Does the word voltage exist in academic engineering?
Yes, voltage is a technical word in English.

From Wordnik:


  noun A measure of the difference in electric potential between two points in space, a material, or an electric circuit, expressed in volts. 


In fact, Wikipedia even lists "electric tension" as a synonym, though I hadn't heard that before. Mostly it's referred to as voltage or potential difference.

Some other answers have noted that Electric Tension was used to describe a potential difference until the mid-20th century in England, but it went out of popularity.

Google’s Ngram shows that voltage is far more popular than Electric Tension ever was, though.