I automatically use the preposition "on" after the words "focus" or "emphasis". However, I've recently come across several instances of them being followed by "in", such as in the following examples:
She graduated with a degree in studio art, with a focus in printmaking.
He graduated with a degree in creative writing, with emphasis in fiction.
A quick Google search shows that this is pretty common. I'm not entirely convinced however, and I can't seem to find anything to support the use of "in" in dictionaries or style guides. Any help?