Late Niklas Luhmann (he died 1998) was a german sociologist with some influence. From Bielefeld he tried to change sociology as opponent of Jürgen Habermas with his systems theory, one of the grand theory approaches. Systems Theory means, that you stop to look at the individual or the group of individuals in sociology but look instead on greater social systems - like the media system, the political system, the economic system, the scientific system, and so on. The smallest element of each of these systems isn't the human being or the action, but communication. For example, in the economic system communication is seen as the flow of money (or 'paying events'). Every system does only know itself, and it's picture of it's environment - the economic system only cares about money, and everything else is seen in that language.

One could go in more details about systems theory - from the origins in the mathematical theories of Spencer Brown (the law of form) to the relations to radical constructivsm, but I think for a first glance at Luhmann this should be enough. Of course, his grand theory was as well influential on german sociology as well as polarising the sociologists in pro-Luhmann and contra-Luhmann.