Reliable QCW diode laser arrays for operation with high duty cycles

Kissel, H.; Faßbender, Wilhelm; Lotz, J.; Alegria, Kim; Koenning, Tobias; Stapleton, Dean; Patterson, Steve; Biesenbach, Jens

doi:10.1117/12.2004399

Cited by 8 publications

(8 citation statements)

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“…For studies into improved bar performance, copper foil contact is typically used for lower cost and faster and more flexible assembly, with R p subtracted after testing to reveal the performance of the bar itself, at the risk of introducing errors if R p varies [10]. At DILAS, LDA packaged QCW bars are a standard product, with state of the art power and efficiency, based on commercial diode laser bars with L = 1.5...2.0 mm [4][5]8]. The bars are also hard soldered between CuW carriers, with electrical and thermal contact made via the rear edge.…”

Section: °C Performance Progress Of Laser Diode Assembliesmentioning

confidence: 99%

“…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%

“…Here, we focus on sources operating close to λ op = 940 nm where τ = 1...3 ms and f ~ 10 Hz are typically used, for D = 1...3%. Low duty cycles D ≤ 3% allow the bars to be assembled into low-cost passively-cooled monolithic stack format [4][5]8]. Such stacks are then combined via an optical system to deliver the necessary intensity profile, homogeneity and divergence parameter [8].…”

Section: Introductionmentioning

confidence: 99%

“…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%

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Progress in high-energy-class diode laser pump sources

Crump

Frevert

Bugge

et al. 2015

High-Power Diode Laser Technology and Applications XIII

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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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Section: °C Performance Progress Of Laser Diode Assembliesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Progress in high-energy-class diode laser pump sources

Crump

Frevert

Bugge

et al. 2015

High-Power Diode Laser Technology and Applications XIII

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“…Typically, they operate at maximum pulse width τ = 1 ms and maximum repetition rate f = 10 Hz, corresponding to a duty cycle dc = 1% (see for example Refs. [2,3]). However, repetition rates of several hundred Hz are required to boost average power from the DPSSL and to increase the shot frequency [4] .…”

Section: Introductionmentioning

confidence: 99%

High duty cycle, highly efficient fiber coupled 940-nm pump module for high-energy solid-state lasers

Platz

Eppich

Rieprich

et al. 2016

High Pow Laser Sci Eng

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Tailored diode laser single emitters with long (6 mm) resonators and wide (1.2 mm) emission apertures that operate with 940 nm emission wavelength were assembled in novel edge-cooled vertically stacked arrays, and used to construct a compact and highly efficient fiber coupled pump source for Yb:YAG pulsed high-energy class solid-state lasers. The novel configuration is shown to allow repetition rates of 200 Hz at 1 ms pulse duration, at an output power of 130 W per single emitter. The emission of two stacked arrays was then optically combined to realize pump modules that deliver 6 kW peak power (pulse energy 6 J) from a 1.9 mm core diameter fiber, with wall plug efficiency of 50%. This represents a significant improvement in terms of duty cycle and electro-optical efficiency over conventional sources. The pump module has been successfully tested at the Max Born Institute, Berlin during trials for pumping of disk lasers.

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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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Reliable QCW diode laser arrays for operation with high duty cycles

Cited by 8 publications

References 0 publications

Progress in high-energy-class diode laser pump sources

Progress in high-energy-class diode laser pump sources

High duty cycle, highly efficient fiber coupled 940-nm pump module for high-energy solid-state lasers

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

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