Experimental Studies Into the Beam Parameter Product of GaAs High-Power Diode Lasers

Crump, P.; Elattar, Mohamed; Miah, Md. Jarez; Ekterai, M.; Karow, M. M.; Martin, D.; Maasdorf, A.; McDougall, S.D.; Holly, Carlo; Rauch, Simon; Gruetzner, Stefan; Strohmaier, Stephan; Tränkle, G.

doi:10.1109/jstqe.2021.3095660

Cited by 18 publications

(15 citation statements)

References 30 publications

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“…The change of the BPP lat with increasing ΔT is nearly identical, being slightly faster for the case of the ASLOC laser (S th = 0.36 vs. 0.33 mm.mrad/K). The reason for the lower BPP 0 for the ETAS laser requires further study: see [31]- [33]. Overall, the improvement in the BPP lat of the ETAS DBR lasers confirms the pattern observed in the FP BA lasers without DBRs in [21].…”

Section: Resultssupporting

confidence: 73%

“…The measured data points are fitted with a linear empirical fit BPP lat = BPP 0 + S th ΔT, following [30], where ΔT is the increase of the average temperature in the active region over T HS (calculated by multiplying the dissipated power within the device by the thermal resistance). BPP 0 represents the non-thermal background of the BPP lat which include contributions from all the effects nearly unaffected with temperature change, e.g., process or packaging related waveguiding [31]. The second term in the fit equation describes the change of the BPP lat due to internal heating, with S th representing the rate.…”

Section: Resultsmentioning

confidence: 99%

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60% Efficient Monolithically Wavelength-Stabilized 970-nm DBR Broad-Area Lasers

et al. 2022

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Progress in epitaxial design is shown to enable increased optical output power P opt and power conversion efficiency η E and decreased lateral far-field divergence angle in GaAs-based distributed Bragg reflector (DBR) broad-area (BA) diode lasers. We show that the wavelength-locked power can be significantly increased (saturation at high bias current is mitigated) by migrating from an asymmetric large optical cavity (ASLOC) based laser structure to a highly asymmetric (extreme-triple-asymmetric (ETAS)) layer design. For wavelength-stabilization, 7 th order, monolithic DBRs are etched on the surface of fully grown epitaxial layer structures. The investigated ETAS reference Fabry-Pérot (FP) BA lasers without DBRs and with 200 µm stripe width and 4 mm cavity length provide P opt = 29 W (still increasing) at 30 A in continuous-wave mode at room temperature, in contrast to the maximum P opt = 24 W (limited by strong power saturation) of baseline ASLOC lasers. The reference ETAS FP lasers also deliver over 10% higher η E at P opt = 24 W. On the other hand, in comparison to the wavelength-stabilized ASLOC DBR lasers, ETAS DBR lasers show a peak power increment from 14 W to 22 W, and an efficiency increment from 46% to 60% at P opt = 14 W. A narrow spectral width (< 1 nm at 95% power content) is maintained across a very wide operating range. Consistent with earlier studies, a narrower far-field divergence angle and consequently an improved beam-parameter product is also observed, compared to the ASLOC-based lasers.

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Section: Resultssupporting

confidence: 73%

Section: Resultsmentioning

confidence: 99%

60% Efficient Monolithically Wavelength-Stabilized 970-nm DBR Broad-Area Lasers

et al. 2022

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“…As can be seen in Fig. 9(b)(top), the TM-polarized emission is enhanced at the stripe edges of the IG emitters which is associated with the mechanical stress fields originating from the trenches there [18]. The absence of such mechanical stresses in gain-guided ETAS bars improves their DOP by 1-3% up to I opt = 1.8 kA.…”

Section: Improvement Of Beam Quality By Lateral Waveguidingmentioning

confidence: 85%

Optimizing Vertical and Lateral Waveguides of kW-Class Laser Bars for Higher Peak Power, Efficiency and Lateral Beam Quality

et al. 2022

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GaAs-based, highly-efficient, kW-class, 1-cm laser bars with high peak power P opt and improved beam quality in quasi-continuous-wave mode are presented. The use of an extreme-triple-asymmetric (ETAS) epitaxial layer structure diminishes power saturation of high-power bars at high driving current. The resulting ETAS bars with 4 mm cavity produce a record 1.9 kW peak power, limited by available current supply, with a maximum power conversion efficiency η E = 67% at T HS = 25 °C heat-sink temperature. Both P opt and η E have been increased further by operating the bars at T HS = −70 °C. Sub-zero operation raises the P opt to 2.3 kW and the maximum η E to 74%. A second configuration of ETAS bars with optimized lateral layout is further realized to obtain narrow lateral beam divergence θ up to 2 kA driving current, without sacrificing P opt and η E . A 2-3°lower θ (95% power level) is observed over a wide operating range at room temperature. A high degree of polarization is also maintained across the whole operating range.

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“…Such kW-class bars contain an array of broad-area (BA) emitters arranged side-byside in lateral direction. Experimental studies show that a strong thermal lens evolves during laser operation and the lensing effect becomes stronger with increasing operating power [8,9]. The resulting stronger waveguiding allows more transverse modes to contribute to the laser emission deteriorating the beam quality (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…A decrease in the thermal lensing in the emitters, by making the thermal profiles flatter, is an effective technique to improve the beam quality. For example, in [9], it has been shown that by bringing the emitters closer together in the bar the thermal interaction between the emitters can be enhanced which flattens the thermal profiles of the individual emitter and provides an overall lower θlat of the bar. Several other approaches have also been attempted, as recently reviewed in [9,10].…”

Section: Introductionmentioning

confidence: 99%

Tailored in-plane thermal profiles for narrower lateral far-field in kilowatt-class 9xx nm diode laser bars

Miah,

Karow,

Elattar

et al. 2023

High-Power Diode Laser Technology XXI

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Experimental Studies Into the Beam Parameter Product of GaAs High-Power Diode Lasers

Cited by 18 publications

References 30 publications

60% Efficient Monolithically Wavelength-Stabilized 970-nm DBR Broad-Area Lasers

60% Efficient Monolithically Wavelength-Stabilized 970-nm DBR Broad-Area Lasers

Optimizing Vertical and Lateral Waveguides of kW-Class Laser Bars for Higher Peak Power, Efficiency and Lateral Beam Quality

Tailored in-plane thermal profiles for narrower lateral far-field in kilowatt-class 9xx nm diode laser bars

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