Diode Lasers

Fiber-coupled diode lasers are among the least expensive and most efficient beam sources for cw laser applications; they are widely used, for example, in the hardening, soldering and welding of metals. Fraunhofer ILT develops diode lasers for tailor-made optical systems that meet high requirements. With its own self-developed as well as commercial software tools, the institute models and optimizes complex laser systems. Direct diode lasers with kW optical output power are a cost-effective alternative to fiber lasers in cutting applications. The stabilized emission spectrum and beam quality of the diode laser can also be used to great advantage in pump applications for multi-kW fiber lasers or ultra-short pulse lasers. In addition to targeted beam shaping, the institute also focuses its R&D activities on developing fiber coupling and wavelength stabilization of diode lasers.

The range of services it offers includes R&D in the field of design and simulation, experimental investigations of laboratory samples, the development of industry-oriented, certified prototypes and comprehensive technology consulting as well as market and feasibility studies.

Characterization of High Power Diode Lasers

• Near and far field patterns and spectral distribution
• Wall plug efficiency and output power
• Polarization
• Emitter-resolved analysis of diode laser bars
• “Smile" measurement and strain analysis

Spectral Design

• External resonators (Fiber Bragg Gratings, Volume Gratings) for frequency stabilization
• Dense wavelength multiplexing
• Analysis of thermal wavelength shift
• Design and manufacturing of Volume Gratings

High Power Diode Laser Systems

• Beam shaping of single emitters and laser bars
• Systems based on Broad Area Lasers, (DBR) Tapered Lasers, Ridge Lasers and Quantum Dot Lasers
• Spatial multiplexing of single emitters for multimode fiber coupling
• Beam transformation and multimode fiber coupling of laser bars
• Fiber coupling of single mode emitters
• Super-pulsed diode lasers
• Algorithms for automated assembly of micro optics

Adams, M., Holly, C., Rauch, S., Traub, M., Hoffmann D., Haefner, C.:
Multiphysics analysis of chip and resonator designs for increased damage threshold of external cavity high-power laser diodes.
OPTICS EXPRESS 32(4), 6446-6462, (2024)
https://doi.org/10.1364/OE.503081 (Open Access)

Schossau, M., Hofmann, O, Bonhoff, A., Adams, M., Stollenwerk, J., Holly, C.:
Modeling of External Feedback in Semiconductor Lasers for Continuous-Variable Quantum Key Distribution Systems.
125. Jahrestagung der Deutschen Gesellschaft für angewandte Optik, 21. Mai - 25. Mai 2024, Aachen. DGaO Proceedings, 125_b5, (2 S.), (2024)
https://www.dgao-proceedings.de/download/125/125_b5.pdf

Adams, M., Holly, C., Rauch, S., Traub, M., Hoffmann D.:
Evaluation of design concepts for feedback-resistant 9xx-nm high-power laser diodes.
SPIE LASE 2023 | San Francisco, California, United States | 28 January - 3 February 2023.
Proceedings Volume 12403, High-Power Diode Laser Technology XXI, 124030B, (9 S.) (2023)
https://doi.org/10.1117/12.2647171

Klein, S., Adams, M., Traub, M., Biermann, T., Hoffmann, H., Häfner, C.,
Industry and academia: pursuing a PhD at Fraunhofer, the best of both worlds.
SPIE LASE, 2023, San Francisco, California, United States, 28 January - 3 February 2023 San Francisco, CA, US.
Proceedings Volume 12401, High Power Lasers for Fusion Research VII; 124010B (2023)
http://dx.doi.org/10.1117/12.2664343

Traub, M., Wissenberg, S., Westphalen, T., Klein, S., Ammersbach, J., Livrozet, M., Gronloh, B., Esser, D., Giesberts, M., Faidel, H., Mohr, D., Hoffmann, H., Haefner, C. L.:
Highly reliable diode laser pump sources for the space qualified MERLIN laser platform and future wind LiDAR missions.
SPIE LASE, 28.1.-2.2.2023, San Francisco, California, United States. Proceedings Volume 12403, High-Power Diode Laser Technology XXI; 124030A (2023)
https://doi.org/10.1117/12.2657282

Adams, M., Holly C., Rauch S., Traub M.,
Analysis of the Non-Injecting Mirror Concept for Feedback-Resistant High-Power Laser Diodes with a Multiphysics Model.
CLEO: Science and Innovations 2022, San Jose, California United States, 15–20 May 2022. Technical Digest Series, paper SS2D.1 (2 S.), (2022).

