Lasers and Photonics for Advanced Manufacturing

I will explore various facets of photonic quantum systems and their application in photonic quantum technologies. Firstly, I will focus into quantum foundations and by discuss quantum interference, a key element in photonic quantum technologies. I will highlight how the distinguishability and mixedness of quantum states influence the interference of multiple single photons – and demonstrate novel schemes for generating multipartite entangled quantum states. I will then address photonic quantum computing, specifically focusing on the building blocks of photonic quantum computers. This includes the generation of resource states essential for photonic quantum computing. I will then shift to photonic quantum networks, covering both their hardware aspects and showcasing quantum-network applications that extend beyond bi-partite quantum communication. Lastly, I will outline how photonic integration facilitates the scalability of these systems and discuss the associated challenges.

Joining the rich photophysics of organic light-emitting materials with the exquisite sensitivity of optical resonances to geometry and refractive index enables a plethora of devices with unusual and exciting properties. Examples from my team include biointegrated microlasers for real time sensing of cellular activity and long-term cell tracking, as well as the development of photonic implants with extreme form factors and wireless power supply that support thousands of individually addressable organic LEDs and thus allow optogenetic targeting of neurons deep in the brain with unprecedented spatial control. Very recently, by driving the interaction between excited states in organic materials and resonances in thin optical cavities into the strong coupling regime, we unlocked new tuning parameters which may play a crucial role in the next generation of TVs and computer displays to achieve even more saturated colour while retaining angle-independent emission characteristics.

We will present recent developments in femtosecond lasers based on Holmium materials emitting around 2.1µm, including modelocked disk lasers with record high average power based on Ho:YAG and new GHz high-power oscillators with sub-100 femtosecond pulses using the new material Ho:CALGO. We will also discuss areas of application where these lasers promise to open new opportunities.

High average power femtosecond (from 100 W to 1 kW) with higher productivity open access to new and large markets of “macro” processing unreachable so far for fs processing (Aeronautics, Energy and Mobility, etc.). This work will present an interesting example of optimization in the technical field of aerodynamic performances, but developed methods can be applied on other application fields. Using a kW femtosecond laser, drilling of holes on Titanium with 0.8 mm thickness can be achieved at a drilling speed of 150 holes per second. The surfacing speed for Riblets is today near 1 cm2/min and expected to reach 25 cm2/min by combining a 300 W fs laser with a spatial shaping of multiple square spots.

We present in this contribution a Yb:YAG thin-disk multipass amplifier delivering sub-2 ps pulses with kilowatt of average output power at a highly flexible repetition rates ranging from MHz to several GHz. The system, developed within the european project kW-Flexiburst, delivers laser pulses from single pulse to bursts of pulses with arbitrary number of pulses (1, 3, 5, …, 1000) at up to 7.5 GHz of intra-burst repetition rate. A seed laser delivering stretched pulses at an average output power of 50 W for a single pulse configuration and up to 230 W for GHz-bursts with more than 3 pulses/burst was used. In a single pulse configuration, an average output power of up to 655 W whereas up to 1090 W were extracted in burst operation at an intra-burst repetition-rate of 1GHz. During the talk, few examples of applications using our laser will be presented.

We report on a high-performance laser milling process and system for the fabrication of large arbitrarily shaped geometrical structures in silicon. A custom designed multi-step approach combining high speed nanosecond laser ablation (roughing) with high precision ultrashort pulsed ablation (finishing) and inline 3D-measurement allows for the realization of large-volume cavities of up to and exceeding 20 mm³ with virtually freely selectable geometry at very high ablation rates Rabl > 0.1 mm³/s while maintaining high surface quality (Sa < 0.5 µm) on the laser processed areas.

Femtosecond GHz-burst mode laser processing of glasses and silicon has attracted much attention in the last few years. Especially, top-down percussion drilling has been demonstrated in glasses with outstanding quality. There is a big interest in drilling through vias in glasses (TGV) and semi-conductors, especially in silicon (TSV) for applications in microelectronics. In this contribution, we present through via drillings in these materials with a femtosecond laser operating in the GHz-burst regime. Our study reveals certain constraints and limits in through via drilling depending on the material characteristics and on the laser parameters. We show how to overcome these limits and demonstrate through via drilling results of excellent quality and constant diameter in both glasses and silicon.

We compare different pulse durations, modes and repetition rates of infrared ultrashort pulses lasers for the inscription of printed electronics sensors under 100 µm scale. We investigate pulse widths varying from 200 fs up to 10 ps, and standard single pulse versus 5 GHz burst regimes to produce the most efficient and cleanest ablation. The aim of the investigated process is to ablate a layer of conductive material like carbon, NiAl or NiCr forming the electronic track contours, without damaging the support which is made of a dielectric insulator. Depending on the materials and substrates of the printed electronics circuits, we have observed that 10 ps pulses in GHz burst regime with moderate individual pulse energy (around 10 µJ) have a lot of potential for an efficient production.

In this experimental study, a high power femtosecond laser delivering long GHz bursts was use to compare the influence of the wavelength on the quality and the specific ablation rate of selected materials.

Here, we present very low pulse energies (below 200 nJ) at very high speed (over 100 kHz) LIBS experiment by employing our recently developed 25 ps, 14W, 2.8 GHz intra-burst repetition rate Yb-doped fiber laser system. To carry out the LIBS experiments, the laser beam is directed into a Galvo scanner and focused through a 56 mm long F-theta lens onto different materials, including steel, copper, aluminum, and silicon. Our investigation of LIBS encompassed various parameters, including varying pulse energies, the number of intra-burst pulses, and burst repetition rates. For instance, with a burst repetition rate of 100 kHz with 83 ns burst width (232 intra-burst pulses), we observed the threshold pulse energy stands at approximately 26 nJ for LIBS experiment on steel. Furthermore, at about 200 nJ, it is enough to keep a high signal-to-noise ratio. To the best of our knowledge, this is the first report on LIBS experiment by GHz-range laser operating in the burst mode regime.

There is a growing interest in on-the-fly adaption of laser intensity profiles and parallel use of multiple laser beams to increase productivity in laser materials processing applications. Typically, achieving this involves incorporating diffractive optical elements (DOE) between the laser source and the 2D scan head, enabling the use of shaped intensity profiles or multi-beam matrices within the scan field. However, scanning introduces distortions, impacting accuracy during laser processing. The presented solution combines static relay optics and innovative actuators to address this, employing a cascaded optical system with a novel actuator design for dynamic rotation of a beam-splitting or shaping DOE. This rotation compensates for distortions, enhancing spot position accuracy. Simulation tools evaluate achievable accuracy, and a functional prototype demonstrates the potential for flexible parallel laser processing with high dynamics, showcasing a promising advancement in laser materials processing technology.

Significant performance improvement of laser welding, brazing, cladding based on multi-kW lasers is achieved using multi-spot beam shaping optics optimizing energy distribution in working plane through variable energy sharing between several spots. Various spot patterns, such as square, line, rhombus, consisting of 4 or 9 separate spots provide reduction of spatter and weld porosity due to optimum temperature distribution in the melting pool by welding of tailored blanks, copper and aluminium parts in batteries production, etc. Effective beam shaping of powerful multimode lasers, characterized by low spatial coherence (large M²), is realized through angular splitting the beam in several beamlets with further focusing in compound spot patterns with variable energy portions and distances between the spots. Optics with smooth optical surfaces made of materials self-compensating thermal focus shift ensures reliable operation with multi-kW lasers. The paper presents the proposed multi-spot optics, shows intensity profile measurements and application results.

