Please also have a look at the new examples I just added to the OptiX 7 Advanced Samples showing how to implement different light types.
https://forums.developer.nvidia.com/t/optix-advanced-samples-on-github/48410/8?u=droettger
These allow placing different singular and area lights into a scene and it would be simple to mimic the above screenshot with some runtime generated or loaded objects and a single rectangle area light.