Advanced kilowatt-class diode laser bars for pump applications
Diode laser bars with 1 cm aperture are deployed in high volumes in industrial and scientific applications and continuously improved performance is required. Recent research at the FBH into such bars has increased both optical output power to around 1 kW and conversion efficiency at high output to around 50…70%, for use in a range of pump applications. The understanding obtained and technology developed has allowed the FBH to offer solutions tailor-made to address challenges in various commercial applications. For example, ongoing FBH design and technology developments have enabled kW-class bars to be made available that deliver peak performance in multiple different applications in the pumping of solid-state lasers, from established solid-state amplifier materials (Nd:YAG or Yb:YAG crystals) to alternative materials (Yb:CaF2), for short pulse (100 µs), long pulse (2 ms) and continuous wave pump applications. Cooperation partners span from high technology SMEs, to large concerns. Exemplary results include demonstrations of 1 kW per bar in CW mode (15°C), 2 kW per bar in QCW mode (200 µs, 200 K), and long-pulse (2 ms) passively cooled stacks with high spatial brightness and conversion efficiency of 3.7 MW/cm2-srand 57% respectively.
Further information regarding FBH's high-power diode lasers.
P. Crump, M.M. Karow, S. Knigge, A. Maaßdorf, G. Tränkle, J. Lotz, W. Fassbender, J. Neukum, J. Körner, R. Bödefeld, J. Hein, "Progress in joule-class diode laser bars and high brightness modules for application in long-pulse pumping of solid state amplifiers", Proc. SPIE 10086, Photonics West, San Francisco, USA, Jan 28 - Feb 02, 100860E (2017).
S.G. Strohmaier, G. Erbert, A.H. Meissner-Schenk, M. Lommel, B. Schmidt, T. Kaul, M. Karow, P. Crump, "kW-class Diode Laser Bars", Proc. SPIE 10085, Photonics West, San Francisco, USA, Jan 28 - Feb 02, 100850F (2017).
C. Frevert, F. Bugge, S. Knigge, A. Ginolas, G. Erbert, P. Crump, "940nm QCW diode laser bars with 70% efficiency at 1 kW output power at 203K: analysis of remaining limits and path to higher efficiency and power at 200K and 300K", Proc. SPIE 9733, Photonics West, San Francisco, USA, Feb. 13-18, 97330L (2016).
In April 2017, Forschungsfabrik Mikroelektronik Deutschland (Research Fab Microelectronics Germany) was launched, funded by the Federal Ministry of Education and Research with up to 400 Mio. Euros over the next 3.5 years. This initiative aims to boost German developments in micro and nanoelectronics, thus providing the technological basis for future applications in production, energy, mobility as well as in communicatopns. FBH is a partner in this cross-institutional cooperation of Fraunhofer Group for Microelectronics and Leibniz institutes FBH and IHP, aiming to prevail in a competitive global market with advanced German R&D products.
For the first time ever, a Bose-Einstein condensate has been successfully created in space in January 2017. The MAIUS mission demonstrated that quantum optical devices can be operated even in such harsh environments – a prerequisite for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications. A compact and robust diode laser system for laser cooling and atom interferometry with ultra-cold rubidium atoms was developed. Core components were four hybrid-integrated master-oscillator power-amplifier laser modules developed by FBH, delivering spectrally pure and highly stable optical radiation.
A. Wicht, A. Bawamia, M. Krüger, Ch. Kürbis, M. Schiemangk, R. Smol, A. Peters, G. Tränkle, "Narrow linewidth diode laser modules for quantum optical sensor applications in the field and in space", Proc. SPIE 10085, Photonics West, San Francisco, USA, Jan 28 - Feb 02, 100850F (2017).
M. Schiemangk, K. Lampmann, A. Dinkelaker, A. Kohfeldt, M. Krutzik, C. Kürbis, A. Sahm, S. Spießberger, A. Wicht, G. Erbert, G. Tränkle, A. Peters, "High-power, micro-integrated diode laser modules at 767 and 780 nm for portable quantum gas experiments", Appl. Opt., vol. 54, no. 17, pp. 5332-5338 (2015).
E. Luvsandamdin, C. Kürbis, M. Schiemangk, A. Sahm, A. Wicht, A. Peters, G. Erbert, G. Tränkle, "Micro-integrated extended cavity diode lasers for precision potassium spectroscopy in space", Opt. Express, vol. 22, no 7, pp. 7790-7798 (2014).
M. Lezius, T. Wilken, C. Deutsch, M. Giunta, O. Mandel, A. Thaller, V. Schkolnik, M. Schiemangk, A. Dinkelaker, A. Kohfeldt, A. Wicht, M. Krutzik, A. Peters, O. Helmig, H. Duncker, K. Sengstock, P. Windpassinger, K. Lampmann, T. Hülsing, T.W. Hänsch, R. Holzwarth, "Space-borne frequency comb metrology", Optica, vol. 3, no. 12, pp. 1381-1387 (2016).
A.N. Dinkelaker, M. Schiemangk, V. Schkolnik, A. Kenyon, K. Lampmann, A. Wenzlawski, P. Windpassinger, O. Hellmig, T. Wendrich, E.M. Rasel, M. Giunta, C. Deutsch, C. Kürbis, R. Smol, A. Wicht, M. Krutzik, A. Peters, "Autonomous frequency stabilization of two extended-cavity diode lasers at the potassium wavelength on a sounding rocket", Appl. Opt., vol. 56, no. 5, pp. 1388-1396 (2017).
FBH has successfully demonstrated metal-insulator-semiconductor field-effect transistors (MISFETs) based on gallium oxide (β-Ga2O3), revealing the potential of this new material. By combining high-performance β-Ga2O3 epitaxy with optimized processing and high-quality Al2O3 ALD gate insulator technology, state-of-the-art devices could be realized. Leibniz Institute for Crystal Growth provided the substrates and homoepitaxial n-doped layers. FBH took care of a dedicated transistor layout and developed specific technological steps for Ga2O3 transistor fabrication. Finally, competitive MIS transistors with drain current levels up to 85 mA/mm and a pinch-off voltage of -23 V have been demonstrated. They showed very low sub-threshold drain and gate currents of less than 10-10 A/mm. Thus, the transistors have demonstrated the suitability of this new material for devices offering outstandingly low leakage currents and huge ION/OFF ratios of more than 109.
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