70% efficient near 1kW single 1-cm laser-diode bar at 20°C

Knapczyk, M.; Jacob, J. H.; Eppich, Henry; Chin, A. K.; Lang, K. D.; Vignati, J. T.; Chin, Richard

doi:10.1117/12.873179

Cited by 5 publications

(5 citation statements)

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“…The output power of single-emitter semiconductor lasers is greatly limited. Concentrating multiple emitters on a bar is a common way to achieve high power [5,6]. However, the near-field nonlinearity of the laser bar (also known as the smile effect) limits its wider application.…”

Section: Introductionmentioning

confidence: 99%

Method to reduce the smile of high-power diode laser bar by balancing the thermal-induced stress

Zhou

et al. 2022

Semiconductor Lasers and Applications XII

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The smile effect of the laser bar increases the difficulty of laser beam coupling and limits its application. In this paper, the smile effect in the high-power laser on the microchannel cooler (MCC) and the method of reducing the smile effect by balancing the thermal-induced stress are studied. The model of diode laser packaging with MCC is established based on the finite-element method (FEM). The effect of the thickness of the N-foil on the smile effect and stress is analyzed. The bar is bent into a convex shape after the bar is bonded to the heat sink, according to the simulation. With the increase of the thickness of the N-foil, the bar deformation gradually decreases, and then the middle part of the bar reversely increases. The thermal-induced stress on the bar is balanced by optimizing the thickness of the N-foil. The minimum deformation was less than 0.2 μm.

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Section: Introductionmentioning

confidence: 99%

Method to reduce the smile of high-power diode laser bar by balancing the thermal-induced stress

Zhou

et al. 2022

Semiconductor Lasers and Applications XII

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“…Reducing the thermal fraction of the rollover at high currents is crucial, especially when the laser is operated in elevated temperature regimes. This field is of special interest for the deployment of CW-driven, water-cooled kWclass diode laser bars, where high junction temperatures are easily reached [2][3][4][5]. Laser diodes with extreme double asymmetric structure (EDAS) epitaxial designs, also termed asymmetric decoupled confinement heterostructures (ADCHs) by other authors, and which have very thin p-waveguides, have been shown to operate with reduced optical losses and series resistance as well as reduced biasdriven carrier leakage (also termed as carrier accumulation in the waveguide by other authors) compared to symmetrical vertical designs [6], so are potentially well suited for such applications.…”

Section: Introductionmentioning

confidence: 99%

“…Here, s n and s p are the electron and hole absorption cross sections, respectively. The best values of both optical loss and series resistance are obtained by applying a doping level in the waveguide that varies between -10 cm 16 3 near the interface with the active layer and -• 5 10 cm 17 3 near the interface with the cladding layer. Biasdriven leakage currents are anticipated to be largely suppressed by the high p-side potential barrier.…”

Section: Introductionmentioning

confidence: 99%

Suppressed power saturation due to optimized optical confinement in 9xx nm high-power diode lasers that use extreme double asymmetric vertical designs

Kaul

Erbert

Maaßdorf

et al. 2018

Semicond. Sci. Technol.

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Broad area lasers with novel extreme double asymmetric structure (EDAS) vertical designs featuring increased optical confinement in the quantum well, Γ, are shown to have improved temperature stability without compromising series resistance, internal efficiency or losses. Specifically, we present here vertical design considerations for the improved continuous wave (CW) performance of devices operating at 940 nm, based on systematically increasing Γ from 0.26% to 1.1%, and discuss the impact on power saturation mechanisms. The results indicate that key power saturation mechanisms at high temperatures originate in high threshold carrier densities, which arise in the quantum well at low Γ. The characteristic temperatures, T 0 and T 1 , are determined under short pulse conditions and are used to clarify the thermal contribution to power limiting mechanisms. Although increased Γ reduces thermal power saturation, it is accompanied by increased optical absorption losses in the active region, which has a significant impact on the differential external quantum efficiency, h diff . To quantify the impact of internal optical losses contributed by the quantum well, a resonator length-dependent simulation of h diff is performed and compared to the experiment, which also allows the estimation of experimental values for the light absorption cross sections of electrons and holes inside the quantum well. Overall, the analysis enables vertical designs to be developed, for devices with maximized power conversion efficiency at high CW optical power and high temperatures, in a trade-off between absorption in the well and power saturation. The best balance to date is achieved in devices using EDAS designs with G = 0.54%, which deliver efficiencies of 50% at 14 W optical output power at an elevated junction temperature of 105 °C.

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“…Parallel studies into bipolar cascade lasers at λ = 88× nm have also delivered P out = 1.77 kW (τ = 0.2 ms f = 14 Hz T HS = 10°C) in a 3-stack configuration [4], for pumping Nd-doped crystals. Bars have also been demonstrated at λ = 940nm with continuous wave P out = 0.95 kW/bar and η E = 53%, with long resonators (5 mm), high fill factor (77%) and advanced cooling critical [5].…”

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confidence: 99%

“…The length of the CuW carriers is increased from 2 mm in [6] to be compatible with bars with L = 4 mm (insets to Figs. 4,5).…”

mentioning

confidence: 99%

Joule-Class 940-nm Diode Laser Bars for Millisecond Pulse Applications

Crump

Frevert

Ginolas

et al. 2015

IEEE Photon. Technol. Lett.

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The use of long resonators (for improved thermal and electrical resistance) and advanced facet passivation (for high power) is shown to enable Joule-class pulse emission from single passively cooled 1-cm diode laser bars emitting at 940 nm. Bars on CS-mount deliver pulse energy of 1 J at 60% power conversion efficiency within a 7-nm spectral window, under quasi-continuous wave conditions (1.2 ms 10 Hz). Robustness of device performance is confirmed via burn-in and multisite testing. Joule-per-bar performance is also maintained for conduction cooled monolithic stacked arrays, adapted for bars with long resonators. Although these packages only cool the laser bar via their rear edge, peak power, lateral far field, and spectral width remain consistent with the requirements for pumping solid state lasers and scale as predicted with self-heating. An energy density >10 J/cm 2 is delivered from the stack surface, for brightness >3 MW/(cm 2 -sr).

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70% efficient near 1kW single 1-cm laser-diode bar at 20°C

Cited by 5 publications

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Method to reduce the smile of high-power diode laser bar by balancing the thermal-induced stress

Method to reduce the smile of high-power diode laser bar by balancing the thermal-induced stress

Suppressed power saturation due to optimized optical confinement in 9xx nm high-power diode lasers that use extreme double asymmetric vertical designs

Joule-Class 940-nm Diode Laser Bars for Millisecond Pulse Applications

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