Can you clarify your question? If you're asking about all visual representations the answer is much more difficult than if you're talking about erotica in its usual sense of 'written with intent to arouse.'

If you're just curious about works with the aggressive intention of arousing rather than amusing the reader/viewer or providing a vehicle from which to criticize religion or politics, the answer is quite late, with John Cleland's Fanny Hill, though earlier models such as The School of Girls (l'escolle des filles) and Luisea Sigea could also serve as examples you could argue for.