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Bursts of GHz repetition rate pulses can significantly improve the ablation efficiency of femtosecond lasers. Depending on the process conditions, thermal mechanisms can be promoted and controlled. GHz ablation therefore combines thermal and non-thermal ablation mechanisms. With an optimal choice of the burst duration, the non-thermal ablation can be highly enhanced by a heating phase due to the first pulses in the burst. The GHz burst mode can be considered as a key function for the “agility” of new high-power lasers.

We report on high aspect ratio and high-speed glass drilling with femtosecond GHz-bursts. The drilling process dynamics of deep and high-quality holes in different glasses and sapphire is monitored by in-situ microscopy and thermal imaging.

Nowadays the relevance and the robustness of ultrafast lasers are well established for many industrial applications. The main limitation to the penetration of femtosecond processing in the industrial manufacturing market is the insufficient productivity compared to the needs of the application markets and alternative technologies. Increasing the power, pulse energy or repetition rate, of femtosecond lasers has been a general trend in in order to comply to the needs of the market for higher throughput. One of the strategies of increasing the power has resulted in the development of a GHz femtosecond laser. When increasing the repetition rate during the process beyond several hundred kHz, the delay between the laser pulses is less than the thermal relaxation time and there is thermal accumulation in the target material. The resulting rise in temperature leads to an ablation threshold lowering. The authors report on a simple and easy-to-use GHz amplified femtosecond laser source. The laser source is based on a passively mode-locked oscillator with a near GHz repetition rate. GHz pulses are then selected, and the obtained bursts of pulses are further amplified in a high-power amplifier chain. The presented GHz femtosecond laser source is used with a galvanometric scanner to perform ablation experiments on copper, aluminum, and stainless steel. Specific ablation rates of 0.7, 2.3, and 1.4 (mm3/min)/W are reached. The role of the important experimental parameters, such as the number of sub-pulses in the burst, is highlighted. Thanks to a specific ablation scheme in the GHz mode, the ablation efficiency is then comparable to the case of single nanosecond pulses, but with the usual quality of femtosecond processing.

We report on a 100-fs GHz burst laser with up to 100-W average output power. This laser is based on a Tangor femtosecond laser with GHz burst option followed by nonlinear pulse compression in a gas-filled hollow core Kagome fiber. Combining pulse compression with hollow core fiber transport is an attractive extension for industrial femtosecond lasers. Laser ablation of metals, silicon, and sapphire have been performed with this new laser source in order to study the impact of the ultrashort pulse duration on the laser matter interaction with GHz bursts.

We report on the first industrial UV femtosecond laser with more than 100W average output power. The laser is ideally suited for high throughput precision applications, in particular for glass and polymer cutting in display industry. Thanks to its flexibility in pulse repetition rate, pulse energy, and free triggering at constant pulse energy, the femtosecond UV laser can be used in parallel processing with multiple beams as well as in high speed scanning applications, e.g. with polygonal scanners. The femtosecond pulse duration after frequency conversion to UV can be substantially reduced compared to the 400-fs pulse duration high power laser at the fundamental wavelength of 1030nm.

We report on a kilowatt femtosecond laser with the high precision triggering function FemtoTrig® and flexible burst shapes. The high power femtosecond laser is based on a multi-stage hybrid fiber-crystal based Innoslab amplifier platform and chirped pulse amplification. The kilowatt femtosecond laser is foreseen to serve in high throughput applications integrating multiple beams generated by diffractive optical elements (DOEs) and allowing individual pulse control of the multiplexed beamlets via multi-channel acousto-optical modulators.

We report on kW femtosecond lasers that will enable large scale and high productivity industrial applications. Power scaling is achieved by an Innoslab amplifier followed by slab-based booster amplifier stages. The laser concept is capable to generate high pulse energies in the multi-mJ range as well as high pulse repetition rates in the MHz or GHz ranges. Moreover, free triggering (FemtoTrig®) and burst options as well as frequency conversion to the green and UV spectral region will leverage these femtosecond lasers into future industrial applications. Also in the scientific domain these lasers will have a strong impact, e.g. as pump sources for powerful OPAs or high harmonics generation at high photon flux.

