New highly efficient laser bars and laser arrays for 8xx-10xx nm pumping applications

Pietrzak, A.; Huelsewede, Ralf; Zorn, M.; Hirsekorn, O.; Sebastian, J.; Meusel, J.; Bluemel, Veit; Hennig, Petra

doi:10.1117/12.2036917

Cited by 7 publications

(5 citation statements)

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“…Such low optical losses enable a realization of efficient lasers diode with 4 mm long cavities. Due to the very low α i the differential quantum efficiency for 1 mm long lasers (η diff,1mm = 88%) is only 3% lower than the internal efficiency and its high value is maintained also for lasers with 4 mm long resonators (η diff,4mm = 85%) [3] The new generation laser structures emitting at 976 nm have been processed in to 10 mm-laser bars composed of 19 emitters with 2 mm long cavities. Every emitter has a width of 100µm.…”

Section: Epitaxial Design For Highest Wall-plug Efficiencymentioning

confidence: 98%

“…The mini bar with 90 μm emitter have a brightness of 75 MWcm -2 sr -1 and a beam-parameter-product of BPP 95 = 3.9 mm°mrad (95% power content of 11 W/emitter). The measured near field profiles of the discussed mini bars are presented in [3] 3.3. 940nm / 1020 nm bars for CW applications 940 nm laser diodes are pump sources for disc lasers, but this wavelength is also suitable for direct material applications.…”

Section: XX Nm Mini Barsmentioning

confidence: 99%

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Research on 9xx nm diode laser for direct and pumping applications

Sebastian¹,

Hülsewede²,

Pietrzak³

et al. 2015

SPIE Proceedings

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High-power laser bars and single emitters have proven as attractive light sources for many industrial applications such as direct material processing or as pump sources for solid state and fiber-lasers. There is also a great interest in quasi-CW laser bars for high-energy projects. These applications require a continuous improvement of laser diodes for reliable optical output powers, high electrical-to-optical efficiencies, brightness and costs. In this paper JENOPTIK presents an overview of recent research for highly efficient CW and quasi-CW laser devices emitting in a wide wavelength range between 880 nm and 1020 nm. The last research results concern the 9xx single emitters and laser arrays. The 9xx nm 12 W single emitters and 976 nm 55 W laser arrays have efficiencies above 65%. New life time tests for single emitter devices currently exceed 1300 hours of reliable operation at room temperature and over 1500 hours at 45°C. Because of the small far field distribution of the optical power, the high output power and the small near field the 55 W arrays show a brightness of 75 MW x cm -2 sr -1 with 95% power content. The technology for new generation 940 nm high fill-factor bars has been currently extended to emission wavelengths of 976 nm and 1020 nm with excellent results: 200 W output power with 63% efficiency using passive cooling. The innovative design of the laser structure enables, moreover, the realization of 500 W 880 nm quasi-CW laser bars with wall-plug efficiencies of 55% and a narrow fast-axis divergence angle of 40° (95% power content).

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Section: Epitaxial Design For Highest Wall-plug Efficiencymentioning

confidence: 98%

Section: XX Nm Mini Barsmentioning

confidence: 99%

Research on 9xx nm diode laser for direct and pumping applications

Sebastian¹,

Hülsewede²,

Pietrzak³

et al. 2015

SPIE Proceedings

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“…Commercial bars operating close to λ op = 940 nm deliver an optical output power at the operating point of P op = 300...400 W per bar, with conversion efficiency η E = P op /(I op U op ) > 60% at drive current I op and bias voltage U op respectively [4][5][6]8]. Higher values of P op are required for reduced overall system cost in $/W and to enable improved amplifier performance.…”

Section: Introductionmentioning

confidence: 97%

“…The commercial diode lasers used to pump these systems are typically constructed in 1 cm bar format, and emit at an operating wavelength of λ op = 940 nm, 960...980nm, or 870...880 nm, as needed to pump Ytterbium-and Neodymium-doped solid-state media, respectively (see [4][5][6][7] and references therein). The bars are operated in quasi-continuous-wave (QCW) mode, with flattop pulses of width τ and repetition rate f tailored for the media in use, for duty cycle D = τ×f.…”