In this presentation, we introduce a novel approach to machining surfaces using femtosecond (fs) UV laser systems. We explore the potential of these systems for large-area surface patterning, specifically in processing high band-gap materials like sapphire and yttrium aluminium garnet (YAG). The existing techniques are not satisfactory in terms of etch rates and accuracy, which our research is addressing. We demonstrate the use of two-beam fs-UV interference patterning to create harmonic gratings with exceptional accuracy. Key aspects include controlling the pulsed nature of the beams, optimizing pulse delay and spatial overlap, and comparing various beam splitting techniques. Our findings indicate that we can achieve sub-25 nm precision in material removal, which is a significant improvement over existing technologies. This research not only enhances the efficiency and accuracy of surface machining but also opens up new possibilities in advanced photonic applications.

Optical tools used in laser materials processing often include focusing units designed with ray tracing-based spatial design tools. Here, operating near the spatial diffraction limit is a standard quality criterion. However, when ultrashort pulses are focused a consistent performance is only achieved for 1ps pulses or longer. Our computational analyses focus on ultrashort pulses below 100fs, revealing the impact of dispersive properties on industry-grade focusing units. We investigate high-NA microscope to f-theta objectives and evaluate peak intensities and symmetry breaks. Additionally, we examine the effects of spatial beam shaping and uncover associated spatio-temporal focusing phenomena, for example, when ultrafast Bessel-like beams are generated. This provided insights into the challenges and opportunities for enhancing precision in industrial applications that use shaped ultrashort laser pulses.

Laser Shock Peening has shown in the past decades its efficiency over other techniques to enhance the fatigue resistance of parts. However, its use is still limited to certain applications as it is complex to implement (high-footprint, free-space propagation, sacrificial layer management). In this publication, we introduce the Fibered Laser Shock Peening System (FLASP), which consists of a fiber coupling module, an optical head to focus the beam on the part, and an optical fiber to link both modules. Energetic laser beam transmission through optical fibers requires specific beam shaping as it is necessary to suppress spatial profile modulations caused by speckle. For this matter, the spatial coherence of the beam was reduced in order to obtain a smooth circular beam profile at the fiber entrance. Such a setup made it possible to couple a record 380mJ in a 1.5mm core optical fiber which corresponds to a peak power of 63MW at a pulse duration of 6ns. Such energy levels have not damaged a 5m fiber for more than 50 million shots. The FLASP system successfully treated aluminum, titanium and steel parts for which compression peaks reached -400MPa while the affected depth exceeded 1mm.

Holographic beam shaping that is performed with a computer-generated hologram displayed on a spatial light modulator. It is very useful for many kinds of scientific and engineered applications. The temporal and spatial stabilization is indispensable for them, especially, for the material laser processing, because it requires a high quality beam in short and long terms. In our research, the stabilization is performed with an observation of the intensity distribution that is easily detected by a simple optics and an ordinary image sensor.

We will present recent advances in direct bonding of dissimilar materials like glass to metal, silicon or ceramics using ultrashort lasers. The process can potentially displace traditional bonding techniques such as epoxy, diffusion, anodic, etc offering a clean, fast and flexible new alternative. It relies on highly controlled laser heat input from <10ps pulses along a user-defined toolpath at the material interface and has been proven to work on various material combinations including BK7, quartz, fused silica, sapphire glasses of varying size, thickness and shape with metals (aluminium, s.steel, titanium, etc), silicon and ceramics (silicon nitride).

We applied the 3D fabrication capability of ultrafast laser to fabricate 3D functional micro and nanodevices for chemical and biological applications. Applications of the fabricated devices include 3D micro and nanofluidic systems to elucidate mechanism of cancer cell metastasis and invasion in the human body, diagnostic microchips based on advanced digital nucleic acid amplification technique (d-NAAT), such as digital polymerase chain reaction (d-PCR), which consists of an array of more than 10,000 micro-through-holes on glass substrates, and 3D microfluidic surface enhanced Raman spectroscopy (SERS) chips enabling real-time sensing and attomolar level sensing of chemical and biological samples.

The exploration of sustainable materials derived from natural sources gains prominence, attributing to their renewable nature and minimal ecological footprint upon disposal. Integrating such sustainable materials into the design of electrical and optical devices holds the promise of realizing an ecologically harmonious society. In this presentation, our study on laser-induced carbonization and graphitization of natural materials using a femtosecond laser will be described. Specifically, we demonstrate the direct patterning of conductive structures on biodegradable materials by laser-based graphitization. By measuring the temperature of the material by varying the repetition rate of laser pulses, we revealed that the properties of the generated material change not only based on the highest temperature but also on the temporal variation of temperature. Furthermore, we have expanded the technique for the fabrication of a metal-free supercapacitor and triboelectric nanogenerator (TENG) by laser-induced graphitization.

A promising approach to enhance the electrochemical properties of a lithium-ion battery is the use of a high-voltage cathode material in combination with a three-dimensional electrode architecture created through laser structuring. For that, the ablation behaviour of the high-voltage cathode must be investigated. LiNi0.5Mn1.5O4 (LNMO) cathodes produced through NMP-based or water-based electrode processing methods are laser structured using a high-power ultrashort pulsed laser source. An investigation and a comparison of the ablation behaviour of the different LNMO cathodes is performed by a variation of laser and process parameters. The impact of the laser fluence, the repetition rate, and the pulse overlap on the ablation depth and width as well as on the aspect ratio is analysed.

The laser-assisted generation of three-dimensional electrode architectures requires coordination with other established manufacturing steps in the battery production process. In particular, the calendering of electrodes holds great importance as it has a significant impact on the microstructural properties of the electrode material, including porosity, material density, and layer adhesion. The study investigated the impact of laser-induced hierarchical structuring, comprising micro-/nano-porosities and microtopography, on electrodes with varying mass loadings from 2mAh/cm² to 6mAh/cm². In this regard, cells comprising graphite anodes and lithium-nickel-manganese-cobalt oxide cathodes were prepared and subjected to electrochemical characterization techniques.

The electric double-layer capacitor (EDLC) is an energy storage device distinguished by its relatively extended cycle life and rapid charge-discharge capabilities. Heightened capacitance of the EDLC aligns with an augmented specific surface area of the electrodes. In this study, we employed laser-induced graphitization of a biodegradable composite sheet containing NaHCO3 to fabricate a conductive porous carbon structures serving as EDLC electrodes. Pores were observed on the surface of the composite sheet containing NaHCO3 after laser irradiation. It is considered that the formation of pores, accompanied by gas generation from the thermal decomposition of NaHCO3, led to an increase in the specific surface area of the structures and improved capacitance. Our method extends the potential of environmentally compatible, plant-derived materials for device applications.