International audience

The 4F consortium has obtained new results on microstructured optical fibers for the development of Ytterbium active fibers with a large core but also of hollow fibers for the transport of the laser beam. The active fiber core composition aims to ensure good performance in aging and photodarkening. The fiber specifications are a Mode Field Diameter greater than 30 μm, a Polarization Extinction Ratio more than 15 dB, a cladding absorption at 976 nm more than 10 dB/m, bending over a relatively small diameter (about 20cm). The fiber will allow a laser operation exceeding 150 W.

Based on a simplified ablation model using only two parameters to describe a material, we have developed a numerical method of inverse computation to obtain the most judicious laser configurations for a given depth of ablation in a given material. The calculations are carried out for more than one million configurations (pulse energy, pulse rate, spot diameter, scan speed, …). The results are stored and analyzed on demand via multiple input tables. The digital tools are validated for stainless steel, and ablation results will also be presented for other metals (aluminum, titanium) or composite materials (CFRP).

Hybrid femtosecond lasers today deliver output powers of several hundred watts. Translating the available power into high-speed micromachining requires new approaches such as beam delivering tools with suitable synchronization of the laser pulses. We study the interest of rapid scanning systems or multi-beam shaping but also a rapid estimation of the ablation efficiency using a simple engineering model.

We present a high-power femtosecond GHz burst laser with nonlinear frequency conversion to the ultraviolet spectral region. An average power as high as 20-W at 343nm wavelength has been obtained after third harmonic generation of a 100-W, 480-fs GHz burst mode femtosecond laser at 1030nm. This is to our knowledge the first demonstration of a high-power ultraviolet femtosecond laser with GHz bursts. GHz femtosecond lasers have recently revealed significant interest for micro-machining applications, in particular by showing substantially increased ablation efficiencies on different materials [1, 2]. Frequency conversion to the ultraviolet spectral region is highly interesting for spatial and chemical selectivity in multi-material or multi-layer material processing, especially for materials containing organic components. Our high-power UV femtosecond GHz burst laser is therefore promising for high efficiency and high-quality laser processing of polymer-based materials with low heat affected zones.

We report on silicon ablation with a 20 W GHz amplified femtosecond laser source. This novel laser delivers burst energies up to 400 μJ, providing flexible intra-pulse repetition rates of 0.88 or 3.52 GHz, up to 200 pulses with ∼350 fs pulse duration. High-efficiency, high-quality ablation can be achieved through optimally determining the number of pulses, intra-pulse repetition, and average pulse energy within a burst. Due to such optimization, we demonstrate a specific ablation rate of 2.5 mm3/min/W with a burst containing 200 pulses at 0.88 GHz, which is the highest one reported so far for fs laser ablation, to the best of our knowledge. GHz ablation is sensitive to the selection of laser parameters. We conceptually discuss the contributions of the pulses within a burst to heat-accumulation-based incubation and material ablation.

Translating the high available power for current industrial lasers in the 100 to 500 W range into high throughput micro-processing is of high importance for future industrial applications. High repetition rates and/or high energies can lead to detrimental thermal effects on the sample and degrade the process quality even using ultrafast lasers. New processing strategies are therefore required to take full advantage of the laser available power. Programmable spatial light modulators (SLM) can bring flexibility while maintaining a high spatial resolution compatible with complex optical functions like multi spots or user defined beam profiles. They enable specific laser characteristics, that can change during the process. The recent technological progress in LCOS based systems, enables high optical transmission greater than 95 %, but also high average power handling up to at least 100 W of laser power. However, the dependence of SLM shaping performance on laser bandwidth places specific requirement when using ultrafast lasers. We will present phase map optimization strategies dedicated to specific industrial applications.

