MBE grown optically pumped semiconductor disk lasers emitting at 940 nm

We present the optimization and performance of high-power optically pumped semiconductor disk lasers emitting near 940 nm. The emission efficiency at this wavelength is typically low owing to the poor carrier confinement within the shallow GaInAs quantum wells especially at high injection levels. Our work was focused on studying the efficiency of three types of structures with barrier materials made of AlGaAs, GaAs and GaAsP, providing different band offsets. The structures were grown by solid-source molecular beam epitaxy and consisted of a 30.5 pair AlAs/AlGaAs distributed Bragg reflector and an active region comprising 10 groups of triple-quantum-wells. To improve the crystal quality we have applied rapid thermal annealing for each grown wafer. The gain chips were then capillary bonded with water to a type IIa natural diamond heat spreader. The bonded gain elements were tested in a laser cavity with a linear-cavity configuration. Using a 3% output coupler we have obtained a maximum output power of 3 W from the structure with GaInAs/GaAsP composition. The corresponding M2 value was 1.5 and the optical-to-optical conversion efficiency was 10%.