Among different technologies dealing with additive manufacturing (AM), Laser Induced Forward Transfer (LIFT) is a sustainable and precise manufacturing technology, that shows high potential for industrial application. Here, we propose the use of LIFT to efficiently print metallic patterns and solder materials on PIC chips. This study explores two donor substrates for gold deposition: evaporated gold layers on glass and gold nanoparticle inks, and one donor substrate for solder paste deposition. Parameters like layer thickness, laser scanning speed, donor-receiver gap distance, laser fluence and pulse shape are optimized for quality transfer. Optimization of the LIFT process parameters will enable the reproducible and controllable printing of electrodes for creating an all-printed graphene-based photodetector and the solder paste deposition for assembly applications.

The interest in manned deep space exploration and long-term stays has grown recently for government but also for the private sector. To develop a safe and sustainable infrastructure for future missions, In-Space Manufacturing has to become state of the art. This paper will propose a novel handling mechanism for powder-based material suitable for the microgravitational environment. Ultrasonic levitation is a promising technology for gravitational independent material handling. The fundamental challenge lies in the trapping of powder-based materials. To assist the material deposition process and stabilize the material handling water is used as a carrier material. A multi emitter single axis ultrasonic levitator is employed to levitate Nylon 12 SLS-powder in a fixed state and initiate a laser melting process to bound the powder material. Previous investigations have shown a stable levitation of liquid and solid materials. For the first time it was possible to levitate, and laser melt a SLS material inside an ultrasonic levitation field, enabling a novel handling technology for the microgravitational environment.

Multiphoton Lithography stands as a laser-driven additive manufacturing method, enabling the creation of structures with remarkable resolution, reaching down to the scale of tens of nanometers. Leveraging nonlinear absorption, this technique boasts distinctive capabilities unmatched by other methods. Diverse materials have been successfully employed in its implementation, resulting in the production of various components and devices such as metamaterials, biomedical devices, photocatalytic systems, and mechanical models. The distinguishing feature of Multiphoton Lithography lies in its ability to actualize computer-designed, fully operational 3D devices. This presentation provides a comprehensive overview of microfabrication principles, highlighting recent advancements in materials processing and the functionalization of 3D structures. To conclude, an exploration of future applications and the technology's prospects is presented.

This study addresses the challenges of adding functionality and hybridizing processes in additive manufacturing. It focuses on embedding a gold-coated optical fiber into an INOX structure, aiming to extend this process to optical sensors like fiber Bragg grating arrays. The primary concern is the sensor's resistance to high temperatures during metal deposition, while the second challenge involves the adhesion of filler material to the sensor and structure. The feasibility is assessed through a finite element thermal model and mechanical testing, confirming the process's viability. Successful light transmission through the fiber and tensile tests indicate structural integrity and reduced ductility, warranting further investigation under varying load conditions.

Metal additive manufacturing is currently experiencing strong growth in the industry. Until recently, it remained confined to small dimensions, a consequence of the limits imposed by the technologies used (mainly PBF (Powder Bed Fusion) technology). Today, suppliers offer large PBF machines using numerous lasers to ensure sufficient manufacturing speeds. Furthermore, another large-scale offer is based on the use of DED (Directed Energy Deposition) processes which use an energy source (for example Laser) to melt a deposited filler material to form the volume layer after layer. of the room. IREPA LASER has therefore developed a new technology capable of manufacturing or repairing XXL parts (up to 5 meters in length and weigh up to 5 tonnes). This technology is based on a head for depositing one or more molten metal wires using a high-power laser (10kW). This presentation will be an opportunity to take stock of the evolution of additive manufacturing technologies, and to present the latest results obtained in the field of DED, but also to show that the laser has become essential in manufacturing industries.

Laser Additive Manufacturing (LAM) offers a versatile approach to fabricate composite materials, including heterogeneous and transition materials, characterized by exceptional mechanical properties. In this study, TiN/Ti6Al4V sandwich structural materials were prepared by the Selective Laser Melting (SLM) and Laser Directed Energy Deposition (LDED) processes, each in distinct environments featuring varying nitrogen-to-argon ratios. We conducted a comprehensive investigation, comparing the elemental diffusion, in-situ synthesis, microstructural characteristics, and mechanical properties of TiN/Ti6Al4V sandwich structural materials produced via these two processes. In both SLM and LDED processes, the in-situ synthesis of TiN from titanium and nitrogen atoms yielded robust metallurgical bonds with the Ti6Al4V matrix. The superior performance of TiN/Ti6Al4V sandwich structural materials achieved through LAM results from their laminar structure and the reinforcing effect of internal ceramic particles. Leveraging the combination of soft and hard layers within the sandwich structure, the tensile strength significantly surpasses that of homogeneous materials. Specifically, the sandwich str

It is presently challenging for selective laser melting (SLM) additive manufacturing technique to fabricate metal parts with wall thickness below 100 m. This work investigated the critical conditions of the extremely thin wall thickness of tungsten grids fabricated by SLM. Specifically, the effect of low energy density on the printability of tungsten single tracks and grids via SLM was studied. A thermofluid flow model of the molten pool created in the SLM process was developed based on a computational fluid dynamics approach to illustrate the single-track morphology variation corresponding to printability. The findings demonstrate that at low energy densities, the molten track exhibits four different morphologies: balling, discontinuity and winding, discontinuity but straightness, as well as continuity and straightness. The simulation model, reliably validated by these results, effectively reveals the correlation between printability and the extent of melting in the powder bed. The energy density impacts the heat transfer mechanism and recoil pressure magnitude within the molten pool, thereby determining its flowability to fill voids in the powder bed. Additionally, the grid morp

Optical cavities with nonlinear elements and delayed self-coupling are widely explored candidates for photonic reservoir computing (RC). For time series prediction applications that appear in many real-world problems, energy efficiency, robustness and performance are key indicators. With this contribution I want to clarify the role of internal dynamic coupling and timescales on the performance of a photonic RC system and discuss routes for optimization. By numerically comparing various delay-based RC systems e.g., quantum-dot lasers, spin-VCSEL (vertically emitting semiconductor lasers), and semiconductor amplifiers regarding their performance on different time series prediction tasks, to messages are emphasized: First, a concise understanding of the nonlinear dynamic response (bifurcation structure) of the chosen dynamical system is necessary in order to use its full potential for RC and prevent operation with unsuitable parameters. Second, the input scheme (optical injection, current modulation etc.) crucially changes the outcome as it changes the direction of the perturbation and therewith the nonlinearity. The input can be further utilized to externally add a memory timescale that is needed for the chosen task and thus offers an easy tunability of RC systems.

Programmable photonic circuits manipulate the flow of light on a chip by electrically controlling a set of tunable analog gates connected by optical waveguides. Light is distributed and spatially rerouted to implement various linear functions by interfering signals along different paths. A general-purpose photonic processor can be built by integrating this flexible hardware in a technology stack comprising an electronic monitoring and controlling layer and a software layer for resource control and programming. This processor can leverage the unique properties of photonics in terms of ultra-high bandwidth, high-speed operation, and low power consumption while operating in a complementary and synergistic way with electronic processors. This talk will review the recent advances in the field and it will also delve into the potential application fields for this technology including, communications, 6G systems, interconnections, switching for data centers and computing.