We report on a flexible ultrafast thin-disk laser system delivering sub-1ps pulses at 1kW of average power. To enable high-throughput material processing a fast modulation scheme based on polarization-multiplexing and a burst-mode operation were implemented.

We present a high-power70W, sub-50fs, 400µJ source at 200 kHz. This source is based on the high-efficiency nonlinear compression of an industrial grade 100 W, 450 fs amplifier through a gas-filled multipass cell (MPC) scheme.

We report on crater formation, line scribing and cavity milling experiments on Silicon, Copper, Aluminum and stainless steel with GHz bursts of femtosecond pulses. The intra-burst repetition rate has been varied between 0.88 and 3.52 GHz, the number of pulses per burst between 50 and 3200, the burst fluence between 8 and 80 J/cm2. For these experiments, a 100-W femtosecond GHz-burst laser has been developed on an industrial laser basis, delivering a total burst energy up to 1 mJ at 100 kHz, with an adjustable number of pulses per burst. The results highlight the conditions to obtain high-ablation efficiency, show how to optimize the machining quality and point out the burst duration as the relevant parameter for femtosecond GHz machining.

We report on a kW-class ultrafast laser amplifier emitting sub-300 fs pulses with a pulse peak power exceeding 1 GW. It is based on the direct amplification of 260 fs pulses in a versatile thin-disk multipass amplifier which provides fast modulation of the amplified beam on the workpiece by the implementation of a novel and robust polarization multiplexing scheme for the seed beam that is launched into the amplifier. Furthermore, the laser can be operated in a single-pulse or burst mode with a variable number of pulses per burst. Second harmonic conversion of the amplified beam by means of a lithium triborate crystal additionally led to an output power of up to 282 W in the green spectral range.

Nowadays the relevance and the robustness of ultrafast lasers are well established for many industrial applications. Indeed this laser technology combines the unique capacity to process any type of material with an outstanding processing precision and a minimal heat affected zone. The key issue is to combine high throughput, low residual thermal load and good processing quality. Thanks to high average power and high repetition rate it is possible to achieve high throughput providing that the operating parameters are precisely tuned to the application, otherwise heat accumulation and heat affected zone may appear, leading to detrimental effects such as burr, uncontrolled melting and metal oxidation. In this paper we report on high-throughput laser ablation of metals using a 100W- and 10MHz- ultrafast laser. Target materials were stainless steel, Copper, and Aluminum. Operating parameters such as fluence, repetition rate and scanning velocity have been considered. Results are discussed in terms of ablation efficiency, surface morphology, multipass and upscaling capabilities. Different behaviors between materials are also discussed. We observe that pulse-to-pulse pitch and delay are key parameters that must be taken into account in order to define relevant process windows for each material. The use of polygon scanner instead of galvo scanner enables us to reduce the thermal load along the laser trajectory. The point is not to avoid heat accumulation but to take advantage of this phenomenon as long as the target material can stand the thermal load without detrimental effects on the processing quality.

250 fs and several μΐ UV laser-pulses at 343 nm were spectrally broadened 20-fold and compressed down to 50 fs using gas-filled Inhibited-Coupling hollow-core photonic crystal fiber with optimized dispersion and Kerr optical nonlinearity.

International audience; —We present a numerical and experimental analysis of a nonlinear architecture to overcome the gain bandwidth limitation in regenerative amplifiers. This technique is based on the optimization of dispersion and nonlinear effects during the amplification process to obtain broad-bandwidth pulses that can be compressed to short durations with high temporal quality. We demonstrate the advantage of this method to maintain an excellent temporal quality of pulses even at high levels of optical nonlinearity. The technique has been applied to regenerative amplifiers using Yb:YAG, Yb:KYW, and Yb:CALGO crystals as gain media. In all cases we achieved the shortest pulse duration ever obtained from regenerative amplifiers using the respective laser crystals. These results underline the benefits of this amplification technique with respect to current state of the art.

