We report on GaAs-based broad area (100 µm) 1.3 µm quantum dot (QD) lasers with high CW output power (5 W) and wall-plug efficiency (56%). The reliability of the devices has been demonstrated beyond 3000 h of CW operation at 0.9 W and 40 • C heat sink temperature with 2% degradation in performance. P-doped QD lasers with a temperature-insensitive threshold current (T 0 > 650 K) and differential efficiency (T 1 = infinity) up to 80 • C have been realized.

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We report on 980nm InGaAs∕AlGaAs lasers with a broad waveguide based on a longitudinal photonic band crystal concept. The beam divergence measured as full width at half maximum was as narrow as <5° (vertical). Broad area 100μm multimode devices demonstrated >15W pulsed operation as limited by the current source. Significantly increased modal spot size enabled stable single lateral mode operation in broad ridge 10μm stripes. Maximum continuous wave power in single mode regime of 1.3W for 10μm wide stripe lasers was obtained, being limited by the catastrophic degradation of the unpassivated laser facets.

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Wavelength-stabilized operation is realized in broad area quantum dot laser diodes with cleaved facets grown in the tilted cavity laser (TCL) design for the range up to 1.3 µm. For two different designs TCL wavelength is chosen to be either in the range of quantum dot excited state transitions (1.16 µm), or in the range of quantum dot ground state transitions (1.27 µm). The shift of the lasing wavelength is 0.165 nm K −1 in a temperature range between −200 • C and 70 • C. The spectral width of the lasing emission in broad area devices is 0.6 nm and the width (FWHM) of the far field is 4 • and 42 • for lateral and vertical directions, respectively.

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We report on 1.33 µm quantum dot (QD) lasers grown on GaAs substrates that show a modal gain of 45 cm −1 , low threshold current density of 150 A cm −2 and room-temperature continuous wave output power of 2.5 W. The active region is based on ten InAs/InGaAs/GaAs quantum dot layers formed by activated phase separation. High structural quality of the active region is achieved, owing to minimization of the total amount of strained material per QD layer. The optical confinement factor is increased by exploiting high Al composition (80%) in the cladding layers. A modal gain over 20 cm −1 in the 1315-1345 nm wavelength range is revealed by the Hakki-Paoli technique at a low current density of 500 A cm −2 .

The 1300 nm range vertical-cavity surface-emitting lasers with the active region based on InGaAs/InGaAlAs superlattice are fabricated using molecular-beam epitaxy and the double wafer-fusion technique. Lasers with the buried tunnel junction diameter of 5 μm have shown singlemode CW operation with the output optical power of ∼6 mW at 20°C. Opened eye diagrams are observed up to 10 Gbps.