Section: Introductionmentioning

confidence: 99%

Progress in high-energy-class diode laser pump sources

et al. 2015

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A new generation of diode-pumped high-energy-class solid-state laser facilities is in development that generate multijoule pulse energies at around 10 Hz. Currently deployed quasi-continuous-wave (QCW) diode lasers deliver average inpulse pump powers of around 300 W per bar. Increased power-per-bar helps to reduce the system size, complexity and cost per Joule and the increased pump brilliance also enables more efficient operation of the solid state laser itself. It has been shown in recent studies, that optimized QCW diode laser bars centered at 940…980 nm can operate with an average in-pulse power of > 1000 W per bar, triple that of commercial sources. When operated at pulsed condition of 1 ms, 10 Hz, this corresponds to > 1 J/bar. We review here the status of these high-energy-class pump sources, showing how the highest powers are enabled by using long resonators (4…6 mm) for improved cooling and robustly passivated output facets for high reliability. Results are presented for prototype passively-cooled single bar assemblies and monolithic stacked QCW arrays. We confirm that 1 J/bar is sustained for fast-axis collimated stacks with a bar pitch of 1.7 mm, with narrow lateral far field angle (< 12° with 95% power) and spectral width (< 12 nm with 95% power). Such stacks are anticipated to enable Joule/bar pump densities to be used near-term in commercial high power diode laser systems. Finally, we briefly summarize the latest status of research into bars with higher efficiencies, including studies into operation at sub-zero temperatures (-70°C), which also enables higher powers and narrower far field and spectra.

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“…The Structure A is designed for shorter emission wavelengths (880 nm), short bars and high current densities [4]. The Structure B, tailored for emission wavelength ~940 nm, is a laser design which is optimized for long cavity lasers [4], but because it utilizes low resistivity materials, it works also well as short bars up to 500 W. The Structure C represent an improved epitaxial design against carrier leakage at even higher currents (>1 kA), with very low resistivity and is designed for long cavity bars.…”

Section: Introductionmentioning

confidence: 99%

Heading to 1 kW levels with laser bars of high-efficiency and emission wavelength around 880 nm and 940 nm

Pietrzak¹,

Woelz²,

Huelsewede³

et al. 2015

SPIE Proceedings

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High-power quasi-CW laser bars are of great interest as pump sources of solid-state lasers generating high-energy ultrashort pulses for high energy projects. These applications require a continuous improvement of the laser diodes for reliable optical output powers and simultaneously high electrical-to-optical power efficiencies. An overview is presented of recent progress at JENOPTIK in the development of commercial quasi-CW laser bars emitting around 880 nm and 940 nm optimized for peak performance. At first, performances of 1.5 mm long laser bars with 75% fill-factor are presented. Both, 880 nm and 940 nm laser bars deliver reliable power of 500 W with wall-plug-efficiencies (WPE) >55% within narrow beam divergence angles of 11° and 45° in slow-axis and fast-axis directions, respectively. The reliability tests at 500 W powers under application quasi-CW conditions are ongoing. Moreover, laser bars emitting at 880 nm tested under 100 µs current pulse duration deliver 1 kW output power at 0.9 kA with only a small degradation of the slope efficiency. The applications of 940 nm laser bars require longer optical pulses and higher repetition rates (1-2 ms, ~10 Hz). In order to achieve output powers at the level of 1 kW under such long pulse duration, heating of the laser active region has to be minimized. Power-voltage-current characteristics of 4 mm long cavity bars with 50% fill-factor based on an optimized laser structure for strong carrier confinement and low resistivity were measured. We report an output power of 0.8 kW at 0.8 A with >60% conversion efficiency (52% WPE). By increasing the fill-factor of the bars a further improvement of the WPE at high currents is expected.

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New highly efficient laser bars and laser arrays for 8xx-10xx nm pumping applications

Cited by 7 publications

References 0 publications

Research on 9xx nm diode laser for direct and pumping applications

Research on 9xx nm diode laser for direct and pumping applications

Progress in high-energy-class diode laser pump sources

Heading to 1 kW levels with laser bars of high-efficiency and emission wavelength around 880 nm and 940 nm

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