The vast majority of HHG sources are nowadays driven using Ti:Sapphire lasers that typically generate 30 fs pulses with few mJ energy at 1 kHz repetition rate and 800 nm wavelength, corresponding to average powers limited to around 10 W. Nonlinear compression of these sources leads to the few-cycle regime with pulse durations below 5 fs [1]. Nowadays another approach is to use femtosecond rare earth-doped fiber amplifiers that are capable of generating kW average powers [2]. In this case, gain narrowing limits the pulse duration of high energy fiber CPA to above 250 fs, and accessing the few-cycle regime requires two stages of nonlinear compression [3].

Nowadays processing of transparent materials, such as glass, quartz, sapphire and others, is a subject of high interest for worldwide industry since these materials are widely used for mass markets such as consumer electronics, flat display panels manufacturing, optoelectronics or watchmaking industry. The key issue is to combine high throughput, low residual stress and good processing quality in order to avoid chipping and any post-processing step such as grinding or polishing. Complimentary to non-ablative techniques used for zero-kerf glass cutting, surface ablation of such materials is interesting for engraving, grooving as well as full ablation cutting. Indeed this technique enables to process complex parts including via or blind, open or closed, straight or small radius of curvature patterns. We report on surface ablation experiments on transparent materials using a high average power (70W) and high repetition rate (1 MHz) femtosecond laser. These experiments have been done at 1030nm and 515nm on different inorganic transparent materials, such as regular and strengthened glass, borosilicate glass or sapphire, in order to underline their different ablation behavior. Despite the heat accumulation that occurs above 100 kHz we have reached a good compromise between throughput and processing quality. The effects of fluence, pulse-to-pulse overlap and number of passes are discussed in terms of etch rate, ablation efficiency, optimum fluence, maximum achievable depth, micro cracks formation and residual stresses. These experimental results will be also compared with numerical calculations obtained owing to a simple engineering model based on the two-temperature description of the ultrafast ablation.

With the development of high average power, high repetition rate, industrial ultrafast lasers, it is now possible to achieve a high throughput with femtosecond laser processing, providing that the operating parameters are finely tuned to the application. Femtosecond lasers play a key role in these processes, due to their ability to high quality micro processing. They are able to drill high thickness holes (up to 1 mm) with arbitrary shapes, such as zero-conicity or even inversed taper, but can also perform zero-taper cutting. A clear understanding of all the processing steps necessary to optimize the processing speed is a main challenge for industrial developments. Indeed, the laser parameters are not independent of the beam steering devices. Pulses energy and repetition rate have to be precisely adjusted to the beam angle with the sample, and to the temporal and spatial sequences of pulses superposition. The purpose of the present work is to identify the role of these parameters for high aspect ratio drilling and cutting not only with experimental trials, but also with numerical estimations, using a simple engineering model based on the two temperature description of ultra-fast ablation. Assuming a nonlinear logarithmic response of the materials to ultrafast pulses, each material can be described by only two adjustable parameters. Simple assumptions allow to predict the effect of beam velocity and non-normal incident beams to estimate profile shapes and processing time.

Surface functionalization is a rapidly growing application for industrial ultrafast lasers. There is an increasing interest for high throughput surface processing, especially for texturing and engraving large manufacturing tools for different industrial fields such as injection molding, embossing and printing. Hydrophobic and hydrophilic surfaces, colored or deep black metal surfaces can now be industrially produced. The engraving speed is continuously improving following improvements in beam scanning technology and high average power industrial ultrafast lasers. Several tenths of MHz for the laser repetition rate and several hundreds of meter per second for the beam speed are available. More than 100 m/s scanning speed is then possible for laser surface structuring. But these surfaces are quite hard to produce since it is necessary to have a good compromise between high removal rate and high surface quality (low roughness, burr-free, narrow heat affected zone). In this work, we apply a simple engineering model based on the two temperature description of ultra-fast ablation to estimate key processing parameters. In particular, the pulse-to-pulse overlap which depends on the scanning velocity, the spot size, and the laser repetition rate all have to be adjusted to optimize the depth and roughness, otherwise heat accumulation and heat affected zone may appear. Optimal sequences of time and spatial superposition of pulses are determined and applied with a polygonal scanner. Ablation depth and processing speed obtained are compared with experimental results.

