High power T-Bars with narrow in-plane far-field angle

Lauer, Christian; Bachmann, Alexander; Grönninger, Günther; Kreuter, P.; Furitsch, M.; Grossmann, V.; Leisner, Malte; Sporrer, K.; Kissel, H.; Stoiber, Michael; Biesenbach, Jens; König, Harald; Strauβ, U.

doi:10.1109/islc.2014.137

Cited by 4 publications

(4 citation statements)

References 6 publications

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“…However, the conversion efficiency is reduced for higher currents, peaking at 55%. The linear brightness P opt /BPP lat = 3.5 W/mm×mrad is the highest achieved to date from a device with 90 μm contact width, comparable to best reported data on commercial devices [7], in spite of the reduction in efficiency, increased self-heating and resulting enhanced thermal lensing. The reduction in BPP lat is due to both reduced near field width and far field angle.…”

Section: Influence Of Carrier Profile On Performancesupporting

confidence: 76%

High Beam Quality in Broad Area Lasers via Suppression of Lateral Carrier Accumulation

Winterfeldt

Crump

Knigge

et al. 2015

IEEE Photon. Technol. Lett.

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High power 9xx-nm broad-area lasers with improved beam quality are required for many applications, but the physical limitations remain unclear, especially the relative importance of free-carrier and self-heating effects. Experimental data are, therefore, presented on a series of diagnostic lasers where the lateral carrier profile at the edges of the electrical contacts has been modified via implantation in order to assess its influence on beam quality. We show that carrier accumulation at the edges of the (90-µm wide) contacts can be eliminated and that as a consequence, near and far field are narrowed and the rate of increase of beam parameter product (BPP) with self-heating reduces by 35%. Overall, the suppression of lateral carrier accumulation allows BPP < 2 mm × mrad to be maintained to 7-W optical output, corresponding to a peak linear brightness of 3.5 W/mm × mrad, comparable with the highest reported values for 90-µm stripe devices.Index Terms-Broad area laser, deep implantation, lateral carrier profile, proton bombardment, slow axis beam quality.

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Section: Influence Of Carrier Profile On Performancesupporting

confidence: 76%

High Beam Quality in Broad Area Lasers via Suppression of Lateral Carrier Accumulation

Winterfeldt

Crump

Knigge

et al. 2015

IEEE Photon. Technol. Lett.

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“…In [2], the thermal resistance is R th ~ 4 K/W for diode lasers with L = 4 mm and W = 100µm, so for P op = 10 W and η E = 64%, the total self-heating of the active region is ΔT therm = R th × P op × (η E -1 -1) = 23 K, corresponding to a wavelength variation in operation of Δλ therm ~ 15 nm (from zero bias up to P op ). Therefore, a conventional device without spectral stabilization covers a total wavelength span of around 20 nm, which, accounting for manufacturing tolerances and the properties of optical filters, leads to a typical channel-to-channel wavelength spacing of ~ 35 nm [2], allowing the use of 5 channels across the highest performance wavelength range addressable by GaAs-based lasers (~900...1045 nm). If the diode lasers are wavelength-stabilized then both Δλ 95% and Δλ therm are reduced, and the number of available channels and hence maximum achievable power increases.…”

Section: Spectral Beam Combination Concept Within Bridlementioning

confidence: 99%

“…The optical energy for the majority of commercial systems is provided by high power GaAs-based diode lasers, which either deliver their light directly to the work surface or are used as a pump source for fiber or solid state lasers. State of the art commercial broadarea diode lasers (BAs) emitting in the λ = 940...980 nm wavelength range with stripe width W = 100 µm and resonator length L = 4 mm deliver continuous wave optical output power P op = 10 W at a conversion efficiency η E = 64% and a slow-axis divergence of Θ L 95% = 7° (at 95% power content) [2]. This corresponds to a lateral (slow-axis) linear brightness, B lin = P op / BPP = 3.3 W/mm×mrad [2], where BPP = 3 mm×mrad is given by BPP = 0.25 × Θ L 95% × W 95% and W 95% is the emission aperture at 95% power content.…”

Section: Introductionmentioning

confidence: 99%

“…State of the art commercial broadarea diode lasers (BAs) emitting in the λ = 940...980 nm wavelength range with stripe width W = 100 µm and resonator length L = 4 mm deliver continuous wave optical output power P op = 10 W at a conversion efficiency η E = 64% and a slow-axis divergence of Θ L 95% = 7° (at 95% power content) [2]. This corresponds to a lateral (slow-axis) linear brightness, B lin = P op / BPP = 3.3 W/mm×mrad [2], where BPP = 3 mm×mrad is given by BPP = 0.25 × Θ L 95% × W 95% and W 95% is the emission aperture at 95% power content. The brightness of these devices is comparable to laterally single mode lasers, which operate at P op ~ 1 W and diffraction limited BPP ~ 0.3 mm×mrad [3].…”

Section: Introductionmentioning

confidence: 99%

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Development of high-power diode lasers with beam parameter product below 2 mm×mrad within the BRIDLE project

Crump

Decker

Winterfeldt

et al. 2015

High-Power Diode Laser Technology and Applications XIII

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High power broad-area diode lasers are the most efficient source of optical energy, but cannot directly address many applications due to their high lateral beam parameter product BPP = 0.25 × Θ L 95% × W 95% (Θ L 95% and W 95% are emission angle and aperture at 95% power content), with BPP > 3 mm×mrad for W 95%~9 0µm. We review here progress within the BRIDLE project, that is developing diode lasers with BPP < 2 mm×mrad for use in direct metal cutting systems, where the highest efficiencies and powers are required. Two device concepts are compared: narrow-stripe broad-area (NBA) and tapered lasers (TPL), both with monolithically integrated gratings. NBAs use W 95% ~ 30 µm to cut-off higher order lateral modes and reduce BPP. TPLs monolithically combine a single mode region at the rear facet with a tapered amplifier, restricting the device to one lateral mode for lowest BPP. TPLs fabricated using ELoD (Extremely Low Divergence) epitaxial designs are shown to operate with BPP below 2mm×mrad, but at cost of low efficiency (<35%, due to high threshold current). In contrast, NBAs operate with BPP < 2 mm×mrad, but maintain efficiency >50% to output of > 7 W, so are currently the preferred design. In studies to further reduce BPP, lateral resonant anti-guiding structures have also been assessed. Optimized anti-guiding designs are shown to reduce BPP by 1 mm×mrad in conventional 90 µm stripe BA-lasers, without power penalty. In contrast, no BPP improvement is observed in NBA lasers, even though their spectrum indicates they are restricted to single mode operation. Mode filtering alone is therefore not sufficient, and further measures will be needed for reduced BPP.

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Study of lateral brightness in 20 μm to 50 μm wide narrow stripe broad area lasers

Decker

Winterfeldt

Fricke

et al. 2015

2015 IEEE High Power Diode Lasers and Systems Conference (HPD)

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High power T-Bars with narrow in-plane far-field angle

Cited by 4 publications

References 6 publications

High Beam Quality in Broad Area Lasers via Suppression of Lateral Carrier Accumulation

High Beam Quality in Broad Area Lasers via Suppression of Lateral Carrier Accumulation

Development of high-power diode lasers with beam parameter product below 2 mm×mrad within the BRIDLE project

Study of lateral brightness in 20 μm to 50 μm wide narrow stripe broad area lasers

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