To supplement the theories already given, the name
Svetlana was invented by philologist
Alexander Vostokov for his romance story '
Svetlana and
Mstislav' published 1802 (although it was the name's appearance later in
Vasiliy Zhukovsky's ballad
Svetlana that would popularise the name.)
Allegedly Vostokov liked to experiment with creating names and was a fan of studying place names (toponymy).
Sources:
https://ru.wikipedia.org/wiki/%D0%A1%D0%B2%D0%B5%D1%82%D0%BB%D0%B0%D0%BD%D0%B0https://en.wikipedia.org/wiki/Alexander_Vostokov