Aachen, Germany--In the KORONA cooperation project, research scientists from the Fraunhofer Institute for Laser Technology ILT installed an ultrafast femtosecond laser based on an Yb:INNOSLAB amplifier with frequency doubling at the Max Planck Institute of Quantum Optics MPQ (Garching, Germany) that offers the highest average output power of 280 W at 515 nm with diffraction-limited beam quality.
Average output power of several hundred Watts with diffraction-limited beam quality have been demonstrated using Ytterbium-doped laser media at 1 μm wavelength in fiber, INNOSLAB and thin-disk geometry. The Fraunhofer ILT scientists hold the record with their Yb:INNOSLAB amplifier, generating an output power of 1.1 kW. But these beam sources must be reliable and easy to operate if they are to be used widely in science and industry. The Fraunhofer ILT green femtosecond laser has an almost diffraction-limited beam quality of M² < 1.4 using near-industrial construction and a friendly user interface.
The laser works by amplifying the radiation from a commercial femtosecond laser with 3 W output power in a Yb:INNOSLAB amplifier to 470 W at a pulse duration of 700 fs and then doubling its frequency in a non-linear crystal. As a result, the scientists at the MPQ have an average power at their disposal which is one magnitude higher than that generated by commercially available systems.
Ultrashort-pulse lasers have manifold applications in materials processing, offering higher-precision ablation than lasers with longer pulses. The femtosecond laser can process materials such as glass which are otherwise transparent for light with the laser wavelength. This ability is based on the process of multiphoton absorption which occurs at high peak intensities. Frequency conversion from the infrared to the green spectral range doubles the photon energy. As a result, fewer photons are needed for absorption, making it more effective. Another application of green laser radiation is the processing of copper and other materials that absorb radiation particularly well in this spectral range.
The aim of the KORONA cooperation project between the Max-Planck-Gesellschaft and the Fraunhofer-Gesellschaft is to produce coherent radiation with wavelengths in the extreme ultraviolet region below 100 nm. This wavelength range can be opened up by generating high harmonics of femtosecond radiation. Scaling up the average power creates the potential for new applications in this wavelength range.
The company EdgeWave GmbH, a spin-off from Fraunhofer ILT, has been marketing pulsed solid-state lasers based on the INNOSLAB platform for scientific and industrial use for about ten years. The company Amphos GmbH, another Fraunhofer ILT spin-off, develops and sells Yb:INNOSLAB lasers in the power range from 100 W to 1000 W.
The Yb:INNOSLAB amplifier will be presented at LASER World of Photonics in Munich from May 23 to 26, 2011, on the joint Fraunhofer booth (Hall C2, Booth 330).
SOURCE: Fraunhofer ILT; www.ilt.fraunhofer.de/eng/ilt/pdf/eng/press/PM_fs-Laser_for_MPQ.pdf
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