I recently read Morton Smith’s article “II Isaiah and the Persians,” which is quite enlightening for the study of Deutero-Isaiah. Smith argues that Deutero-Isaiah (specifically, Isaiah 40-48) is strongly influenced by Persian thought and, especially, Cyrus’ propaganda against Babylon.
Go check it out. You can find it in Journal of the American Oriental Society 83 (1963), 415-421, and Shaye J. D. Cohen, ed., The Cult of Yahweh, vol. 1 (Leiden: Brill, 1996), 73-83.