The automotive industry has made advancements in safety technology, and airbags play a pivotal role in protecting passengers during accidents. Precision cutting of airbag textile materials is one of the important processes for ensuring the effectiveness and performance of such equipment. The aim of this work is to compare three dedicated scanning systems employed for CO2 laser cutting of airbag textile material in the automotive sector: (i) a system plotter (i.e., a traditional laser setup with a fixed cutting bed); (ii) fixed 2D galvanometer scanner (GS), commonly used for laser cutting in more compact and automated environments; (iii) mobile 2D GS, with an increased portability and versatility in comparison to the previous solution. Specific parameters, advantages and drawbacks of each system for the targeted application are presented and compared. Examples of manufacturing are presented. The choice between such scanners is discussed in a trade-off between quality and productivity.

Laser powder bed fusion can rapidly manufacture metal entities with complex structures, but the highly surface roughness and low dimensional accuracy limit the mechanical properties and application scenarios of powder bed process parts. In recent years, ultrafast laser micromachining has shown great potential in the field of precision machining. Therefore, ultrafast laser machining was combined with laser powder bed manufacturing in this study. After additive manufacturing, the additively molded samples were micromachined using ultrafast laser. In this study, a laser powder bed fusion device equipped with a picosecond laser is described, and a preliminary realization of additive and subtractive manufacturing based on pulsed laser processing using this device is presented. The side surface roughness of the samples fabricated by hybrid additive manufacturing process was lower than that of as-built LPBF samples. This work may provide a new way to manufacture parts with high dimensional accuracy and low surface roughness by LPBF.

The behaviour of three commercial polymers (poly(vinyl chloride) (PVC), poly(ethylene terephthalate) (PET) and polypropylene (PP)) under high frequency (10 kHz – 1 MHz) femtosecond laser (450 fs) multi-pulse irradiation is analysed at three different wavelengths: λ= 343 (1.34 J/cm2), 515 (1.34 J/cm2) and 1030 (1.70 J/cm2) nm. Controlling the ultrafast processing of polymers becomes challenging because their low absorbance and their high-volume changes produced by phase transitions at low temperatures. However, using ultrafast pulses with appropriate laser conditions can produce successful modifications on these materials. High frequency irradiations result into better uniformity ablation areas that are suitable for developing tunable waveguides on flexible substrates. Processed regions are characterized by Micro-Raman spectroscopy and SEM and AFM measurements.

Exploring nuclear ceramic (UO2) behavior is crucial for advancing safety and efficiency in the energy sector. Our study employs femtosecond laser ablation for micromachining, focusing on thermal impact control through innovative methodologies. Using finite element model and high-speed thermal camera, we quantify and minimize the heat-affected zone. Demonstrated on model materials, our approach exhibits temperature control, safeguarding microstructure integrity. While early in applying this to real nuclear fuel samples, our study paves the way for future applications in nuclear fuel fabrication, representing a significant leap in understanding nuclear ceramics behavior and fuel machining.

We introduce a single-mode Erbium-doped master oscillator power amplifier (MOPA) fiber laser, capable of directly generating 100 fs pulses at 2.2 W and 120 fs pulses at 4.5 W of average power. This laser operates at a pulse repetition rate of 1.2 GHz with a repetition rate multiplier, at the central wavelength around 1550 nm. The laser system comprises a passively mode-locked oscillator with a repetition rate of 77.6 MHz and an average power of 16.3 mW followed by a repetition rate multiplier and a cladding-pumped co-doped Er-Yb fiber laser. 100 fs long pulses, as the shortest pulse duration, was directly achieved at an output power of 2.2 W. In this experiment, the pulse dynamic at different output powers has been studied and verified by simulation. This developed system is employed in micromachining and sub-surface silicon processing at low pulse energy at a GHz-range repetition rate.

We demonstrate a novel method for the simultaneous inscription of two spectrally separated fiber-Bragg-gratings (FBGs) at the same spot with the femtosecond laser technique. This technique is experimentally demonstrated on a commercial single-mode-fiber at a Bragg wavelength of ~1.55µm. The inscription setup consists of an amplified near-IR femtosecond laser, two Phase-Masks (PM), two cylindrical focusing lenses, a negative defocusing spherical lens, and a 50%:50% beam-splitter. Each beam containing ~50% of the energy is focused through a 2140nm period PM, and a 40mm cylindrical lens at the same spot of the optical fiber; the first from one side of the fiber, and the second from the opposite side. This ensures the simultaneous inscription of two FBGs at the same spot. The wavelength separation between the two FBGs is achieved by defocusing one of the beams with a negative spherical lens. The transmission and reflection spectra of the two FBGs are measured.

Laser-induced plasmas are crucial in energy deposition in dielectrics during ultrafast laser processing, with implications for various applications. However, accurately quantifying plasma density distribution remains challenging. This study proposes a novel imaging technique for mapping plasma generated by Bessel beams in the bulk of dielectrics. By analyzing wave-turning phenomena in images of laser pump pulses interacting with the sample, plasma dimensions are extracted, revealing scales smaller than the optical resolution limit. Results align well with advanced numerical simulations using the Particle-In-Cell approach.

Laser-induced periodic surface structure (LIPSS) can be generated using femtosecond laser in numerous materials, as stainless steel. LIPSS can modify the polarization state of the transmitted or reflected radiation. Nevertheless, LIPSS are not usually are imperfect since its quality strongly depends on the homogeneity of the surface and the optical properties of the light beam. In this work we analyze how random fluctuations of LIPSS topography may modify the polarimetric properties and produce depolarization.

Diffractive Optical Elements (DOEs) modulate the properties of a light beam like the amplitude, phase, or coherence polarization so they are useful in fields such as beam shaping or holography. Femtosecond Laser Direct Writing (FLDW) is a promising technique to manufacture these devices as it is a clean, contactless, and chemical free method. We have used it to fabricate binary phase DOEs over a dielectric material, fused silica, with the aim of using them for femtosecond laser micromachining. We have analyzed the structure of the manufactured DOEs and their far-field diffraction patterns.

Laser percussion drilling of micro-holes has established itself as a prominent micro-machining technique rivalling both conventional and non-conventional micro-drilling processes. Despite its broader use, the laser percussion drilling process has some limitations, particularly the achievable micro-holes’ accuracy. The research reports a novel method to address this shortcoming by improving the holes’ dimensional and geometrical accuracy. Especially, the proposed two-side method for laser percussion drilling of micro holes utilizes a penetrating laser beam that is refocused at the hole exit by employing a reflective concave mirror lens. In this way, an additional ablation occurs at the hole exit to improve the hole accuracy. Especially, the exit size of the holes increases and simultaneously their cylindricity is improved while the tapering angle is reduced. Notably, these improvements are achieved without affecting the processing efficiency whereas the proposed laser drilling setup is relatively simple to implement

Bioprinting is a rapidly expanding additive manufacturing process, which offers a great potential for the fabrication of living tissue by precise printing of cells and biomaterials in a variety of substrates. Between the main bioprinting techniques, Laser Induced Forward Transfer (LIFT) offers the highest degree of spatial resolution, accurate and controlled deposition of bioinks and post-printing cell viability. In this study, a variety of cell-laden bioinks are printed mixed with different biomaterials to build ex vivo 3D structures, utilizing a Nd:YAG laser source at 532 nm wavelength, proving the ability to immobilize cells inside biomaterials in any desired depth.

