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High brightness fiber-coupled single emitter arrays

: Heinemann, S.; Regaard, B.; Schmidt, T.; Lewis, B.


Zediker, M.S. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
High-Power Diode Laser Technology and Applications VII : 26-27 January 2009, San Jose, California, United States
Bellingham, WA: SPIE, 2009 (SPIE Proceedings Series 7198)
ISBN: 978-0-8194-7444-5
ISBN: 0-8194-7444-4
ISSN: 0277-786X
Paper 71980Q
Conference "High-Power Diode Laser Technology and Applications" <7, 2009, San Jose/Calif.>
Conference Paper
Fraunhofer ILT ()

Commercial high power fiber coupled diode lasers reach power levels of 200W from a 0.2mm fiber, NA=0.2. 2D fiber coupled single emitter (SE) arrays are described delivering 500W from a 0.2mm fiber. The beam quality of standard 90m single emitter (SE) is 6mm*mrad (slow axis) and 0.7mm*mrad (fast axis) including errors from fast axis lensing. 3 SEs (24) can be arranged in slow axis (fast axis) to fill the aperture for coupling into a 0.2mm fiber, NA=0.2. For high efficiency, beam shaping optics are avoided. A lens array for slow axis collimation and a focusing optic complete the fiber coupled module. 44 SEs' are arranged as a 2D array, polarization multiplexed and coupled into a 0.2mm fiber, NA=0.2. 62% optical to optical and 75% coupling efficiency are achieved, close to the modeled coupling efficiency of 80%. Alignment tolerances in the system do account for additional losses. Precise manufacturing processes are essential. The SEs on submounts are soldered in one reflow process to a common heatsink and FAC-lensing station automatically aligns the lens based on image processing ensuring minimum total lensing errors (focusing and pointing) of each SE to < 15% of total spot size. Tighter tolerances during SE mounting, improved fast axis collimation and a redesigned coupling optic will increase the coupling efficiency to 80% resulting in 410W linear polarized output from the 0.2mm fiber, NA=0.2. Polarization (800W) and dense wavelength multiplexing (1.4kW) open the door to kilowatt level.