Adams M., Rauch S., Holly C., Traub M., Hoffmann D.:
Multiphysics modeling of feedback-induced catastrophic optical damage in 9xx-nm high-power laser diodes.
SPIE LASE 2022 | San Francisco, California, United States | 22 Jan. - 28 Feb. 2022. Proceedings Volume 11983, High-Power Diode Laser Technology XX, 119830E, (9 S.) (2022) https://doi.org/10.1117/12.2608103

Adams, M., Holly C., Rauch S., Schwarz T., Traub M.:
Modeling of influencing factors driving thermal runaway in 9xx-nm high-power laser diodes.
27th International Semiconductor Laser Conference (ISLC) 2021, 10-14 Oct. 2021, Potsdam, Germany. Proc. of 2021 27th International Semiconductor Laser Conference (ISLC), 1-2 - (2021) http://dx.doi.org/10.1109/islc51662.2021.9615699

Adams M., Rauch S., Holly C., Traub M., Hoffmann D.:
Modeling of the impact of current crowding on catastrophic optical damage in 9xx-nm high power laser diodes.
SPIE Photonics West, LASE, High-Power Diode Laser Technology XIX, 6-12 MARCH 2021, online only.
Proceedings Volume 11668, High-Power Diode Laser Technology XIX; 116680C (9 S.),(2021)
https://doi.org/10.1117/12.2578092

Adams, M., Holly, C., Rauch, S., Traub M.:
GPU-Accelerated Wave-Optical Model for External-Cavity Diode Lasers.
OPTICS LETTERS 46, 1780-1783 (2021)
https://doi.org/10.1364/OL.419225

Klein, S., Giesberts, M., Traub, M., Fitzau, O., Hoffmann, D.:
Frequency stabilization of multimode diode lasers with fiber Bragg gratings.
High Power Diode Lasers and Systems Conference (HPD), 9-10 Oct. 2019 Coventry, United Kingdom, United Kingdom. 2019 IEEE High Power Diode Lasers and Systems Conference (HPD), (2 S.) (2019)  https://doi.org/10.1109/HPD48113.2019.8938607

Adams, M., Rauch, S, Holly, C., Bussek, T., Traub, M., Hoffmann, D.:
GPU-Accelerated Wave-Optical Simulation of Beam-Transformation System for High-Power Diode Lasers.
High Power Diode Lasers and Systems Conference (HPD), 9-10 Oct. 2019 Coventry, United Kingdom, United Kingdom. 2019 IEEE High Power Diode Lasers and Systems Conference (HPD), (2 S.) (2019) https://doi.org/10.1109/HPD48113.2019.8938673

Neumann, A., Giesberts, M., Witte, U., Fitzau, O., Hoffmann, H.-D.:
Analytical model for diode-to-fiber coupling and beam propagation in weakly guiding fibers.
2017 IEEE High Power Diode Lasers and Systems Conference (HPD), 11 Oct - 12 Oct 2017, Coventry, UK. Proc. IEEE High Power Diode Lasers & Systems, 35-36 (2017)
https://doi.org/10.1109/HPD.2017.8261091

Witte, U., Schneider, F., Holly, C., Di Meo, A., Rubel, D., Boergmann, F., Traub, M., Hoffmann, D., Drovs, S., Brand, T., Unger, A.:
kW-class direct diode laser for sheet metal cutting based on commercial pump modules.
High-Power Diode Laser Technology XV, San Francisco, California, United States, 28. Januar – 2. Februar 2017. Proc. SPIE Vol. 10086 (13 S.) (2017)
https://doi.org/10.1117/12.2252145

Schimmel, G., Janicot, S., Hanna, M., Decker, J., Crump, P., Erbert, G., Witte, U., Traub, M., Georges, P., Lucas-Leclin, G.:
Coherent beam combining architectures for high power tapered laser arrays.
PROCEEDINGS OF SPIE 10086, 1-11 (2017)
https://doi.org/10.1117/12.2252125

Witte, U., Traub, M.:
Cost efficient diode laser beam source for sheet metal cutting.
LASER TECHNIK JOURNAL 14
36-39 (2017)

