Cavity modelling in stacked quantum well slabs for optically pumped lasers

The paper discusses a model to estimate the diffraction loss in stacked quantum well slabs for optically pumped lasers. Two quantum well slabs, cleaved from the same strip, are stacked together with the front sides facing each other to form the laser cavity. Misalignment and different slab sizes are possible, which may result in additional diffraction loss. The model is based on the diffraction integral theory to calculate the fundamental mode in a plane mirror resonator. Model results suggest that, for a small misalignment size of a few percent of the wavelength, the diffraction loss is relatively small compared with other sources of loss in the laser system. Hence, the stacked scheme is feasible for the long wavelength far-infrared region but not suitable for shorter wavelengths in the mid- or near-infrared regions. This model is in general applicable to other optically pumped quantum well lasers.