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Broad area laser in external resonator
What:
(Almost) fundamental mode operation of broad area diode lasers in external resonator.
Why:
- Higher power densities
- frequency conversion (SHG, upconversion)
- Coupling into single mode fibers
- pumping of microchip lasers
- welding of plastic components
- illumination, bleaching, heating et.al. with micrometer precision
How:
external resonators for influencing transversal modenstructure
Starting point:
Transversal multimode-operation ca. 60-fold worse than physical limit at 2W optical power.
Ansatz:
novel resonator concept:
- stable resonator along slow-axis
- optional modefiltering
- operation not along optical axis but under angle
Resonator
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Results
Improvement in brightness by factor 12
Variabel between 0.4W optical power with M2 = 1.03 and 1.1W optical power with M2 = 2.7
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The intensity distribution in the beam waist at an output power of 400mW is identical to a gaussian distribution
except for small deviations in the tails.
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The beam caustic as measured behind an f=75 mm lens at an output power of 400mW yields an M2 = 1,03.
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The intensity distribution in the beam waist at an output power of 1.1W shows small deviations from an ideal
gaussian distribution.
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The beam caustic as measured behind an f=75 mm lens at an output power of 1.1W yields an M2 = 2,7.
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Feasability study
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first short Video (2.9 MB)
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second short video (5.9 MB)
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Danilo Skoczowsky
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German