Fraugeron, M., Klein, S., Vilera, M., Kochem, G., Perez-Serrano, A., Krakowski, M., Traub, M.:
Laser module based on monolithically integrated MOPAs at 1.5 μm for space-borne lidar applications.
ICSO 2016. International Conference on Space Optics. Biarritz, France, 18 - 21 October 2016. Paper 156 
1-8 (2016)

Witte, U., Schneider, F., Traub, M., Hoffmann, D., Drovs, S., Brand, T., Unger, A.:
kW-class direct diode laser for sheet metal cutting based on DWDM of pump modules by use of ultra-steep dielectric filters.
OPTICS EXPRESS 24, 22917-22929 (2016)

Hengesbach, S., Klein, S., Holly, C., Witte, U., Traub, M., Hoffmann, D.:
Simultaneous frequency stabilization and high-power dense wavelength division multiplexing (HP-DWDM) using an external cavity based on volume Bragg gratings (VBGs).
PROCEEDINGS OF SPIE 9733
SPIE 1-15 (2016)

Schimmel, G., Doyen, I., Janicot, S., Hanna, M., Georges, P., Lucas-Leclin, G., Decker, J., Crump, P., Erbert, G.: Kaunga-Nyirenda, S., Moss, D., Bull, S., Larkins, E. C., Witte, U., Traub, M.:
High-power operation of coherently coupled tapered laser diodes in an external cavity.
PROCEEDINGS OF SPIE 9733, SPIE 1-11 (2016)

Witte, U., Traub, M., Di Meo, A., Hamann, M., Rubel, D., Hengesbach, S., Hoffmann, D.:
Compact 35μm fiber coupled diode laser module based on dense wavelength division multiplexing of NBA mini-bars.
PROCEEDINGS OF SPIE 9733
SPIE 1-12 (2016)

Esquivas, I., Pérez-Serrano, A. , Tijero, J. M. G. , Faugeron, M., Krakowski, M. , van Dijk, F. , Kochem, G., Traub, M., Adamiec, P. , Barbero, J., Al, X., Rarity, J., Quatrevalet, M., Ehret, G.:
LIDAR system based on a high brightness semiconductor laser and single photon counting detection for space-borne atmospheric CO2 monitoring.
9a Reunión Espanola de Optoelectrónica OPTOEL'15, Salamanca, Spain, OPTOEL'15, July 13-July 15, 2015. Salamanca : CLPU 1-6 (2015)

Klein, S., Hengesbach, S., Traub, M., Hoffmann, D.:
Frequency stabilisation of single emitters and the effect on the beam quality.
2015 IEEE High Power Diode Lasers and Systems Conference (HPD) : [Proceedings] - IEEE, 2015
13-14 (2015)

Rubel, D., Witte, U., Hengesbach, S., Traub, M., Hoffmann, D.:
Characterisation of ultra-narrow band filters for diode laser systems based on dense wavelength division multiplexing.
2015 IEEE High Power Diode Lasers and Systems Conference (HPD), 14-15 Oct. 2015, 15-16 (2015)

Witte, U., Hamann, M., Di Meo, A., Rubel, D., Traub, M., Hoffmann, D.:
High power diode laser with 23W ex 35 μm fibre.
2015 IEEE High Power Diode Lasers and Systems Conference (HPD), 14-15 Oct. 2015
17-18 (2015) DOI: 10.1109/HPD.2015.7439673

Pérez-Serrano, A., Vilera, M., Esquivias, I., Faugeron, M., Krakowski, M., van Dijk, F., Kochem, G., Traub, M., Adamiec, P., Barbero, J., Ai, X., Rarity, J. G., Quatrevalet, M., Ehret, G.:
Atmospheric CO 2 remote sensing system based on high brightness semiconductor lasers and single photon counting detection.
PROCEEDINGS OF SPIE 9645, SPIE 1-10 (2015)

Decker, J., Crump, P., Fricke, J., Maabdorf, A., Traub, M., Witte, U., Brand, T., Unger, A., Erbert, G., Trankle, G.:
25-W Monolithic Spectrally Stabilized 975-nm Minibars for Dense Spectral Beam Combining.
IEEE PHOTONICS TECHNOLOGY LETTERS 27
1675-1678 (2015)

