Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 34: Semiconductor Laser

HL 34.11: Vortrag

Mittwoch, 27. Februar 2008, 17:00–17:15, EW 202

High Performance AlGaInAs Quantum Dot Lasers in the Visible Wavelength Region (λ =760 nm) — •Sven Gerhard, Thomas W. Schlereth, Wolfgang Kaiser, Sven Höfling, and Alfred Forchel — Technische Physik Universität Hubland 97074 Würzburg

Since the commonly for quantum dot (QD) lasers employed GaInAs QDs do not allow for laser operation below ≈ 900 nm which is essential for a number of applications we incorporated the high bandgap material AlAs into GaInAs QDs forming Al_xGa_1−x−yIn_yAs QDs to reach short wavelengths. It was recently shown for 920 nm QD lasers that the insertion of Al into GaInAs QDs leads to lower threshold current densities J_th and increased material gain due to decreased QD sizes and increased QD densities [1]. We fabricated broad area (BA) lasers and distributed feedback (DFB) lasers based on Al_xGa_1−x−yIn_yAs QDs emitting in the wavelength region of ≈ 760 nm. The BA devices exhibit a high internal quantum efficiency η_i of 87 %, an absorption α_i of ≈ 6 cm⁻¹, a transparency current density J_tr of 132 Acm⁻² and a modal gain coefficient Γg₀ of ≈ 37 cm⁻¹. The DFB laser diodes show typical threshold currents I_th of 32 mA and slope efficiencies of 0.3 W/A. Exhibiting a single emission line at 763.7 nm with a sidemode suppression ratio (SMSR) of at least 40 dB and single mode operation with output powers up to 25 mW per facet these DFB devices are suitable for oxygen gas detection.

References: [1] T.W. : Schlereth et al. Applied Physics Letters 90, 221113 (2007)