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High-power high-brightness ridge-waveguide tapered diode lasers at 940 nm

Hochleistungs-Trapez-Diodenlaser hoher Brillanz mit Rippenwellenleiterstruktur bei 940 nm
: Kelemen, M.T.; Rinner, F.; Rogg, J.; Wiedmann, N.; Kiefer, R.; Walther, M.; Mikulla, M.; Weimann, G.


Chin, A.K. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Test and measurement applications of optoelectronic devices : 21 - 22 January 2002, San Jose, USA
Bellingham/Wash.: SPIE, 2002 (SPIE Proceedings Series 4648)
ISBN: 0-8194-4387-5
Conference "Test and Measurement Applications of Optoelectronic Devices" <2002, San Jose/Calif.>
Fraunhofer IAF ()
high brightness; hohe Brillanz; high power; high-power diode laser; Hochleistungs-Diodenlaser; tapered laser; Trapezlaser; laser diode; Diodenlaser; life time; Lebensdauer; AlGaAs/InGaAs; semiconductor; Halbleiter

Semiconductor lasers with high beam quality and high optical output power are very attractive for a variety of applications such as optical pumping of solid-state lasers, fiber amplifiers and medical treatment. When easy and low-cost fabrication is a further requirement, devices based on tapered gain sections are the most promising candidates. Low model gain, single quantum well InGaAs/AlGaAs devices emitting at 940 nm were grown by molecular beam epitaxy. The lateral design consists of a tapered gain guided and a ridge-waveguide section having an overall length between 2 mm and 3 mm. Whereas the length of the tapered structure determines the high output power, the high brightness requires a ridge-waveguide structure with sufficient length. Here the length of the ridge section has been chosen to 500 µm. We achieved an optical output power of up to 5.3 W at room temperature in continuous wave mode. The threshold current density depends on the tapered length with values between 200 A/cm2 and 650 A/cm2. The slope efficiency is around 0.9 W/A for all devices. The wall plug efficiency reaches 44 % at a current of 3 A. The beam quality factor remains nearly constant up to about 2.2 W having an M2-value of 1.3. At higher optical output powers M2 increases fast. The lifetime of such devices has been extrapolated to more than 7500 h at room temperature.