Go to his office hours, definitely. A common trap I've seen a lot of students fall into is that they think they can't approach a professor until they are impressive enough (have enough personal side projects, have read enough of their papers, have perfect grades in their class, etc), or they try too hard to appear more knowledgeable than they are. It's totally fine to just go and say "I'm interested in this, do you have any advice on what I should do to learn more?". You'll have a better time impressing him by following up on that advice successfully than you will trying to make a side project on your own.