Laser nanotechnologies have enormous potential for bringing products with new surface functionalities to market, while meeting sustainable development objectives. However, SMEs are not benefiting fully from these technologies because of their cost and the necessary access to testing and validation infrastructures. The Horizon 2020-funded NewSkin project has thus created an Open Innovation Test Bed (OITB) focused on surface nanotechnologies to overcome these challenges. It provides access to scale-up and testing facilities to enhance surface properties in different relevant sectors. Regarding laser nanotechnologies, NewSkin provides access to different laser up-scaling facilities that integrate innovative manufacturing processes, including surface texturing, roll-to-roll femtosecond laser texturing, heat-treatment laser, multi-modal laser processing. Several companies and research organisations have benefited from these technologies to improve surface functionalities such as wettability properties, improved heat exchange, friction reduction, wear resistance. The creation of NewSkin AISBL will accelerate the uptake of innovative laser processes to manufacture new nanoproducts.

Liquid-metal is a promising electrode material for soft electronics. In order to achieve controllable fine patterning of liquid-metal, superhydrophobic surfaces were fabricated on flexible substrate using a near-infrared ultrafast laser scanning. Cross-sectional SEM images of specimen of PDMS(polydimethylsiloxane) showed trapezoidal shapes with hierarchical micro/nanostructure. The laser-treated surface has super-hydrophobic properties and does not easily adhere to liquid metal. The PDMS surface was endowed with superhydrophobicity as well as supermetallicity by the microstructure induced by femtosecond laser. Using designed superhydrophobic surface, circuits from 40 to 100 m, microchannels with widths of 200 m and 400 m, and various designs were patterned. This method is fast, simple, inexpensive, does not require additional vacuum equipment, and is expected to be highly applicable, such as fabricating wearable devices, soft electronics.

In conventional photolithography, micro-nano pattern creation requires mask. However, using a Digital Micro Mirror Device (DMD) allows for the dynamically variable modulation of desired shapes, removing the need for masks. DMD-based mask-less photolithography systems use optical delivery systems to project images from the DMD, but this limits pattern resolution due to the Rayleigh criterion, leading to undesirable distortions in standard projection imaging systems. This study focuses on significantly improving pattern resolution in the depth of focus (DOF) direction by employing femtosecond laser-driven two-photon polymerization. We also examine the generation of micro-nano patterns by simulating the Point Spread Function (PSF) for compensating the distorted images produced through an optical system characterized by high magnification and diffraction-limited capabilities. Our research is dedicated to developing new methods for enhancing high-resolution digital patterning, moving beyond the limitations of conventional mask-based lithography techniques.

Chemical and topographical analyses were performed on ps-laser processed high spatial frequency laser-induced periodic surface structures (HSFL) on titanium alloy (Ti-6Al-4V) surfaces. Our multi-method approach involves scanning electron and atomic force microscopy, stylus profilometry, as well as hard X-ray photoelectron spectroscopy and depth-profiling time-of-flight secondary ion mass spectrometry. This allows to answer the questions how the laser processing of HSFL can be industrially scaled up, and whether the latter is limited by heat-accumulation effects.

We study laser-induced periodic surface structures (LIPSS) on an Al-based alloy manufactured by laser-based powder bed fusion of metals (PBF-LB/M). By employing a 780 nm wavelength, 30fs laser source with varied pulse shapes, fluence, and number of pulses, we examine the correlation between temporally shaped pulses and resulting surface morphology. The investigation reveals a connection between pulse shaping and the regularity of the imprinted structure, suggesting that controlling surface properties through unique pulse shapes can enhance the applicability of additively manufactured materials in specific domains such as optics, adhesive bonding, and friction reduction.

Fiber Bragg grating (FBG) inscription with femtosecond laser pulses has distinct advantages over conventional phase mask-based ultraviolet laser inscription methods, such as possibility to write FBGs in optical fibers made of almost any transparent material, inscription of high temperature stable FBGs, and through coating grating writing. However, femtosecond pulse inscription of FBGs also requires dealing with secondary effects that stem from the non-linear nature of the refractive index change, such as a pronounced birefringence and a substantial polarization-dependent loss (PDL). To decrease polarization dependent effects in FBGs and increase the reflectance, we developed a dedicated plane-by-plane FBG inscription recipe using a slit beam-shaping approach. With this method we demonstrate a series of 5 mm long highly reflective FBGs with ultra-low birefringence below 2E-6 and a record low PDL compared to previously reported femtosecond FBG.

Most future industrial applications of USP lasers require high processing quality, but also higher throughput and productivity, for example with higher average powers and more advanced processing strategies. We provide a description of a built-in functionality enabling synchronization of multiple mechanical and optical axis to enhanced engraving and texturing operation over 3D surfaces. Thanks to a closed loop regulation of the scanner over the mechanical axis encoder, the energy distribution is maintained constant and homogeneous during machining. The functionality is fully integrated into our software allowing us to easily generate complex machining with multiple input formats. Thanks to the simultaneous and synchronized motion between mechanical and optical axis, large machining areas can be processed without discontinuities in the pattern with a better thermal management of the process. This important aspect paves the way for increased productivity thanks to the increase of laser power and scanning speeds in industry. We provide a new solution for optimized cycle time and machining quality, demonstrated here onto parts with revolutionary geometry.

This study investigates the efficacy of a nanosecond passive Q-switch solid-state Tm:YAP laser (1.94µm) for silicon wafer dicing and ablation. Focusing on clean and efficient cutting, crucial for the wafer industry, we assess its potential for stealth dicing. Through controlled variations in fluence, we demonstrate the laser's precise capacity in shaping craters with diameters ranging from 10μm to 40μm and depths up to 13μm. Leveraging laser parameters such as a 1.94μm wavelength, 600pm linewidth, fluence up to 80 J/cm², and pulse durations in the nanosecond range, we achieve tailored control. Strategic selection of fluence and repetition rates optimizes crater depth and minimizes waste, crucial for effective dicing and ablation applications. Beyond fluence thresholds, nonlinear effects enhance the laser's performance, emphasizing its potential for semiconductor industry precision work

Our study introduces a new method for label-free super-resolved polarimetry on nanomaterials, compatible with in-situ analysis. Integrating Image Scanning Microscopy (ISM) with polarimetry techniques, we achieve remarkable resolutions down to 90 nm while acquiring polarization information. Overcoming limitations associated with fluorophores in challenging materials, our approach facilitates quantitative measurements of optical properties. Applied successfully to nanostructured surfaces created by femtosecond lasers and boron nitride nanotubes, our work showcases the versatility of this methodology.

The study interactions between tumor cells and lymph nodes (LNs), will be investigated with the development of complex cell structures in a microfluidic chip by Laser Induced Forward Transfer (LIFT) technique. The lymphatic system and LNs are an integral part of our adaptive immune system and many tumors exploit lymphatic vessels to spread and colonize downstream LNs. The complex cell structures will be realized by the printing of tumor organoids and the multilayer printing of 2D layers of LN cells, initially on ECM and other substrates, and ultimately inside a microfluidic chip.

This study introduces a cost-effective method for fabricating planar interdigitated proximity sensors using laser-induced graphene foam (LIGF) electrodes on flexible polyimide substrates. The technique utilizes low-cost visible semiconductor lasers for direct laser writing, eliminating the need for additional conducting materials. The LIGF planar capacitive sensor demonstrates effectiveness in proximity sensing for safety systems and applications in smart shelves and liquid level measurement. The sensor reliably detects human presence up to 170 mm away, showcasing its versatility for various home and industry uses.