Witte, U., Rubel, D., Traub, M., Hamann, M., Hengesbach, S., Hoffmann, D.:
Dense wavelength multiplexing and 35 µm-fiber coupling of wavelength chirped high power diode laser bars.
Advanced Solid State Lasers Conference 2015. Berlin, Germany, October 4-9, 2015. Paper AF1A.6
1-3 (2015)

Faugeron, M., Vilera, M., Krakowski, M., Robert, Y., Vinet, E., Primiani, P., Le Goec, J.-P., Parillaud, O., Pérez-Serrano, A., Tijero, J. M. G., Kochem, G., Traub, M., Esquivias, I., van Dijk, F.:
High power three-section integrated Master Oscillator Power Amplifier at 1.5 µm.
IEEE PHOTONICS TECHNOLOGY LETTERS 27
1449-1452 (2015)

Klein, S., Hengesbach, S., Westphalen, T., Traub, M., Hoffmann, D.:
Suppression of cross coupling in an external resonator for a diode laser bar with 19 single emitters.
OPTICS LETTERS 40
641-644 (2015)

Esquivias, I., Pérez-Serrano, A., Tijero, J. M. G., Faugeron, M., van Dijk, F., Krakowski, M., Kochem, G., Traub, M., Barbero, J., Adamiec, P., Ai, X., Rarity, J., Quatrevalet, M., Ehret, G.:
RANDOM-MODULATION CW LIDAR SYSTEM FOR SPACE-BORNE CARBON DIOXIDE REMOTE SENSING BASED ON A HIGH-BRIGHTNESS SEMICONDUCTOR LASER.
International Conference on Space Optics , La Caleta, Tenerife , Spain , ICSO 2014, Oct. 7-10, 2014
1-8 (2014)

Hengesbach, S., Hoffmann, D., Traub, M., Poprawe, R.:
Comparison of edge emitter and vertical emitter based diode lasers for materials processing.
Proceedings 33rd Int. Congress on Applications of Lasers & Electro-Optics (ICALEO), October 19-23, 2014, San Diego/Ca., USA Paper 304, 1-9 (2014)

Holly, C., Hengesbach, S., Traub, M., Hoffmann, D.:
Numerical analysis of external feedback concepts for spectral stabilization of high-power broad-area semiconductor lasers.
PROCEEDINGS OF SPIE 8965, 1-8 (2014)

Hengesbach, S., Holly, C., Krauch, N., Witte, U., Westphalen, T., Traub, M., Hoffmann, D.:
High-Power Dense Wavelength Division Multiplexing (HP-DWDM) of frequency stabilized 9xx diode laser bars with a channel spacing of 1.5 nm.
PROCEEDINGS OF SPIE 8965, 1-9 (2014)

Esquivias, I., Consoli, A., Krakowski, M., Faugeron, M., Kochem, G., Traub, M., Barbero, J., Fiadino, P., Ai, X., Rarity, J., Quatrevalet, M., Ehret, G. :
High-brightness all semiconductor laser at 1.57 µm for space-borne lidar measurements of atmospheric carbon dioxide: device design and analysis of requirements.
PROCEEDINGS OF SPIE 9135
SPIE 1-8 (2014)

Westphalen, T., Hengesbach, S., Holly, C., Traub, M., Hoffmann, D.
Automated alignment of fast-axis collimator lenses for high-power diode laser bars.
Proc. of SPIE 8965, 1-6 (2014)

N. Michel, M. Calligaro, Y. Robert, M. Lecomte, O. Parillaud, M. Krakowski, T. Westphalen, M. Traub
High wall-plug efficiency diode lasers with an Al-free active region at 975 nm.
PROCEEDINGS OF SPIE 7198
71981-71981 (2009)

M. Haverkamp, G. Kochem, K. Boucke:
Single mode fiber coupled tapered laser module with frequency stabilized spectrum.
Proc. SPIE 6876
68761-68761 (2008)

M. Leers, K. Boucke, M. Götz, A. Meyer, M. Kelemen, N. Lehmann, F. Monti di Sopra:
Thermal resistance in dependence of diode laser packages.
High power diode laser technology and applications VI. January 19-24, 2008. San Jose, Ca. /USA 6876
1-10 (2008)

C. Wessling, S. Hengesbach, J. Geiger, J. Dolkemeyer, M. Traub, D. Hoffmann:
50 W passively cooled, fiber coupled diode laser at 976 nm for pumping fiber lasers using 100 µm fiber bundles.
Proc. SPIE 6876
1-11 (2008)

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