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Proceedings Paper

Recent brightness improvements of 976 nm high power laser bars
Author(s): Alexander Bachmann; Christian Lauer; Michael Furitsch; Harald König; Martin Müller; Uwe Strauß
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Paper Abstract

Pump modules for fiber lasers and fiber-coupled direct diode laser systems require laser diodes with a high beam quality. While in fast axis direction diode lasers exhibit a nearly diffraction limited output beam, the maximum usable output power is usually limited by the slow axis divergence blooming at high power levels. Measures to improve the lateral beam quality are subject of extensive research. Among the many influencing factors are the chip temperature, thermal crosstalk between emitters, thermal lensing, lateral waveguiding and lateral mode structure.

We present results on the improvements of the lateral beam divergence and brightness of gain-guided mini-bars for emission at 976 nm. For efficient fiber coupling into a 200 μm fiber with NA 0.22, the upper limit of the lateral beam parameter product is 15.5 mm mrad. Within the last years, the power level at this beam quality has been improved from 44 W to 52 W for the chips in production, enabling more cost efficient pump modules and laser systems.

Our work towards further improvements of the beam quality focuses on advanced chip designs featuring reduced thermal lensing and mode shaping. Recent R&D results will be presented, showing a further improvement of the beam quality by 15%. Also, results of a chip design with an improved lateral emitter design for highest brightness levels will be shown, yielding in a record high brightness saturation of 4.8 W/mm mrad.

Paper Details

Date Published: 22 February 2017
PDF: 9 pages
Proc. SPIE 10086, High-Power Diode Laser Technology XV, 1008602 (22 February 2017); doi: 10.1117/12.2262985
Show Author Affiliations
Alexander Bachmann, OSRAM Opto Semiconductors GmbH (Germany)
Christian Lauer, OSRAM Opto Semiconductors GmbH (Germany)
Michael Furitsch, OSRAM Opto Semiconductors GmbH (Germany)
Harald König, OSRAM Opto Semiconductors GmbH (Germany)
Martin Müller, OSRAM Opto Semiconductors GmbH (Germany)
Uwe Strauß, OSRAM Opto Semiconductors GmbH (Germany)

Published in SPIE Proceedings Vol. 10086:
High-Power Diode Laser Technology XV
Mark S. Zediker, Editor(s)

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