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2002
Conference Paper
Titel
Diode laser modules of highest brilliance for materials processing
Abstract
Beam quality and output power of mostly 2-dimensional stacked diode laser systems are insufficient for the demands of materials processing. To increase the output power at almost constant beam-quality, superimposition of diode laser bars of different wavelengths as well as polarization-multiplexing of s- and p-polarized laser beams is possible. Different techniques for wavelength-multiplexing have been developed. The so-called multi-filter concept of spanned coated etalon with edge-filters has turned out best. The concept features a modular design, simple adjustment and easy add-on of more wavelengths. Concerning the polarization-multiplexing we take advantage of the almost linear polarized diode laser bars. Ordinary used beam splitter cubes with a cemented structure are less qualified for high radiance. Hence the beam combination is achieved with beam displacers made of a birefringent crystal (YVO4) which provide high transmittance and convenient adaptation. Finally an experimental set-up with 8 diode laser bars of 4 different wavelengths, i.e. 8-times beam superimposition, is realized. The set-up called multiplexer obtains a radiance of about 4 x 10(exp 6) W cm-2 sr-1 and outnumbers all other comparable high power diode laser systems.
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