International audience; A simple, compact, and efficient few-cycle laser source at a central wavelength of 1 µm is presented. The system is based on a high-energy femtosecond ytterbium-doped fiber amplifier delivering 130 fs, 250 µJ pulses at 200 kHz, corresponding to 1.5 GW of peak power and an average power of 50 W. The unprecedented short pulse duration at the output of this system is obtained by use of spectral intensity and phase shaping, allowing for both gain narrowing mitigation and the compensation of the nonlinear accumulated spectral phase. This laser source is followed by a single-stage of nonlinear compression in a xenon-filled capillary, allowing for the generation of 14 fs, 120 µJ pulses at 200 kHz resulting in 24 W of average power. High-harmonic generation driven by this type of source will trigger numerous new applications in the XUV range and attosecond science.

We demonstrate the beneficial effect of femtosecond bursts for energy concentration during volume processing of transparent material. By single pulse energy redistribution in burst sub-pulses, nonlinear effects can be significantly reduced. A 25 ns time delay between sub-pulses leads to temperature high enough to induce in-volume crack. These cracks can be controlled to obtain high speed and high quality glass cutting.

International audience; We demonstrate the advantage of combining non-diffractive beam shapes and femtosecond bursts for volume laser processing of transparent materials. By redistribution of the single laser pulse energy into several sub-pulses with 25 ns time delay, the energy deposition in the material can be enhanced significantly. Our combined experimental and theoretical analysis shows that in burst-mode detrimental defocusing by the laser generated plasma is reduced, and the non-diffractive beam shape prevails. At the same time, heat accumulation during the interaction with the burst leads to temperatures high enough to induce material melting and even in-volume cracks. In an exemplary case study, we demonstrate that the formation of these cracks can be controlled to allow high-speed and high-quality glass cutting.

The authors report on a simple and easy-to-use GHz amplified femtosecond laser source. The laser source is based on a passively mode-locked oscillator with a near GHz repetition rate. GHz pulses are then selected, and the obtained bursts of pulses are further amplified in a high-power amplifier chain. The presented GHz femtosecond laser source is used with a galvanometric scanner to perform ablation experiments on copper, aluminum, and stainless steel. Specific ablation rates of 0.7, 2.3, and 1.4 (mm3/min)/W are reached. The role of the important experimental parameters, such as the number of subpulses in the burst, is highlighted. Thanks to a specific ablation scheme in the GHz mode, the ablation efficiency is then comparable to the case of single nanosecond pulses, but with the usual quality of femtosecond processing.The authors report on a simple and easy-to-use GHz amplified femtosecond laser source. The laser source is based on a passively mode-locked oscillator with a near GHz repetition rate. GHz pulses are then selected, and the obtained bursts of pulses are further amplified in a high-power amplifier chain. The presented GHz femtosecond laser source is used with a galvanometric scanner to perform ablation experiments on copper, aluminum, and stainless steel. Specific ablation rates of 0.7, 2.3, and 1.4 (mm3/min)/W are reached. The role of the important experimental parameters, such as the number of subpulses in the burst, is highlighted. Thanks to a specific ablation scheme in the GHz mode, the ablation efficiency is then comparable to the case of single nanosecond pulses, but with the usual quality of femtosecond processing.

