Who is author of Amar Bangla?

Amar Bangla was Written by Rabindranath Tagore

Amar Sonar Bangla ( "My Golden Bengal") is the national anthem of Bangladesh .An Ode to Mother Bengal, it was written by Bengali polymath Rabindranath Tagore in 1905. The melody of the hymn derived from the Baul singer Gagan Harkara's song "Ami Kothay Pabo Tare"
The song (Amar Bangla) was written in 1905 during the first partition of Bengal, when the ruling British Empire had an undivided India's province of Bengal split into two parts; the decision was announced on 19 July by the then-Viceroy of India Lord Curzon, taking effect on 16 October. This divide of Bengal, being along communal lines–East Bengal having a majority of Muslims and West Bengal having a majority of Hindus–is claimed to have undermined India's national movement against British imperialism and to have been politically motivated.