well if you go into the star wars novels, the empire developed cloaking devices but never perfected them. I think it was in the series with Grand Admiral Thrawn that they are used to cloak asteroids around coruscant so the New Republic can't safely use the planet. Also in the rebel assault games. I think the second one had phantom ties in it that had cloaking devices on them. Of course since you're only using info from the movies all this is irrelevant so I will stop my needless rambling