Ultrashort pulse lasers have been established as precise and universal tools for the micromachining of solid materials (cutting, texturing …). For these applications the quality of the cutting cross-section is important. The use of a Gaussian beam profile and linear polarization leads to tapered cutting sidewalls. It is possible to change the polarization orientation in order to machine a material for obtaining straight and vertical sidewalls. For this purpose a specific polarization converter was used. The transformation of the polarization distribution from linear to radial and azimuthal is done by a subwavelength, binary grating creating a π phase shift between the TE and TM transmitted waves. In this paper we report on investigations on the influence of laser polarization (radial, azimuthal, circular, linear) on the ablation characteristics of molybdenum and PZT using an Yb doped crystal laser (500 fs) and compare these results with previously published results.

International audience; A hybrid-system approach using a low-gain Yb:YAG single crystal booster amplifier behind a state-of-the-art industrial high-power femtosecond fiber system is studied to significantly increase the output pulse energy of the fiber amplifier. With this system, more than 60 W of average power is demonstrated at 100 kHz for pulse duration of 400 fs, corresponding to an energy per pulse of 600 µJ. Reducing the repetition rate, the energy is increased up to 2.5 mJ (before compression), which corresponds to the limitation due to laser damage threshold of the optical coatings. To scale further the energy, passive divided-pulse amplification is then implemented at the entrance of the bulk amplifier. Using this geometry, a safe nominal operating point is presented with output pulse energies of 3 mJ before and 2.3 mJ after compression and with a pulse duration of 520 fs, corresponding to a peak power of 4.4 GW.

International audience; A hybrid ytterbium-doped fiber – bulk laser source generating up to 116MW peak power for 3ps pulse duration at 50kHz repetition rate and 1030nm wavelength is presented. Tunability of the pulse duration is made by spectral compression occurring into the seeder. Divided Pulse Amplification scheme is investigated to study energy capabilities of the setup.

We report the generation of 10 μJ, ultrashort 97 fs pulses at 1 MHz by implementing a two-arm spectral coherent combining scheme in a fiber chirped-pulse amplifier (FCPA), allowing both gain-narrowing mitigation and large stretching ratio for energy extraction. Such architecture is able to support the amplification of large-bandwidth (>15 nm) together with high gain factor (>30 dB), allowing the generation of ultrashort sub-100 fs pulses at the output of a FCPA for the first time.

Glass cutting is a subject of high interest for flat panel display and consumer electronics industries. Among laser-based, water jet-based and diamond tool-based existing solutions, ultra-short pulses (USP) appear as a promising technology since this laser technology has the unique capacity to produce highly localized bulk modification owing to non-linear absorption. The cutting using USP lasers could be performed either by full ablation which is slow and generates a lot of dust, by controlled fracture propagation which is slow as well and may lead to path deviation, by stealth dicing which produces rough sidewalls, or by self-breaking induced by in-volume laser irradiation. The laser treatment is often continuous which is not necessary to perform glass cutting and may lead to over-exposure. In this paper we report on single pass glass and sapphire cutting using an USP laser (20W @200kHz or 8W@2MHz) using dash line laser treatment along the cutting trajectory. In-volume energy deposition was done along the glass thickness owing to a Bessel beam. The results will be discussed in terms of sidewall profile and roughness, path deviation, rim sharpness, energy dose and feed rate. Dash line treatment enables to tune the energy deposition and to produce the cutting effect but with a narrower heat affected zone, a better sidewall quality and a more accurate trajectory control of the cutting path.

We present an engineering model of ultrafast laser ablation, and apply it to the drilling and trepanning injection nozzles with non normal incidence beams, a key industrial process in the automotive industry.

Hybrid ytterbium-doped fiber/Yb:YAG-bulk laser source generating pulse in duration from 3 ps to 20 ps is reported. 116 MW peak power is demonstrated for 3-ps pulses with employment of divided pulse architecture generating 4 temporal replicas.

