Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 34: Semiconductor Laser

HL 34.6: Vortrag

Mittwoch, 27. Februar 2008, 15:30–15:45, EW 202

Temperature stable 920-nm quantum dot material for high power laser applications — •Emil Mihai Pavelescu and Johann Peter Reithmaier — Technische Physik, Institute of Nanostructure Technologies and Analytics, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany

Besides high output powers, a stable emission wavelength is the main prerequisite for using laser diodes to pump solid state lasers or fiber amplifiers, such as ytterbium at the 920 nm wavelength range. Using a less temperature sensitive gain material, such as InGaAs/GaAs quantum dots, 920-nm laser diodes with a higher acceptable tolerance of their operation temperature were realized.The laser structure was grown by solid source molecular-beam epitaxy and consists of 820 nm core waveguide composed of GaAs/Al0.57Ga0.43As short period superlattices and 1600 nm thick Al0.60Ga0.40As cladding layers. The InGaAs self-organized quantum dots were formed at 500 °C by an alternating submonolayer deposition of InAs and In0.16Ga0.84As, corresponding to a nominal indium content of 52 % and a thickness of 5.4 monolayers. At room temperature the lasers showed good properties with lasing wavelengths near 920 nm. The laser structure had a strong dependence of its lasing wavelength with cavity length, a finger print of QD lasers due to a broader gain as compared to QW lasers. Notably, the lasers revealed small coefficients (< 0.19 nm/K) of wavelength variation with temperature, whose values decreased with increasing cavity length down to a remarkably value of around 0.08 nm/K.