What poets? Coleridge/Baudelaire/De Quincey/Ginsberg? Not a whole lot if you ask me...
Can you name a few more?
I am very sorry, I have overseen your post!!!
Baudelaire disliked drugs as he thought that inspiration must come from one self...
But: Wilde, Novalis (and most from the German romantic era), Goethe (I believe), Dumas, Poe, Doyle, Blake, ...
(OK they are not all poets) There are a lot of them, and even more allusions to opium in many pieces of great art.
Opium is overestimated on here I think. It is by no means an entheogen, just a dreamy depressant with mild euphoric curves. It distants you from your environment.
It is for sure romantisized (like absinthe). And I don't believe to see any truth behind it (although I would love to be surprized), nevertheless exactly this effect has something romantic (dreamy state). I don't know. It is quite hard to get it...
Something I found on the net:
"In Flanders fields the poppies blow
Between the crosses, row on row
That mark our place; and in the sky
The larks, still bravely, singing, fly
Scarce heard amid the guns below.
We are the Dead. Short days ago
We lived, felt dawn, saw sunset glow,
Loved and were loved, and now we lie
In Flanders fields".