In this work we study glass welding by ultrashort laser pulses. We evaluate the influence of the residual mechanical stresses due to the welding process of the borosilicate glass on the assembly strength and resistance to mechanical strain. Sample characterization is performed thanks to a three-point bending test and cross polarization optical microscopy. Welding regimes with and without heat accumulation are considered. The wavelength and pulse duration of the laser used in this study are 1030nm and 350 fs respectively. The influence of pulse energy (0.8µJ to 1.2µJ), repetition rate (100 to 500kHz), focusing condition and laser trajectory is discussed in terms of mechanical resistance and of the extent of the residual mechanical stresses.In this work we study glass welding by ultrashort laser pulses. We evaluate the influence of the residual mechanical stresses due to the welding process of the borosilicate glass on the assembly strength and resistance to mechanical strain. Sample characterization is performed thanks to a three-point bending test and cross polarization optical microscopy. Welding regimes with and without heat accumulation are considered. The wavelength and pulse duration of the laser used in this study are 1030nm and 350 fs respectively. The influence of pulse energy (0.8µJ to 1.2µJ), repetition rate (100 to 500kHz), focusing condition and laser trajectory is discussed in terms of mechanical resistance and of the extent of the residual mechanical stresses.

We present an engineering model of ultrafast laser ablation with normal or non-normal (oblique) laser beams. It can be applied to trepanning drilling but also to zero-taper cutting. Specific experiments on line ablation are presented to understand how oblique beams can control the walls conicity. Industrial strategies for processing with high throughput and high quality are considered.

Industrial ultrafast lasers are a key component of many new industrial manufacturing processes. The virtually athermal nature of the laser–matter interaction process enables high-quality material processing for many different materials with feature size reaching into the nanometer scale. Advances in laser average power and beam-delivery technology have significantly improved the throughput and productivity of real-life industrial and medical applications. In this article, we present key examples of laser processing, including drilling, cutting, and surface processing. In particular, we describe how ultrafast lasers can improve vision in patients, extend battery lifetime, improve the efficiency of solar cells and infrared detectors, or be applied in the printing or microelectronics industries. These examples demonstrate how further developments rely on a combination of laser technology, beam handling and delivery, and laser–matter interaction processes.

Resume Nous presentons un bilan du projet NOUGAT qui a ete finance dans l’edition 2008 du programme TecSan de l’Agence nationale de la recherche. Le projet vise a la conception et a la realisation d’un dispositif innovant de chirurgie oculaire par laser a impulsions ultrarapides pour la chirurgie du glaucome assistee par un systeme d’imagerie in situ. Les avancees significatives obtenues au cours du projet sont entre autres la realisation d’une source laser a impulsions ultrabreves puissante et compacte dont la longueur d’onde d’emission est adaptee a la transparence de la sclere et le developpement d’un systeme d’imagerie optimise base sur la tomographie par coherence optique.

The Femtoprint project, a European project, aims at demonstrating the use of low-energy laser pulses (i.e. below the ablation threshold) to manufacture monolithically integrated devices including optofluidic, optomechanical and photonic devices. The longer-term objective is the implementation of a versatile table-top machining center. This paper summarizes the project progress to date and demonstrates the potential of this approach through various illustrative examples.

Pico and femtosecond lasers present a growing interest for industrials applications such as surface structuring [1] or thin film selective ablation [2]. Indeed, they combine the unique capacity to process any type of material (dielectrics, semiconductors, metals) with an outstanding precision and a reduced affected zone. We report on results about surface engraving of metals (Al, Cu, Mo, Ni), semiconductor (Si) and polymer (PC) using a picosecond thin disk Yb:YAG-amplifier. The pulse duration of this source can be changed using two different configurations: direct amplification of a 34ps-oscillator on one hand, and 1ps-chirped pulse amplification (CPA) scheme on the other hand. The results obtained with this thin disk laser are compared to ones achieved with two commercial femtosecond lasers respectively based on Yb-doped crystals and fibers, and operating at similar output power levels (up to 15Watt).