High duty-cycle, high-efficiency QCW stacks for medical applications

Kindsvater, Alex; Schröder, M.; Werner, Ekkehard; Seidel, S. C.; Wölz, Martin; Loyo-Maldonado, V.

doi:10.1117/12.2213630

Cited by 3 publications

(5 citation statements)

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“…. 3 × lower Z th than for the high duty-cycle optimized QCW bar design from [10] (e.g., saturation (cw) value for FBH: 0.038 K/W, [10]: 0.1 K/W, value at 1 ms: for FBH: 0.01 K/W, [10]: 0.025 K/W,) and longer saturation time (FBH: τ = 450 ms, [10]: τ = 112 ms). The time constant τ is obtained following [22], using the fit function given in Equation (1).…”

Section: Mode Of Operation Dutymentioning

confidence: 98%

“…Typically, Z th is a constant for a given τ p , f and packaging configuration, obtained using a linear fit to plots of T AR as a function of P therm . Figure 4 shows a comparison of Z th , measured in [10] for a rear-edge cooled commercial QCW stack and for the FBH design. In both cases, the values are calculated for HEC-DL sources (stacks) that are specifically designed for high duty cycle operation.…”

Section: Beam Quality Propertiesmentioning

confidence: 99%

“…Please note that higher τ leads to the module being less sensitive to rapid temperature changes, and hence more suitable for long-pulse operation. In addition the 1-cm bars in [10] are limited by the high duty cycle and high Z th values to operate with ca. P opt = 105 W per bar thus P opt = 105 W per 1 cm lateral aperture.…”

Section: Mode Of Operation Dutymentioning

confidence: 99%

“…P opt = 120 W from a 1200 µm lateral aperture, which is ca. 10 times higher brightness than in [10]. The high repetition rate pump sources presented here (and those from earlier generations), were used as part of the development of diode pumped solid state laser systems at the Max Born Institute (MBI), that use thin-disk Yb:YAG lasers to deliver pulses with f = 100 .…”

Section: Mode Of Operation Dutymentioning

confidence: 99%

“…Commercially available pump sources that can potentially deliver these parameters consist of stacks or arrays of high-energy class diode lasers (HEC-DL) in 1-cm bar format, with each bar combined with a fast axis collimation (FAC) lens. The bars are collected into pump modules, including customised optics for beam shaping and homogenizing [7][8][9][10][11][12]. There are two main configurations.…”

Section: Introductionmentioning

confidence: 99%

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Novel High-Power, High Repetition Rate Laser Diode Pump Modules Suitable for High-Energy Class Laser Facilities

et al. 2019

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The latest generation of high-energy-class pulsed laser facilities, under construction or planned, such as EuPRAXIA, require reliable pump sources with high power (many kW), brightness (>1 MW/cm2/sr) and electro-optical conversion efficiency (>50%). These new facilities will be operated at high repetition rates (around 100 Hz) and only diode lasers are capable of delivering the necessary performance. Commercial (quasi-continuous wave, QCW) diode laser pulse-pump sources are, however, constructed as low-cost passively cooled stacked arrays that are limited either in brightness, efficiency or repetition rate. Commercial continuous wave diode laser pumps constructed using microchannel coolers (as used in high-value industrial machine tools) can fulfil all requirements, but are typically not preferred, due to their cost and complexity and the challenges of preventing cooler degradation. A custom solution is shown here to fill this gap, using advanced diode lasers in a novel passive side-cooling geometry to realize 100 … 200 Hz pump modules (10%–20% duty cycle) that emit peak power of 6 kW at wavelength = 940 nm. The latest performance of these modules is summarized and compared to literature. We show that a brightness >1 MW/cm2/sr can be efficiently delivered across a wide range of laser pulse conditions with 10% duty cycle (pulse width: 100 µs … 100 ms … cw, repetition rate up to 1 kHz). Furthermore, we describe how these pumps have been used to construct and reliably operate (>109 pulses without degradation) in high-energy-class regenerative and ring amplifiers at the Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI). We also show first results on 100 Hz pumping of cryogenically cooled solid-state Yb:YAG slab amplifiers, as anticipated for use in the EuPRAXIA laser, and note that peak temperature is disproportionately increased, indicating that improved cooling and more detailed studies are needed.

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