenge is the usage of ultrashort pulsed (USP) lasers. The process using USP lasers, fulfilling the criteria of medical industry, is often called “black marking”. We use the TruMicro Mark 2030 G2 S. This laser has the advantage of full flexibility of the important parameters, such as pulse energy, pulse frequency and pulse duration. Due to the great necessity for reliable medical devices, we investigate the effect of varying different laser parameters on the resulting structures of the black marking process on stainless steel in an experimental study. Analyzed is the dependency of the resulting structures on the energy density by varying the laser spotsize. This is adjusted by a parameter in the marking software and can be set continuously. The dependency of the resulting structures on the pulse duration is investigated by varying the pulse duration. The pulse duration is adjusted by a parameter in the marking software and can be tuned in the range of 400 fs to 20 ps at 100 fs increments. The fundamental parameters like beam quality, beam pointing or energy stability are not affected by changing the pulse duration. The fast switching time of < 800 ms enables for intra-process tuning of the temporal energy deposition. Analyzing the results by a Scanning Electron Microscope (SEM) reveals different surface structures. The structures change in its appearance, periodicity, and groove depth. Various of the described structures can give a permanent black contrast and fulfill the requirements of medical industry.

Ultrafast laser ablation supersedes conventional surgical techniques in terms of precision and thermal load generation. However, the main limiting criterion of the application of laser ablation techniques to surgeries has been the low material removal rate (MRR). In efforts to bridge the gap, a benchtop fiber-baser laser delivery system has been developed which demonstrated a MRR increase of ~15 times over the previously reported fs-laser surgical probes. The benchtop optical setup incorporates a hollow-core Kagome fiber (NA≈0.02) delivering high-power laser pulses from the Yb-doped fiber laser (λ=1035 nm) source to the sample. A Lissajous-based beam steering mechanism was employed to distribute the ultrashort laser pulses on the sample. The overall transmission efficiency of the system was 59%, with none of the components exhibiting any non-linear behavior at high peak intensities. For a FOV scan width of 250 μm, the logarithmic relationship between the ablation depth and laser fluence was determined for two different translational velocities. The system achieved material removal rates of ~2 mm³/min for the maximum applied laser fluence of 18.9 J/cm², without initiating carbonization. Additionally, optimized laser parameters were implemented to achieve a clean-cut trench of 3 x 0.8 μm² size and ~1.22 mm deep in under 3 minutes of laser exposure, which is within the surgical time bounds of a conventional spinal decompression technique. The fact that the trench is devoid of any carbonized section or unhealthy tissue, and was created without any irrigation setting only increases the reliability and viability of the ultrashort-laser ablation technique in surgical applications.

Femtosecond laser processing of bone tissue has shown great potential for osteotomy procedures where high precision cutting and the preservation of bone tissue functions are of primary importance. Nonetheless, the ablation rates related to this kind of process still remain too low for this technology to be exploitable in a real surgical procedure. Moreover, the strong dependence of the process outcomes from factors such as the processing environment, the type of pre-processing and post-processing treatment of the bone tissue, the species of the processed animal and the bone part itself, stall the full development and advancement of this technique. This study highlights the key role of the anatomical region (femur, tibia, etc.) and species (pig, chicken, etc.) of the investigated bone tissue samples to provide a solid reference on the impact of the choice of types of samples on laser ablation studies of bone tissue. Results show that it is essential to choose the best animal model for a specific case study, which depends to a large extent on the objectives of the research subject. There are no perfect animal models: the selection of one animal model is often associated with its similarity to the human model because the goal is the validation of experiments in clinical setting. However, most studies do not take these variabilities into account in their conclusions.

We report a joint experimental and theoretical study of a three-sideband (3-SB) modification of the “reconstruction of attosecond beating by interference of two-photon transitions” (RABBIT) setup. The 3-SB RABBIT scheme allows to investigate phases resulting from the interference between transitions of different orders in the ionization continuum. The strength of this method is its ability to focus on the angle-dependent atomic phases only, independent of a possible spectral chirp of the exiting EUV fields. Furthermore, with a traditional 1-SB RABBITT scheme, we observe an asymmetry of the electron emission direction with respect to the proton after few-photon dissociation of molecular hydrogen and present sub-femtosecond control of this emission direction.

