A new 100μm aperture, 920nm laser diode chip was developed to improve fiber coupling efficiency and reliability. These chips have been assembled into single-emitter and multi-emitter packages with 105μm diameter fiber-coupled output. The single-emitter package is rated for 12W operation, while the multi-emitter package is rated at 140W. Power conversion efficiency is 50%. Over one year of accelerated active life testing has been completed along with a suite of passive, environmental qualification tests. These pumps have been integrated into 2kW, 4kW, and 6kW fiber laser engines that demonstrate excellent brightness, efficiency, and sheet metal cutting quality and speed.
Hongbo Yu, Dahv A. Kliner, Kai-Hsiu Liao, Jeff Segall, Martin Muendel, James Morehead, Jane Shen, Matt Kutsuris, Johnny Luu, Justin Franke, Kelvin Nguyen, Dave Woods, Fred Vance, David Vecht, David Meng, Richard Duesterberg, Lei Xu, Jay Skidmore, Matthew Peters, Nicolas Guerin, James Guo, Jane Cheng, Jihua Du, Brad Johnson, Dongliang Yin, Allen Hsieh, Peter Cheng, Abdullah Demir, Jason Cai, Rupa Gurram, Kong-Weng Lee, Reddy Raju, Daniel Zou, Raman Srinivasan, Mandeep Saini, Laura Zavala, Victor Rossin, Erik Zucker, Hiroaki Ishiguro, Hiroshi Sako
We have demonstrated a monolithic (fully fused), 1.2-kW, Yb-doped fiber laser with near-single-mode beam quality.
This laser employs a new generation of high-brightness, fiber-coupled pump sources based on spatially multiplexed
single emitters, with each pump providing 100 W at 915 nm within 0.15 NA from a standard 105/125 μm fiber. The
fiber laser is end pumped through the high-reflector FBG using a 19:1 fused-fiber pump combiner, eliminating the need
for pump/signal combiners. The output wavelength is 1080 nm, with a linewidth of < 0.5 nm FWHM. A peak power of
1.5 kW was reached in modulated operation (1-ms pulse duration) with M2 < 1.2.
KEYWORDS: Thermoelectric materials, Performance modeling, Sensors, Finite element methods, Semiconductor lasers, 3D modeling, Semiconductors, Manufacturing, Data modeling, High power lasers
High-power single-emitter semiconductor lasers may dissipate up to several Watts heat load during operation. The heat
may be generated from a narrow stripe, as low as a few microns in width by several millimeters in length.
Thermoelectric Coolers (TEC) are widely deployed to control the laser junction temperature in single-emitter
semiconductor-laser packages. TEC manufacturers supply performance curves under the assumption of uniform heat
load applied to the cold plate. In reality, the heat will spread laterally across the cold plate creating a temperature
gradient across the couples. Consequently, the actual performance of the TEC may be significantly degraded as
compared to that predicted from the manufacturer's guidelines. A quantitative analysis that includes these deviations is
necessary to properly size the TEC and optimize the package design. This paper provides a simple method for modeling
the TEC performance parameters on concentrated heat loads using commercially-available FEA software. Experimental
data of TEC cooled single-emitter laser packages will also be presented that corroborate the results of our model.
We present performance improvements of fiber-coupled pump modules and broad-area lasers at 8xx nm, 9xx nm and 14xx nm wavelengths. Broad-area lasers with a 200 μm aperture at 808 nm for direct diode applications emit 11W CW and 30W pulsed. Pump modules at 830 nm for printing applications show excellent linearity, power stability of 2% and 95% of the power within 0.12 NA into a 50 μm core fiber at 1W CW. Broad-area lasers at 880 nm for pumping applications emit 18W CW with a peak wallplug efficiency of 64%. An improved design of 9xx pump modules is demonstrated with built-in feedback-protection (>30 dB at 1060 nm) that allows safe operation in multi-kW peak-power fiber lasers. Up to 3W of optical power with slope efficiency and peak wallplug efficiency of 0.64 W/A and 46%, respectively, is presented for 14xx nm broad-area lasers with a 100 μm wide aperture.
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