Modern additive technologies that produce 3D products from metal powders using lasers are unique in terms of the possibility of obtaining new materials and complex parts with the required functional properties in one manufacturing cycle. Laser Powder Bed Fusion (L-PBF) technology makes it possible to greatly facilitate and accelerate the production of such products directly from their CAD (computer-aided design) models. The fundamentals of L-PBF technology provide a significant advantage both in the development of new materials and the manufacture of products from them. The investigation of the processes of forming metal matrix composites by laser-powder bed fusion is driven by the need to ensure stable and confident properties of L-PBF MMC materials and parts regardless of the equipment used. In this research, the fundamentals of the L-PBF process during in-situ manufacturing of MMC from dissimilar powders having different melting points and granulomorphometric properties are considered. Preliminary numerical simulations of thermal fields for different parameters of the L-PBF process on the powder mixture have been carried out.

Hematoxylin and Eosin staining in paraffin embedded tissue (H&E staining) is a widely used method in the incision dimension measurement. Since H&E staining requires complicated process and spends a lot of time, a direct measurement method based on an optical microscope (OM) is proposed to measure the incision dimensions. Moreover, a direct measurement method using optical microscope, an indirect measurement method based on H&E staining and three-dimensional (3D) size measurement based on laser scanning confocal microscope (LSCM) are presented and compared. It was found that the direct measurement method is a simple, fast, precise and efficient method for incision dimension measurement ablated by femtosecond laser on biological soft tissue surface.

The paper evaluates the feasibility of applying neural networks in additive manufacturing. specifically in optical monitoring and defect detection in laser direct metal deposition. The advantages and challenges are discussed, and a neural network for defect detection is developed, trained, and validated. An experimental stand was developed and the effectiveness of an algorithm for detecting the most common defects in laser direct metal deposition was demonstrated. Further possibilities for advancing laser direct metal deposition through the utilization of neural networks are explored.

Femtosecond lasers play a significant role in the industrial processing of metals, including tasks such as cutting masks, drilling foils, texturing molds, and engraving. This research explores methods for maximizing the removal rate of metals. The highest removal rate and best quality can be achieved using pulses shorter than 300 fs and optimal laser fluence. We also demonstrate the potential of femtosecond laser polishing of laser-machined surface, resulting in surface roughness well below Sa<1 µm. Examples to be showcased include manufacturing gratings for FIR spectroscopy, drilling stainless steel, deep engraving, and polishing dies for coin minting.

Nanophotonic devices, such as diffractive optics, metamaterials, and photonic crystals, largely employ periodic nanostructures to achieve their optical functions. The combination of Nano-opto-electro-mechanical systems (NOEMS) with periodic gratings and subwavelength metamaterials has enabled the tunability of some of these optical properties. Laser interference lithography (LIL) is a powerful flexible technique to produce high-resolution submicron periodic nanostructures (with periods down to λ/2) over large areas without the use of a mask. However, the interference pattern between the multiple overlapping coherent laser beams results in distortions at the edges, which must be removed in subsequent process steps to define the active optical region or aperture of the device. In this work, we present the novel concept of a laser interference lithography method combined with a secondary direct write or mask aligner lithography to define apertures of periodic sub-micron photonic features and metasurfaces together with microscale electromechanical features to fabricate NOEMS devices and diffractive optics, without relying on e-beam or stepper lithography.

Unraveling the emergence of spontaneous patterns on laser-irradiated materials has been a long-standing pursuit. Periodic surface structures manifest as a result of multiphysical coupling involving electromagnetics, nonlinear optics, plasmonics, fluid dynamics, and thermochemical reactions. Periodic surface structures result from multiphysical coupling: electromagnetics, nonlinear optics, plasmonics, fluid dynamics, and thermochemical reactions. Multi-shot ultrafast laser pulses generate stable periodic patterns influenced by disturbances and nonlinear saturation. Describing pattern growth requires a model with symmetry breaking, scale invariance, stochasticity, and nonlinear properties. Stochastic Swift-Hohenberg modeling replicates hydrodynamic fluctuations near the convective instability threshold in laser-induced self-organized nanopatterns. We demonstrate that deep convolutional networks can learn pattern complexity, connecting model coefficients to experimental parameters for specific pattern design. The model predicts patterns accurately, even with limited data, identifying laser parameter regions and predicting novel patterns independently.

We exploited known effects of surface plasmon polariton (SPP) coupling into structured surfaces to suppress Laser-induced Periodic Surface Structures (LIPSS) growing around a hole-shaped seed structure. Holes ranging from 200 nm to 1500 nm in diameter were first created in the surface of a fused silica sample and then irradiated with a single femtosecond laser pulse (800 nm, 30 fs). For small diameters, Type-I LIPSS, typically related to metallic materials, appeared around the seed structure. For seed diameters around the laser wavelength, where the SPP coupling is hindered, the LSFL-I vanished. For larger diameters, they reappeared accompanied by additional LSFL-II, which have perpendicular orientation and are typical for dielectrics. Selectively deactivating SPP contribution to LIPSS generation can help elucidate the underlying processes, which are still a matter of debate.

Laser-induced crystallization is a novel alternative to classical methods for crystallizing organic molecules but requires judicious choice of experimental parameters for the onset of crystallization to be predictable. This study investigated the impact of the laser repetition rate on the time delay from the start of the pulsed laser illumination to initiation of crystallization, the so-called induction time. A supersaturated urea solution was irradiated with near infrared laser pulses with an intensity of 1E14 W/cm2 while varying the repetition rate from 10 to 20 000 Hz. The optimal rate discovered ranged from 500 Hz to 1 kHz, quantified by the measured induction time (median 2-5 seconds) and the mean probability of inducing a successful crystallization event (5E−2 %). For higher repetition rates (5 kHz to 20 kHz), the mean probability dropped to 3E−3 %. The reduced efficiency at high repetition rates is likely due to an interaction between an existing thermocavitation bubble and subsequent pulses. These results suggest that an optimized pulse repetition rate can be a means to gain further control over the laser-induced crystallization process.

Femtosecond laser inscription is a unique approach to achieve non-conventional manufacturing of integrated photonic devices such as laser waveguides. Our approach relies on sensitized glasses containing both silver and Ytterbium ions. Laser inscription allows for the 3D-localized production of highly luminescent molecular silver clusters that support waveguiding architectures. We demonstrate efficient energy transfers from silver clusters to Ytterbium, allowing for background-free 3D-localized near-IR emission. Near-IR laser amplification under indirect pumping is demonstrated, depicting the localized creation of a hybrid laser gain medium involving silver clusters and Ytterbium ions as donor/acceptor pairs. Further work targets to demonstrate integrated laser behavior.

Understanding laser-induced plasma formation dynamics is pivotal for controlling the energy density deposited within the solid dielectrics during ultrafast laser material processing. Conventional numerical codes, however, fail to reproduce the propagation dynamics of tightly focused Bessel beams, which are widely used for stealth dicing. We adapted the massively parallel Particle-In-Cell (PIC) code EPOCH, incorporating background permittivity and Keldysh field- and impact-ionization modules. We compare numerical simulations to experimental results across various imaging diagnostics. Our simulations enabled the identification of the pivotal processes governing dense plasma formation and reproduced the high energy density experimentally observed.

