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5 W frequency stabilized 976 nm tapered diode laser

5 Watt frequenzstabilisierter Trapezlaser bei 976 nm
: Friedmann, P.; Gilly, J.; Moritz, S.; Ostendorf, R.; Kelemen, M.T.


Zediker, M.S. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
High-power diode laser technology and applications VI : 21 - 23 January 2008, San Jose, California, USA
Bellingham, WA: SPIE, 2008 (SPIE Proceedings Series 6876)
ISBN: 978-0-8194-7051-5
ISSN: 0277-786X
Paper 68761J
Conference "High-Power Diode Laser Technology and Applications" <6, 2008, San Jose/Calif.>
Fraunhofer IAF ()
high-brightness; hohe Brillanz; high power; hohe Leistung; diode laser; Diodenlaser; semiconductor laser; Halbleiterlaser; tapered laser; Trapezlaser; AlGaAs-InGaAs

More and more applications, like tunable frequency doubling of diode lasers for blue-green outputs, non linear spectroscopy, or pump laser sources for fiber lasers necessitate diffraction-limited tunable narrow linewidths and high output powers in the multiwatt regime. For these applications, tapered lasers based on a tapered amplifier with gain-guided design can be used in an external cavity set up to guarantee both - frequency stabilization and tunability.
We have realized frequency stabilized high-power ridge-waveguide tapered diode lasers with more than 4W of cw output power. These low modal gain, single quantum well InGaAs/AlGaAs devices emitting between 920nm and 1064nm were grown by molecular beam epitaxy. Tapered single emitters consist of an index-guided ridge section and a gain-guided taper section with an overall length of 3.5mm. The taper angle was 6°. With a high-reflectivity coating on the rear facet and an antireflection coating on the front facet more than 10W of output power have been demonstrated.
To optimize the beam quality at higher output power the two different sections have been operated by different operation currents. For this purpose the tapered diodes have been mounted p-side down on structured submounts. For wavelength tunability and frequency stabilization the tapered diodes, provided with AR coatings on both facets, have been used in external cavity setup in Littrow configuration. The influence of the different operation currents on the electro-optical and beam characteristics has been carefully investigated in detail. Within this operation mode a nearly diffraction limited behavior up to 5W has been established.