Assessing the influence of the vertical epitaxial layer design on the lateral beam quality of high-power broad area diode lasers

Winterfeldt, M.; Rieprich, J.; Knigge, S.; Maaßdorf, A.; Hempel, Martin; Kernke, Robert; Tomm, Jens W.; Erbert, G.; Crump, P.

doi:10.1117/12.2210838

Cited by 10 publications

(4 citation statements)

References 18 publications

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“…For broad area high power laser diode, the lateral far-field increase as the operation current increase. the optical mode is not only affected the etched index guided waveguide, but also affected by several other phenomena, such as thermal lensing induced by self-heating, lateral carrier accumulation at the stripe edges, lateral spatial hole burning, filamentation, and so on [5][6][7][8][9] . the optical mode and gain / loss distribution along lateral direction is modulated, higher order mode power lasing or the power percentage of high order mode increase, and lead to the lateral farfield booming.…”

Section: Introductionmentioning

confidence: 99%

Lateral brightness improvement of high-power semiconductor laser diode

Tan

Liu

Wang

et al. 2023

High-Power Diode Laser Technology XXI

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High power diode lasers are widely used as the pump sources for fiber lasers and solid-state lasers, or the light sources for direct diode laser systems. The lateral brightness of diode lasers is the key parameter for the optical system with fiber coupling. The lateral brightness of a typical broad area diode laser is limited by the far-field booming rather than optical power at high operation current. In this paper, the far-field booming theory will be analyzed based on experimental observation of carrier density distribution and temperature profile along lateral direction. The temperature nonuniformity and the resulting thermal lens effect are supposed to be the dominate factor. We develop a novel high brightness laser diode structure with properly designed contact metal layer to modify the thermal conductivity profile. The thermal simulation indicate that the thermal lens effect is suppressed and the lateral far-field angle is reduced. Laser diodes with 230 μm emitter width and optimized structure are fabricated and the optical properties is investigated. The lateral far-field angle is reduced at current over 40A The optical power with same lateral brightness is increased up to 20%. This structure gives a promising high brightness solution for high power laser diode with power over 35 W. Chips with longer cavity length obtain higher power up to 51W.

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Section: Introductionmentioning

confidence: 99%

Lateral brightness improvement of high-power semiconductor laser diode

Tan

Liu

Wang

et al. 2023

High-Power Diode Laser Technology XXI

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“…According to the waveguide theory, light will be confined to the high refractive index region. As a result, a filamentary structure is formed in BALs, which causes the optical field to develop into multiple lobes in the near and far fields [36]. Figure 1 shows the far-field image of a BAL, where several filaments with different intensities can be seen in the picture.…”

Section: Filamentation In Balsmentioning

confidence: 99%

Spatial coherence research and passive speckle suppression for edge-emitting broad-area semiconductor lasers

Chen,

Zhang,

Zhou

et al. 2024

J. Opt.

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The spatial coherence of filaments in edge-emitting broad-area semiconductor lasers is researched based on speckle theory, and a passive speckle suppression method for broad-area semiconductor lasers is demonstrated. A Fly-eye lens is used to integrate the filaments and homogenize the laser beam. Speckle contrast is consistent with theoretical calculation, which proves the spatial incoherence of filaments. A light pipe is used to introduce optical path difference between light with different incident angles, enabling more incoherent beamlets. These beamlets are then combined at different illuminating angles by a double-sided fly-eye lens and focusing lens. As a result, the subjective speckle contrast is reduced from 95.94% to 19.13% at 1.2A, while maintaining a high luminous efficiency of 77.8%. This work provides important design principles for laser display systems.

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“…This behaviour is presented here for an exemplary EDAS diode design with G = 0.26% in figure 1(b), where the CW power-voltage-current (PUI) characteristics at 25 °C and 75 °C heatsink temperature are shown. This vertical structure is used here throughout as a baseline and is taken from [11].…”

Section: Chip Design and The Challenge For Improvementmentioning

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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Assessing the influence of the vertical epitaxial layer design on the lateral beam quality of high-power broad area diode lasers

Cited by 10 publications

References 18 publications

Lateral brightness improvement of high-power semiconductor laser diode

Lateral brightness improvement of high-power semiconductor laser diode

Spatial coherence research and passive speckle suppression for edge-emitting broad-area semiconductor lasers

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

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