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Proceedings Paper

Narrow-line fiber-coupled modules for DPAL pumping
Author(s): Tobias Koenning; Dan McCormick; David Irvin; Dean Stapleton; Tina Guiney; Steve Patterson
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Paper Abstract

Recent advances in high power diode laser technologies have enabled advanced research on diode pumped alkali metal vapor lasers (DPALs). Due to their low quantum defect, DPALs offer the promise of scalability to very high average power levels while maintaining excellent beam quality. Research is being conducted on a variety of gain media species, requiring different pump wavelengths: near 852nm for cesium, 780nm for rubidium, 766nm for potassium, and 670nm for lithium atoms. The biggest challenge in pumping these materials efficiently is the narrow gain media absorption band of approximately 0.01nm. Typical high power diode lasers achieve spectral widths around 3nm (FWHM) in the near infrared spectrum. Gratings may be used internal or external to the cavity to reduce the spectral width to 0.5nm to 1nm for high power diode laser modules. Recently, experimental results have shown narrower line widths ranging from picometers (pm) at very low power levels to sub-100 picometers for water cooled stacks around 1kW of output power. The focus of this work is a further reduction in the spectral line width of high power diode laser bars emitting at 766nm, with full applicability to other wavelengths of interest. One factor limiting the reduction of the spectral line width is the optical absorption induced thermal gradient inside the volume Bragg grating (VBG). Simulated profiles and demonstrated techniques to minimize thermal gradients will be presented. To enable the next stage of DPAL research, a new series of fiber coupled modules is being introduced featuring greater than 400W from a 600μm core fiber of 0.22NA. The modules achieve a spectral width of <<0.1nm and wavelength tunability of +/- 0.15nm.

Paper Details

Date Published: 13 March 2015
PDF: 9 pages
Proc. SPIE 9348, High-Power Diode Laser Technology and Applications XIII, 934805 (13 March 2015); doi: 10.1117/12.2082654
Show Author Affiliations
Tobias Koenning, DILAS Diode Laser, Inc. (United States)
Dan McCormick, DILAS Diode Laser, Inc. (United States)
David Irvin, DILAS Diode Laser, Inc. (United States)
Dean Stapleton, DILAS Diode Laser, Inc. (United States)
Tina Guiney, DILAS Diode Laser, Inc. (United States)
Steve Patterson, DILAS Diode Laser, Inc. (United States)

Published in SPIE Proceedings Vol. 9348:
High-Power Diode Laser Technology and Applications XIII
Mark S. Zediker, Editor(s)

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