  Single-photon emitters integrated into quantum optical circuits will enable
new, miniaturized quantum optical devices. Here, we numerically investigate
semiconductor quantum dots embedded to low refractive index contrast
waveguides. We discuss a model to compute the coupling efficiency of the
emitted light field to the fundamental propagation mode of the waveguide, and
we optimize the waveguide dimensional parameters for maximum coupling
efficiency. Further, we show that for a laterally cropped waveguide the
interplay of Purcell-enhancement and optimized field profile can enhance the
coupling efficiency by a factor of about two.
