  In this paper, we review the state of the art of mode selective, integrated
sum-frequency generation devices tailored for quantum optical technologies. We
explore benchmarks to asses their performance and discuss the current
limitations of these devices, outlining possible strategies to overcome them.
Finally, we present the fabrication of a new, improved device and its
characterization. We analyse the fabrication quality of this device and discuss
the next steps towards improved non-linear devices for quantum applications.
