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Increased coupling efficiency of fiber coupled modules by smile compensation
Author(s): Gabriel Pelegrina-Bonilla; Thomas Mitra
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Paper Abstract

A technique is experimentally demonstrated which allows for the compensation of the smile of a laser diode bar using a beam transformation system and a telescope array. The beam transformation system consists of a fast-axis collimator and an array of biconvex cylindrical lenses, which rotates each collimated beam by 90°. The telescope array is placed immediately behind and allows to address each emitter independently. The telescope array has two effects that reduce the fast-axis divergence: one is the magnification of the beams by effectively filling out the space between the beams, and the other the compensation of the smile-induced beam pointing by decentering the vertices of the concave entrance lens. In theory, this reduces the fast-axis divergence of a laser diode bar with 1 µm smile (peak-to-valley) from 7 mrad to 3.5 mrad, which would significantly increase the efficiency in fiber coupling applications. It is demonstrated in the experiment that it is possible to couple a full 19-emitter bar in a 100 μm core and 0.22 NA fiber with an overall fiber coupling efficiency of more than 75%. The telescope array is designed to be used with different, but similar smile forms. It is shown that slightly different smile forms have a negligible effect on the fiber coupling efficiency. Therefore, it is possible to compensate an arbitrary smile of a random laser diode bar by using a given set of optical modules.

Paper Details

Date Published: 4 March 2019
PDF: 7 pages
Proc. SPIE 10900, High-Power Diode Laser Technology XVII, 109000U (4 March 2019); doi: 10.1117/12.2509286
Show Author Affiliations
Gabriel Pelegrina-Bonilla, LIMO GmbH (Germany)
Thomas Mitra, LIMO GmbH (Germany)

Published in SPIE Proceedings Vol. 10900:
High-Power Diode Laser Technology XVII
Mark S. Zediker, Editor(s)

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