Diagnosing and addressing the limitations to lateral far field angle in high power broad-area diode lasers

Crump, P.; Böldicke, S; Schultz, C. M.; Ekhteraei, H.; Wenzel, H.; Erbert, G.

doi:10.1109/phosst.2012.6280787

Cited by 4 publications

(1 citation statement)

References 3 publications

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“…In order to reduce the underlying thermal lens effect in broad area laser diodes, humping pillars of plated gold [1] and copper pedestals under emitters [2,3] have been used as thermal path to minimize the thermal gradient across the slow axis direction. Control of slow axis mode behavior with phase structures in broad area lasers [4,5], mode filters [6] and current path structuring [7] have also been reported. Unfortunately, most of these publications report methods for beam quality improvements of semiconductor broad area diode lasers that sacrifice device efficiency and reliable output power.…”

Section: Introductionmentioning

confidence: 97%

Methods for slow axis beam quality improvement of high power broad area diode lasers

Xiong

Jiang

et al. 2014

SPIE Proceedings

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For high brightness direct diode laser systems, it is of fundamental importance to improve the slow axis beam quality of the incorporated laser diodes regardless what beam combining technology is applied. To further advance our products in terms of increased brightness at a high power level, we must optimize the slow axis beam quality despite the far field blooming at high current levels. The later is caused predominantly by the built-in index step in combination with the thermal lens effect. Most of the methods for beam quality improvements reported in publications sacrifice the device efficiency and reliable output power. In order to improve the beam quality as well as maintain the efficiency and reliable output power, we investigated methods of influencing local heat generation to reduce the thermal gradient across the slow axis direction, optimizing the built-in index step and discriminating high order modes. Based on our findings, we have combined different methods in our new device design. Subsequently, the beam parameter product (BPP) of a 10% fill factor bar has improved by approximately 30% at 7 W/emitter without efficiency penalty. This technology has enabled fiber coupled high brightness multi-kilowatt direct diode laser systems. In this paper, we will elaborate on the methods used as well as the results achieved.

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Section: Introductionmentioning

confidence: 97%

Methods for slow axis beam quality improvement of high power broad area diode lasers

Xiong

Jiang

et al. 2014

SPIE Proceedings

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Electro-optical efficiency and slow axis far-field improvement of high power laser diode bars using epitaxy structure optimization

Liu¹,

Holly²,

Jiang³

et al. 2017

2017 IEEE High Power Diode Lasers and Systems Conference (HPD)

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Methods for Slow Axis Beam Quality Improvements Leading to High Brightness Multi-kW Direct Diode Laser Systems

Xiong

Jiang

et al. 2014

2014 International Semiconductor Laser Conference

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We will present methods we used to further improve the slow axis BPP without efficiency penalty. Results of performance for multi-KW direct diode laser system application with this technology will be presented as well. IntroductionFor high brightness direct diode laser systems it is of fundamental importance to improve the slow axis beam quality of the incorporated laser diodes regardless what beam combining technology is applied. The beam quality is predominantly determined by the build in index step in combination with the thermal lens effect. According to device analysis and related simulations, with increasing operation current, the self-heating nature of the waveguide causes an increase in the thermal gradient between the waveguide and surrounding materials. Consequently, higher order modes reach their thresholds, yielding larger lateral far fields. In order to reduce the underlying thermal lens effect in broad area laser diodes, humping pillars of plated gold [1] and copper pedestals under emitters [2, 3] have been used as thermal path to minimize the thermal gradient across the slow axis direction. Control of slow axis mode behavior with phase structures in broad area lasers [4,5], mode filters [6] and current path structuring [7] have also been reported. Unfortunately, most of these publications report methods for beam quality improvements of semiconductor broad area diode lasers that sacrifice device efficiency and reliable output power. To improve beam quality as well as increase efficiency and reliable output power, we investigated methods of reducing local heat generation, thermal gradient across the slow axis direction and discriminating high order modes. We have already reported results of lateral waveguide design based on the control of lateral index difference and the discrimination of high order modes [8]. Based on our findings from experiments, we have combined these different methods in our new device design. Subsequently, the beam parameter product (BPP) of laser diode bars with 10% fill factor has improved by approximately 30% at the ~7W/emitter operation power without efficiency penalty. The same technology has also been applied on various fiber coupled high brightness multi-kilowatt direct diode laser products. In this paper, we will elaborate on methods we used as well as test results our new products yielded.

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Diagnosing and addressing the limitations to lateral far field angle in high power broad-area diode lasers

Cited by 4 publications

References 3 publications

Methods for slow axis beam quality improvement of high power broad area diode lasers

Methods for slow axis beam quality improvement of high power broad area diode lasers

Electro-optical efficiency and slow axis far-field improvement of high power laser diode bars using epitaxy structure optimization

Methods for Slow Axis Beam Quality Improvements Leading to High Brightness Multi-kW Direct Diode Laser Systems

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