I have never heard Tesla used as a girls' name. It's a Serbian surname and most commonly heard refering to the scientist and electrical engineer, Nikola
Tesla and his coil transformer which is sometimes called the Tesla machine:http://www.neuronet.pitt.edu/~bogdan/tesla/
"Tesla's surname dates back more than two and a half centuries... The name Tesla ... in a purely literal sense, is a trade name like Smith... or Carpenter. As a common noun it describes a woodworking tool which, in English, is called an adz. This is an axe with a broad cutting blade at right angles to the handle, instead of parallel as in the more familiar form. It is used in cutting large tree trunks into squared timbers. In the Serbo-Croat language, the name of the tool is tesla." (From PRODIGAL GENIUS: The Life of Nikola
J. O'Neill (1944))
There is also an 80's song by OMD called 'Tesla Girls', but other than its references to electricity, it has little to do with Tesla.