19 February 2018 High-resolution smile measurement and control of wavelength-locked QCW and CW laser diode bars
Author Affiliations +
Proceedings Volume 10514, High-Power Diode Laser Technology XVI; 105140Z (2018) https://doi.org/10.1117/12.2290799
Event: SPIE LASE, 2018, San Francisco, California, United States
Abstract
High-power linewidth-narrowed applications of laser diode arrays demand high beam quality in the fast, or vertical, axis. This requires very high fast-axis collimation (FAC) quality with sub-mrad angular errors, especially where laser diode bars are wavelength-locked by a volume Bragg grating (VBG) to achieve high pumping efficiency in solid-state and fiber lasers. The micron-scale height deviation of emitters in a bar against the FAC lens causes the so-called smile effect with variable beam pointing errors and wavelength locking degradation.

We report a bar smile imaging setup allowing FAC-free smile measurement in both QCW and CW modes. By Gaussian beam simulation, we establish optimum smile imaging conditions to obtain high resolution and accuracy with well-resolved emitter images.

We then investigate the changes in the smile shape and magnitude under thermal stresses such as variable duty cycles in QCW mode and, ultimately, CW operation. Our smile measurement setup provides useful insights into the smile behavior and correlation between the bar collimation in QCW mode and operating conditions under CW pumping. With relaxed alignment tolerances afforded by our measurement setup, we can screen bars for smile compliance and potential VBG lockability prior to assembly, with benefits in both lower manufacturing costs and higher yield.
Conference Presentation
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Etai Rosenkrantz, Dan Yanson, Genady Klumel, Moshe Blonder, Noam Rappaport, Ophir Peleg, "High-resolution smile measurement and control of wavelength-locked QCW and CW laser diode bars", Proc. SPIE 10514, High-Power Diode Laser Technology XVI, 105140Z (19 February 2018); doi: 10.1117/12.2290799; https://doi.org/10.1117/12.2290799
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