We introduce a hybrid CPA system of Yb-doped fibers and Nd:glass rods, with use of aperiodic-frequency-converter crystal around 526 nm, demonstrated ~40% efficiency, and ~40 dB pulse contrast improvement. New result with novel SLT-made-AFC yielded ~60% efficiency, both showed near full bandwidth conversion. A Neodymium:glass CPA pulse yielded record energy result of 320s μJ in 527 nm second harmonic with the LiNBO₃. Additionally, new, very low-cost, robust method, based on time-space nonlinear-index self-focusing effect showed >20-dB contrast enhancement.

Photolithography assisted chemo-mechanical etching (PLACE), a technique specifically developed for fabricating high-quality large-scale photonic integrated circuits (PICs) on thin-film lithium niobate (TFLN), has enabled fabrication of a series of building blocks of PICs ranging from high-quality (high-Q) micro-resonators and low-loss waveguides to electrooptically (EO) tunable lasers and waveguide amplifiers. Aiming at high-throughput manufacturing of the PIC devices and systems, we have developed an ultra-high-speed high-resolution laser lithography fabrication system employing a high-repetition-rate femtosecond laser and a high-speed polygon laser scanner, by which a lithography fabrication efficiency of 4.8 cm2/h has been achieved at a spatial resolution of 200 nm. We demonstrate wafer-scale fabrication of TFLN-based photonic structures, optical phase masks as well as color printing.

Stress waves propagating inside materials play a significant role in femtosecond laser processing. In this study, we measured femtosecond-laser-induced stress waves inside synthetic silica glass using a time-resolved Mach–Zehnder interferometer. A laser pulse with a wavelength of 1030 nm, pulse width of 180 fs, and pulse energy of 100 μJ was used to induce stress waves. The three-dimensional distribution of the refractive-index change of the stress wave was obtained via reconstruction using the inverse Abele transform. This result contributes to the further development of femtosecond laser processing.

The laser-based fabrication of glass substrates with chamfered edges and arbitrary contour geometries is reported. To achieve energy deposition along any edge geometry, a holographic beam splitter is used generating a large number of focus copies in the bulk of transparent materials. If an adapted rotation of the focus distribution is additionally used during machining, the production of substrates with arbitrary contours, such as circular or display geometries, is enabled. After the laser modification step, separation is achieved using a selective laser etching strategy. The advantages of our process are discussed using selected process results and associated laser parameters.

In this study, we patterned structures composed of graphitic and silicon carbide nanocrystals by the laser-induced carbonization of polydimethylsiloxane. The average size of the observed silicon carbide nanocrystals varied depending on the energy per laser pulse, or pulse energy, used for patterning, where larger crystals were observed for structures patterned with higher pulse energies. Moreover, the electrical property of the patterned structure shifted from conductive to semiconductive, as the pulse energy for patterning increased. To the best of our knowledge, this is the first demonstration of the patterning of structures exhibiting measurable semiconducting properties by the laser-induced carbonization of polymers.

Ultrafast laser writing enables fabrication of three-dimensional structures (sub-micron scale) inside the bulk of diamond. High intensities in the focal volume of the laser cause lattice breakdown; as a result, diamond is transformed into a graphitic phase. Laser written graphitic wires embedded in the single crystal diamond find an application for electrodes in diamond detectors. Laser processing of graphitic columns requires a combination of certain parameters, including power, repetition rate, translation speed. Here, we explore the effect of the laser pulse energy on the electrical resistance of laser written graphitic columns that pass through the thickness of a CVD single crystal slab. We introduce a scheme that allows straightforward electrical analysis of the columns in an all-carbon device, without additional processing of the diamond, that allows for rapid optimisation of the laser parameters.

1030 nm Ytterbium based solid state femtosecond lasers are key to robust NUV (3rd harmonic) and DUV (4th and 5th harmonic) generation. Industrial applications demand high average powers and often high pulse energy simultaneously. We will present the most up to date results in 3H; 4H; 5H; 6H and even X-ray generation. Lifetime, pulse to pulse and long-term stability, beam quality and especially warm-up time are critical factors for industrial applications and are often dismissed, therefore will be reviewed in detail. We will also add projections to our near future development based on the market needs. Various novel achievements already incorporated into our products such as beam shaped output directly from the module; pico- and nano- second spaced bursts in UV; peculiarities of generating UV with chirped and bandwidth limited pulses will be presented. We will discuss the lifetime testing results, the factors limiting it and the solutions aimed at extending it. We will present the results of our built-in diagnostics quality and lifetime as the requirements for accurate measurements in UV range are no less challenging.