High-power 980 nm quantum dot broad area lasers

High-power quantum dot broad area lasers emitting at 980 nm are presented. Continuous-wave output powers of 4.3 W from a 50 /spl mu/m stripe width laser and of 6.3 W from a 100 /spl mu/m stripe width laser were achieved at 15/spl deg/C     

High-power quantum dot lasers with improved temperature stability of emission wavelength for uncooled pump sources

915 nm quantum dot lasers with temperature stable emission wavelengths have been realised for uncooled high-power applications. Broad area lasers with optimised dot geometry exhibit a thermal induced wavelength shift of 0.09 nm/K, which is 3.5 times lower than for quantum well lasers. Despite this improvement the lasers show high output powers of more than 3 W and wallplug efficiencies of 55% in continuous-wave operation.     

GaAs-based four-channel photonic crystal quantum dot laser module operating at 1.3 /spl mu/m

A GaAs-based laser module, which combines the output of four singlemode lasers operating at 1.3 /spl mu/m by using photonic crystal mirrors and combiners, has been developed. The complete device size is around 0.2 mm/sup 2/. The lasers can be operated individually or in parallel with sidemode suppression ratios better than 20 dB.     

Coherent InGaAs/GaAs laser arrays with laterally coupled distributed feedback gratings

A new approach for coherent positive index guided distributed feedback lasers array using laterally coupled gratings is demonstrated. The device fabrication requires no regrowth which makes this concept suitable for a variety of material systems. The lasers are based on an InGaAs/GaAs single quantum well structure emitting around 980 nm with high sidemode suppression ratio of more than 50 dB.     

Singlemode tapered quantum dot laser diodes with monolithically integrated feedback gratings

Based on a single InGaAs/GaAs quantum dot layer as active region, tapered laser diodes with laterally complex coupled grating emitting near 920 nm were fabricated for wavelength controlled optical pump applications. Output powers > 500 mW at room temperature and side- mode suppression ratios >35 dB are demonstrated.     

Gain, index variation, and linewidth-enhancement factor in 980-nm quantum-well and quantum-dot lasers

An experimental comparative study of the gain, index variation, and linewidth enhancement factor in 980-nm quantum-well (QW) and quantum-dot (QD) lasers structures, designed for high power applications, is presented. The gain spectra of the QW lasers at high injection level revealed three different transition energies, with a low linewidth enhancement factor (/spl sim/1.2) for E2HH2 transitions. Similar values for the linewidth enhancement factor, ranging between 2.5 and 4.5, were found for QW and QD devices, when comparing at similar values of the peak gain. This result is attributed to the contribution of excited state transitions in the measured QD lasers.     

Modal Analysis of Large Spot Size, Low Output Beam Divergence Quantum-Dot Lasers

Large spot size ridge waveguide lasers utilizing a low modal gain single quantum dot layer emitting at 925 nm were designed and fabricated. Ridge waveguides with width <3 mum emit in a single transverse mode with a low transverse full-width at half-maximum divergence of 20deg. Wider ridges initially lase in the first-order transverse mode before collapsing to the fundamental mode. This characteristic is explained by a thermally induced increase in the refractive index of the waveguide core. All lasers operate in a single lateral mode