Recent progress in the development of high-power mid-IR laser sources and the exciting laser driven physical phenomena associated with the irradiation of solids via ultrashort laser pulses in that spectral region are aimed to potentially create novel capabilities for material processing. In particularly, the investigation of the underlying physical processes and the evaluation of the optical breakdown threshold (OBT) following irradiation of bulk dielectric materials with Mid-IR femtosecond (fs) pulses has been recently presented. In this report, we will explore the conditions that generate sufficient carrier excitation levels on a dielectric material (SiO2) coated with an antireflective (AR) semiconducting film (Si) of variable thickness which leads to damage. Simulation results demonstrate that the reflectivity and transmissivity of the Si/SiO2 are coating thickness-dependent that can be employed to modulate the damage threshold of the substrate. The study is to provide innovative routes for material sizes that can be used for antireflection coating and applications in the Mid-IR region.

Ultrashort pulse (USP) laser processing has great potential for precise microfabrication. Toward higher quality and productivity, we have developed the data-driven USP laser processing in which process parameters can be controlled based on data such as in-process monitoring and artificial intelligence (AI) optimization. In this work, stable formation of laser-induced periodic surface structure (LIPSS) in nanoscale on transparent glass materials has been demonstrated by the data-driven UPS laser processing.

Real-time monitoring of the laser surface texturing is very important to maintain the process in control and identify any geometrical deviations of the surface features from their referenced/predefined values. In this research, a novel compact in-line/in-axis monitoring system is reported. The system employs light diffractometry principle to extract geometrical information about the laser generated surface topographies and thus to judge if the process is in control. A collimated white light is focused through the laser beam delivery sub-system that integrates beam deflectors and a telecentric lens onto the workpiece. Then, the reflected light from the textured surface is sent back through the same optical path to a spectrometer. As the collimated white light is diffracted by the periodic surface structures, only the 0-order diffracted light is reflected to the spectrometer. The reflected spectra are dependent on the periodicity, depth, and amplitude of the surface features as they diffract the focused white light beam. Thus, by capturing the spectra from fields processed under different conditions, especially one with zero focal offset distance (FoD) and others with a varying FoDs,

We report on the recording of the near and far field intensity beam profiles to train a convolutional neural network, which is aimed to online detect system aberrations of an ultrafast laser amplifier. We extend the state of the art by implementing a spiral phase plate to use the concept of phase diversity. It is found that the underlying optical field in amplitude and phase can be accurately revealed.

Laser Welding offers the industry many benefits but remains time-consuming and costly to optimize. Artificial Intelligence, if capable of generalizing from past experiences, could help. In this research, data from material characterization trials were repurposed to train an AI at predicting weld penetration based on setup, material, and process parameters.

This keynote presentation addresses the advantages, recent developments, and perspectives of laser processing with ultrashort laser pulses. A special focus is laid on the tailored structuring of thin films as well as the manufacturing and probing of sub-diffraction surface nanostructures – an ongoing race to extreme scales. Current limitations are identified and an outlook to future scaling perspectives will be provided.

Surface-enhanced Raman spectroscopy (SERS) is a widely recognized label-free analytical method for chemical and biological detection. This study investigates a cost-effective, scalable process for creating disposable thermoplastic SERS substrates. These substrates feature intricate multiscale topographies, including laser-induced periodic surface structures (LIPSS) and hierarchical structures (HS). The process involves femtosecond laser-enabled fabrication of metallic masters and subsequent replication on Cyclic Olefin Copolymer (COC) using hot embossing. Gold and/or silver coating on LIPSS enhances electromagnetic performance. A significant electromagnetic enhancement factor together with a very low limit of detection for methylene blue and 4-MBA was achieved. This approach holds promise for broader SERS applications in the food and agriculture sectors.

High repetition rate femtosecond lasers are commonly used for fabricating laser-induced periodic surface structures (LIPSS) over large areas at high processing speeds. Industrially relevant metals, like steel, experience thermal modifications at repetition rates beyond several hundred kilohertz. In this work, we fabricate low spatial frequency LIPSS (LSFL) on steel, varying pulse repetition rates from 10 kHz to 2 MHz. The study characterizes laser-structured areas and redeposited debris using SEM and μ-Raman spectroscopy. A simple heat dissipation model identifies repetition rate ranges associated with thermal modifications. Morphological changes and debris impact functional wetting behavior, offering insights for optimizing parameters in high repetition rate femtosecond laser materials processing.

Ice accretion on external aircraft surfaces due to the impact of supercooled water droplets can negatively affect the aerodynamic performance and increases fuel consumption and reduces operational capability. To prevent it, passive approaches based on superhydrophobic surfaces is postulated as a key property to prevent the condensation of water droplets on the surface and thus, delay ice formation. In this research, novel research progress on the correlation between superhydrophobic properties of hierarchical patterns on aluminum created by ultrashort laser pulses and the reduction of ice-adhesion is reported. Wettability performance of Hierarchical structures (HSs) was evaluated over the time to assess their wettability transition from hydrophilic to superhydrophobic and specific storage conditions were defined. The functional behavior of three HSs aluminum surfaces were assessed by several icing and de-icing cycles by a climate chamber able to simulate freezing weather. Differences in terms of amount of ice growth and mechanism of ice nucleation were found for the studied HSs surfaces.

External pulse compression offers the possibility to shorten the pulse duration of industrial grade femtosecond lasers from 300 to 500 fs well below 100 fs with an efficiency of typically 90%. We nvestigated the sub 100 fs regime for industrial laser micromachining processes. We show first results of a parametric study on ablation efficiency varying the pulse duration over 2 orders of magnitude, from 57 fs to 5 ps. We further characterize the micro-processing quality in terms of the surface roughness and the minimum achievable structure size for metals, semiconductors and glasses with an industrial grade Carbide laser from Light conversion at a wavelength of 1030 nm in combination with MIKS1 S pulse compressor from N2 Photonics (offering sub 100 fs pulses) and a high end Excelliscan galvo scanner from Scanlab for repetition rates from 80 kHz up to 1.2 MHz.

2D molybdenum disulfide (MoS2) is a promising material for the application in the flexible electronic, where large, uniform, crystalline films on flexible substrates are desired. . In this study, a method for increasing the crystallinity of polycrystalline MoS2 films on SiO2/Si and glass substrate deposited by plasma enhanced atomic layer deposition processed with femtosecond laser pulses (λ = 1030 nm, tp = 200 fs), in a ”cold” annealing process is presented. The laser fluence range varies from fmin = 3.0 mJ cm^−2 to fmax = 30.00 m J^-2 with scanning speeds from vscan,min = 1 mm s^−1 to vscan,max = 1000 mm s^−1, at a repetition rate of frep = 2000 kHz. The crystallization and the influence of the processing parameters on the film topography are analyzed in detail by Raman spectroscopy and scanning electron microscopy. Finally, the influence of the laser processing on the film resistivity is investigated.

Femtosecond laser welding of glass has numerous advantages, such as high mechanical resistance and high temperature tolerances without adding new material. In this context, an innovative way to join glass using a long focal lens of 100 mm has been developed. The advantages of using such a lens are clear: a drastic diminution of the thermal gradient and a slow thermal accumulation allowing crack free joining thanks to the larger focal volume, and a more robust process thanks to the long Rayleigh length. The study of the thermal accumulation process will be presented.

