Today, our pop culture is ridden with depictions of 'futuristic' super weapons: from satellite beam rays to mass EMP bombs - you name it.
But, to my understanding, pre 1945 pop culture, and society at large, was not aware of the concept of nuclear weapons until Hiroshima and Nagasaki. I've read a fair bit of 'classic sci-fi' and nuclear weapons only become a trope (or are mentioned at all) from 1945 thereafter.
Was society really unaware of the concept of nuclear weapons before they were effectively deployed in Japan?
In a loose sense, yes. Details here. There is a difference between having a loose idea of something being a form of science fiction, or technically maybe possible, and suddenly having it seem to spring into reality. The analogy I like to use is of a "warp drive" — basically everyone has some loose idea of what that means, a few people know there might be some theoretical ways of making one, but if suddenly the US government reported that it not only had made one but had done three laps around Mars, we'd all be pretty shocked.