Scaling brilliance of high power laser diodes

König, Harald; Grönninger, Guenther; Lauer, Christian; Reill, W.; Arzberger, M.; Strauß, Uwe; Kissel, H.; Biesenbach, Jens; Kösters, Arnd; Malchus, Joerg; Krause, Volker

doi:10.1117/12.841775

Cited by 11 publications

(3 citation statements)

References 3 publications

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“…Although vertically single moded, these devices operate in multiple lateral modes, limiting how effectively they can be laterally collimated and fibre coupled [3][4][5][6][7][8][9][10][11][12][13]. The techniques necessary to significantly reduce this far field angle (and to improve the beam quality) continue to be intensively studied [1,2,10,11,[14][15][16][17]. In the vertical axis, the guided optical modes are predominantly determined by the refractive index profile of the epitaxial layer structure, and the structure is limited by design to one vertical mode (although vertical mode profile changes have been observed at very high injection levels [18]).…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical analysis of the dominant lateral waveguiding mechanism in 975 nm high power broad area diode lasers

Crump

Böldicke

Schultz

et al. 2012

Semicond. Sci. Technol.

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For maximum fibre-coupled power, high power broad area diode lasers must operate with small lateral far field angles at high continuous wave (CW) powers. However, these structures are laterally multi-moded, with low beam quality and wide emission angles. In order to experimentally determine the origin of the low beam quality, spectrally resolved near and far field measurements were performed for a diode laser with 50 μm stripe width. Within the range measured (CW optical output powers to 1.5 W) the laser is shown to operate in just six stable lateral modes, with spatially periodic profiles. Comparisons of the measured profiles with the results of two-dimensional modal simulation demonstrate that current-induced thermal lensing dominates the lateral waveguiding, in spite of the presence of both strong built-in index guiding and gain guiding. No evidence is seen for filamentation. Building on the diagnosis, proposals are presented for improvements to beam quality.

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Section: Introductionmentioning

confidence: 99%

Experimental and theoretical analysis of the dominant lateral waveguiding mechanism in 975 nm high power broad area diode lasers

Crump

Böldicke

Schultz

et al. 2012

Semicond. Sci. Technol.

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“…The value of the SA-divergence has been reported to depend on many empirical parameters [13][14][15][16][17][18] , e.g. epitaxial design, emission aperture, die bonding and cavity length, which are relatively easy to control.…”

Section: Slow-axis Divergencementioning

confidence: 99%

Record CW-brightness from a single 20% fill-factor 1-cm laser-diode bar at 20°C

Chin¹,

Knapczyk

Jacob

et al. 2011

SPIE Proceedings

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A record, 250W, CW output-power has been achieved for a single, 1cm-wide, 3.5mm cavity-length, 20% fill-factor, 976nm, laser-diode bar operated at 20°C. The remarkable laser-bar performance was in part the result of a novel EPIC (Enhanced Performance Impingement Cooler) heat-sink with a thermal resistance of 0.16K/W. The superb thermal management resulted in record brightness for a laser bar, i.e. a slow-axis divergence of 10° (95% power containment angle) was achieved at 200W output-power. A coupling efficiency of ~74% into a 200μm core, 0.22NA fiber was achieved.

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“…Despite the low inherent spatial brightness of diode lasers, substantial progress has been made in recent years. Using coarse wavelength multiplexing, BPP in the range of 30 mm-mrad for kW-class diode lasers (corresponding to a 600 m core diameter output fiber with 0.1 NA) has been demonstrated [1][2][3]. However, significant improvement in BPP is still needed to address industrial applications requiring high brightness.…”

mentioning

confidence: 99%

Next generation of ultra high brightness direct diode lasers

Huang

Chann

Burgess

et al. 2013

2013 Conference on Lasers &Amp; Electro-Optics Europe &Amp; International Quantum Electronics Conference CLEO EUROPE/IQEC

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Direct diode lasers have some of the most attractive features of any laser. They are very efficient, compact, wavelength versatile, low cost, and highly reliable. However, the full utilization of direct diode lasers has yet to be realized. This is mainly due their poor output beam quality. Because of this, direct diode lasers are typically used to pump other lasers such as bulk solid-state (rod and thin disk) and fiber lasers. In other words these other lasers are primarily used as brightness converters. Thus, currently industrial lasers for high brightness applications such as cutting and welding are dominated by CO 2 , fiber, and bulk solid-state lasers.TeraDiode, using a revolutionary beam shaping technology, for the first time, has built direct diode lasers with output power and beam quality that are comparable to that of existing industrial lasers. The technology is scalable to tens of kW of output power while maintaining very high beam quality. Using our first kW-class direct diode laser we cut gaugethickness metal with comparable quality as existing industrial lasers.A large potential market exists for kilowatt-class direct-diode lasers with brightness sufficient for industrial processes including cutting and keyhole welding of sheet metal. Conventional direct-diode lasers offer competitive price and high reliability but lack sufficient brightness to carry out the most demanding materials processing or pumping applications. High-power and high-brightness fiber-coupled direct diode lasers offer superior efficiency, price, reliability and performance for both military and industrial applications.Diode lasers are the highest efficiency lasers, but their spatial brightness reported to date is relatively low compared to that of other kW-class lasers used in industrial applications. These kW-class lasers include CO 2 , fiber, bulk solid state lasers and disk lasers. For example, in cutting and welding sheet metal, beam parameter product (BPP) in the range of 3 to 10 mm-mrad is often needed. In the kW-class, fiber-coupled diode lasers typically have significantly higher BPP values. Despite the low inherent spatial brightness of diode lasers, substantial progress has been made in recent years. Using coarse wavelength multiplexing, BPP in the range of 30 mm-mrad for kW-class diode lasers (corresponding to a 600 m core diameter output fiber with 0.1 NA) has been demonstrated [1-3]. However, significant improvement in BPP is still needed to address industrial applications requiring high brightness.TeraDiode has developed an ultra-high brightness fiber-coupled diode laser using a novel beam combining and shaping technology. This fiber-coupled direct diode laser delivers more than 2kW at a single center wavelength from a 50 μm core diameter, 0.2 numerical aperture (NA) output fiber (1/e 2 power content). The BPP of 4 mm-mrad is substantially lower than that of other previously demonstrated fiber-coupled, direct diode lasers. Furthermore, the center wavelength of this laser is stabilized over the entire power range.

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Scaling brilliance of high power laser diodes

Cited by 11 publications

References 3 publications

Experimental and theoretical analysis of the dominant lateral waveguiding mechanism in 975 nm high power broad area diode lasers

Experimental and theoretical analysis of the dominant lateral waveguiding mechanism in 975 nm high power broad area diode lasers

Record CW-brightness from a single 20% fill-factor 1-cm laser-diode bar at 20°C

Next generation of ultra high brightness direct diode lasers

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