Femtosecond lasers (fs-lasers) are predominantly used in ultra-precision processing applications. Despite their utility in electronics, medicine, solar technology, aerospace and many others, the wider adoption of femtosecond lasers is constrained. This is due to the huge cost associated with their complex optical modules and their average power output, which is typically less than 100 W.
Now, a team of researchers at the German Fraunhofer Institute for Laser Technology (ILT) has been instrumental in developing a femtosecond laser system based on InnoSlab technology, capable of delivering more than 400 W.
Almost 35 years in existence, fs-lasers can generate pulse durations of less than one picosecond. Hence, the interaction of fs-lasers with a material results in the pulse duration being shorter than the interaction time between atoms. This means that all possible reactions, such as melting, evaporation, heat conduction and plasma formation begin to occur only after the impact of laser radiation.
Overall, fs-lasers have been long proven to be best suited for achieving superior results during ultra-precision processing. Despite the aforementioned benefits, fs-lasers until now were only capable of producing a less pronounced average power output. It should be noted that the average power output of fs-lasers is typically in the order of a single watt, whereas disk lasers and continuous wave (cw) lasers are capable of demonstrating an average power output in the kilowatt range.
With an attempt to improve the average power output of fs-lasers and also to limit costs, researchers at the Fraunhofer ILT have developed a powerful ultrashort-pulse laser in the order of 400 W. As it is based on InnoSlab technology, which has been the foundation for building a number of nano- and pico-second laser systems, the technology is based on a simple construction comprising a single-pass amplifier in combination with four mirrors and a laser crystal, which helps in the building of a thermally robust, opto-mechanical system.
Overall, the design permits generation of pulse energies below one millijoule, which is most appropriate for micromaterial processing. In addition, it is believed that the InnoSlab technology obviates the need to incorporate complex chirped pulse amplification (CPA) during material processing. This helps to reduce the overall cost incurred during the building of fs-laser based systems.
The fs-laser developed at Fraunhofer ILT is has been able to demonstrate pulse durations below 700 fs, spectral wavelengths below 2 nm, and distinctly shorter pulses, which are best suited for micromaterial processing applications. Apart from this, the beam can be said to be almost free of diffractions, which allows for the transformation of the incident beam into a rounded beam while further improving the application prospects of fs-lasers.
Also, as the system does not require additional attachments such as compressors, the need to perform time compression and the associated problems such as pulse front or phase front tilt are obviated in the system. The high pulse peak output power and the limited bandwidth spectrum of fs-lasers also makes them a suitable choice to perform nonlinear frequency conversion in ultra-precision processing applications.
For more information contact Patrick Cairns, Frost & Sullivan, +27 (0)21 680 3274, [email protected], www.frost.com
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version