Project: Flexible and Robust processing Units based on Innovative amplification Techniques of Fiber Ultrashort Lasers

Material processing with high-energy ultrafast (femtosecond) laser pulses is a fast growing technique for precise micro-machining of a variety of materials, e.g. ceramics, metals, polymers etc... Although generally considered as the technology that permits the achievement of unprecedented performances in terms of laser cutting, drilling, scribing, etc, it is still often noticed as being complex and unreliable, especially in industrial environment. Thus, such sources are today slowly entering industry and are still facing some limitations related to cost, size and stability. _x000D__x000D_The CO reasons for the above mentioned limitations are related to two particular technical aspects:_x000D_1) the difficulty to generate stable and reliable ultrashort pulses, _x000D_2) and in particular the difficulty to handle a high peak power amplification. _x000D__x000D_Concerning ultrashort pulses generation, the most usual way consists in using semiconductor saturable absorbers. It is a well established and masterized technique by the Ps of the project, in particular LZH and Multitel, but long term operation and reliability is still not mature enough for a future industrial application. Various solutions can be implemented for improving the lasers long term stability. These solutions rely mostly on the association of mechanics, optics and electronics for monitoring the laser operation and counter-reacting on the laser cavity._x000D__x000D_Concerning amplification, one usual way to deal with high peak powers in fiber-based systems is using the classical chirp pulse amplification (CPA) scheme. The CPA technique is based on temporal broadening of the pulses prior to amplification to avoid too high peak powers and recompressing the pulses after amplification to recover the original pulse duration. Another mean is based on regenerative amplifiers (RegAmp), in which a single pulse is coupled into a resonator, amplified by several roundtrips within an active crystal and then out- coupled by an optical switch using e.g. a pockels cell. This leads to the necessity of applying and integrating many additional components with the consequence of complex, susceptible and expensive set-ups. In our project we want to develop a CPA-free method based on single pass amplification through a combination of different active crystals. _x000D__x000D_Thus our project is dedicated to the development and realization of a unique and novel high energy femtosecond laser source which is competitive and viable in industrial manufacturing, avoiding the classical techniques and related drawbacks described above._x000D_In order to validate our technology and to give visibility to our results we plan to develop two demonstrators based on one common ultrafast laser front-end in order to address two different application fields:_x000D__x000D_1) a first fiber master-oscillator- power-amplifier (MOPA)-system will be used as front-end of an optical parametric generator (OPG) and amplifier (OPA) for the generation of mid-infrared radiation between 3 and 4 µm (achieved by P LASERSPEC). This laser source will be used for processing of flexible polymers (by P OPTEC). For this laser we will aim at demonstrating 100 µJ per pulse with a duration of about 5 ps (20 MW peak power) at 1064 nm and 10 µJ per pulse at 3.5 µm. _x000D__x000D_2) a second MOPA system with about 500 fs pulse duration, up to 20 µJ output energy at a repetition rate of 100 kHz will be combined with a second harmonic generator emitting in the visible at a wavelength around 532 nm. This system will be applied to glass and metals processing (by P MICREON). The peak power of the pulses generated by this second MOPA will be in the range of 40 MW at 1064nm. We expect more than 10 µJ per pulse in the visible and 4 µJ in UV. _x000D__x000D_Specifically, the MOPA will consist of an Ytterbium-doped, passively mode-locked fiber oscillator (MULTITEL), a fiber-based pre-amplifier combined with a pulse-picker unit (LZH) and a power amplification stage using Neodymium-doped Vanadate crystals in single-pass operation (NEOLASE). Thus, complex and expensive regenerative, multi-pass operation as well as chirped pulse amplification will be avoided. This will pave the way to robust, reliable and cost effective systems, for which a volume price lower than 100 k€ will be intended, more than one-third less compared to competitive laser systems._x000D__x000D_For a successful accomplishment of the objectives within the proposed project, highly motivated Ps with complementary skills will be jointly collaborating in a consortium. It consists of four R&D performing SMEs (NEOLASE for power amplification, LASERSPEC for mid-infrared generation, OPTEC and MICREON for laser material processing) and two research institutes (MULTITEL and LZH, specialized within the field of fiber laser technology and related components). Only the corresponding (efforts, contributions….) synergetic potential on an European level makes it possible to address such ambitious goals during a two-year term project.

Acronym FRUITFUL (Reference Number: 7701)
Duration 01/09/2013 - 31/05/2016
Project Topic Development of high energy CPA free femtosecond lasers and wavelength converters for various materials micromachining (metallic and glass materials with visible and UV femtosecond pulses and polymer materials with mid-IR sources).
Network Eurostars
Call Eurostars Cut-Off 9

Project partner

Number Name Role Country
6 Multitel asbl Partner Belgium
6 Micreon GmbH Partner Germany
6 neoLASE GmbH Coordinator Germany
6 LaserSpec Partner Belgium
6 OPTEC Laser Micromachining Systems Partner Belgium
6 Laser Zentrum hannover e.V. Partner Germany