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We present a comparison of epitaxial designs for non-resonantly pumped vertical external cavity surface-emitting
lasers for emission in the red spectral range around 665 nm. Here, the VECSEL chip is based on a metal-organic
vapor-phase epitaxy grown (GaxIn1-x)0.5P0.5/[(AlxGa1-x)yIn1-y]0.5P0.5 multi-quantum-well structure with 20
compressively-strained quantum wells. The wells are placed in packages in a separate confinement heterostructure
with quaternary AlGaInP barriers and cladding layers, respectively. The active region is fabricated on a 55 λ/4
pairs Al0.50Ga0.50As/AlAs distributed Bragg reflector. We compare two designs with different quantum well
distributions in the chip: one design which includes 4 quantum wells in 5 packages whereas the other contains
10 quantum well pairs to have a larger absorption length. Laser parameters like output power, differential
efficiency and threshold pump power of the different chip designs measured in a v-shaped cavity configuration
are examined. By using the 10 × 2 quantum well distribution in the chip, we could improve the absorption
efficiency by nearly 40% and output power by 25% compared to the 5 × 4 design. Additionally, by introducing
tensile strained quaternary barriers and cladding layers in the 5 × 4 QW design, we could compensate for the
compressive strain introduced by the quantum wells. Photoluminenscence measurements of structures with
different numbers of quantum well packages reveal a more homogenous quantum well growth due to the strain-compensation
technique. Furthermore, with the strain compensation technique, the output power could be
increased over 30% compared to our conventional structures.
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