Laser-Induced Forward Transfer (LIFT) technology has been employed in this study to digitally integrate single-layer graphene pixels, as well as source and drain (S/D) metal electrodes, onto PDMS and Kapton PI flexible substrates. The target application was the development of a flexible Graphene Field Effect Transistor (GFET). We have showcased the direct integration of intact graphene pixels with lateral dimensions ranging from 40 to 200 μm in between the S/D electrodes using laser pulses. The structural integrity of the transferred pixels was confirmed via Raman spectroscopy and SEM and electrical measurements validated the mobility of pristine graphene.The demonstrated results highlight the use of LIFT for transferring low-dimensional materials providing a digital solution for addressing complex use-cases and applications in the field of electronics (GFETs).

Laser printing with structural colors arising from nanostructure-light interaction is emerging as a promising technology to address the problem of toxic compounds in conventional coloration methods. Up to date, the best-performing laser coloration techniques rely on ultrafast pulsed lasers. In this work, we introduce an approach for low-power, wide-gamut laser coloration on a pre-processed metamaterial of self-assembled nanoparticles. The metamaterial, with aluminum-coated polystyrene nanospheres, changes color through oxidation layer and deformation shape control, achieved using a focused CW laser with an average power of 10 mW. This approach achieves a 33k DPI resolution on a flexible substrate with the broadest color gamut reported.

3D laser nanoprinting based on multi-photon absorption (or multi-step absorption) has become an established commercially available and widespread technology. Here, we focus on recent progress concerning increasing print speed, improving the accessible spatial resolution beyond the diffraction limit, increasing the palette of available materials, and reducing instrument cost.

Biological discovery is a driving force of biomedical progress. With rapidly advancing technology to collect and analyze information from cells and tissues, we generate biomedical knowledge at rates never before attainable to science. Nevertheless, conversion of this knowledge to patient benefits remains a slow process. To accelerate the process of reaching solutions for healthcare, it would be important to complement this culture of discovery with a culture of problem-solving in healthcare. The talk focuses on recent progress with optical and optoacoustic technologies, as well as computational methods, which open new paths for solutions in biology and medicine. Particular attention is given on the use of these technologies for early detection and monitoring of disease evolution. The talk further shows new classes of imaging systems and sensors for assessing biochemical and pathophysiological parameters of systemic diseases, complement knowledge from –omic analytics and drive integrated solutions for improving healthcare.

We present the fabrication of transverse graphitic microelectrodes in a 500 micrometer thick synthetic diamond bulk by using pulsed Bessel beams. By suitably placing the elongated focal length of the beam across the sample thickness, the graphitic wires grow from the bottom surface up to the top during multiple shot irradiation. Their morphology and the relative micro-Raman spectra are studied as a function of the laser parameters in single pulse writing regime and burst mode regime, highlighting the advantage of the latter for obtaining with fs pulses, low resistivity electrodes. We show that the crystallographic orientation of the sample also plays an important role in eliminating the potential barrier height of the IV curves. By optimizing the writing parameters, we generated high conductivity and homogeneous microelectrodes (with resistivity lower than 0.015 Ohm cm), which are crucial for the application of electric fields or current transport/collection in various chips and detectors.

We demonstrate how the implementation of an axicon-lens doublet configuration can lead to an efficient beam-shaping solution for laser-material processing with high-angle Bessel-like beams. Using ultrashort laser pulses at 1550 nm, we study the dynamics of elongated microplasmas, and high-aspect-ratio permanent modifications generated inside silicon. The results are discussed in regard to new modalities to fabricate optical and electrical through-silicon-vias.

Ultrafast higher-order Bessel beams have diverse applications, including creating high aspect ratio nanovoids and efficient glass cutting. This study introduces a novel method using higher-order Bessel beams to generate high-aspect ratio nanostructures vertically standing on sapphire with a single ultrafast laser pulse. The elongated nano-pillars exceed 15 μm in height and possess a sub-micrometer diameter. We propose a mechanism that explains the different generation regimes. Depending on deposited energy density, either material translation or hydrodynamics occur and produce different morphologies. Our conclusions are supported by transmission electron microscopy. This approach, applicable to various transparent materials, stands out for its simplicity and deepens understanding of ultrafast laser-material interactions, holding potential for advanced material processing.

Recently, the ultrafast Bessel beam has emerged as an efficient tool to structure nano-volumes in sapphire crystals with a high aspect ratio of more than 100. To increase the controllability of the process, there is a quest to understand better the interaction of ultrafast Bessel beams with sapphire in intensity ranges pertinent for nanostructuring. In the present study, we investigate the ultrafast interaction of a short-pulsed Bessel beam with a single-crystal sapphire sample using time-resolved phase contrast and quantitative phase contrast microscopy techniques. The time-resolved relaxation dynamics reveal that the plasma phase in sapphire persisted for the duration of a few ns followed by the tens of ns long hot phase that triggers amorphisation. Around 100 ns the manifestation of nano-volume expansion becomes visible. This study contributes to attaining precise control in the laser processing of sapphire for scientific and industrial applications.

Over last decade, ultrafast lasers became industrially viable tool for high precision material processing. Ability to modify in the bulk of transparent materials is one of unique attributes of this technology. This have been successfully used for glass cutting, implementation of photonic circuits and microfluidic chips, local engineering of optical fibre properties. This talk will explore how ultrafast lasers can be used to engineer optical scattering systems. The exploitation of this process for developing low loss distributed sensing systems and compact optical spectrometer will be discussed and demonstrated.

In recent years, Volume Bragg gratings (VBGs) have seen widespread use, traditionally inscribed in photo-thermo-refractive glasses. The emergence of femtosecond lasers has enabled VBG inscription in various materials. Silver-containing glasses have drawn attention due to their ability to produce strong Type-A (“A” for Argentum) refractive index changes. We explored the laser writing processes for optimizing the recording inscription of Type-A VBGs. The Gaussian-Bessel beam is employed to produce a single plane grating with 6700 µm3/s throughput while the phase mask approach is investigated to accelerate VBG inscription, allowing record throughput up to 106 µm3/s, paving the way for industrial applications.

Femtosecond laser 3D printing has revolutionized photonics by enabling the creation of intricate optical components. Our study introduces a high-precision waveguide Bragg grating sensor, crafted using the Femtoprint system's femtosecond laser. This technology allows for the direct writing of Bragg gratings in transparent substrates, offering precise control over geometry and sensitivity. Characterization demonstrates exceptional temperature sensitivity (10.51 pm/°C) and mechanical strain sensitivity (1.22 pm/µε). The femtosecond laser printing and Bragg grating technology opens new avenues, showcasing unique sensor capabilities and fostering interdisciplinary collaborations for future developments.

Fiber Bragg Gratings (FBGs) are widely used for sensing applications, particularly in harsh environments. More specifically, type III femtosecond (fs) FBGs, corresponding to a periodic structure of micro-voids and generated in silica-based optical fibers, show a prominent interest due to their ability to withstand very high temperatures (over 1000°C). Those structures, fabricated using the Point-by-Point (PbP) technique, were characterized using Quantitative Phase Microscopy (QPM), Raman spectroscopy and Transmission Electron Microscopy (TEM). Both the micro-voids and the surrounding densified shells were monitored under isochronal annealing experiments up to 1200°C.