Raya is a name commonly used in Bulgaria as well. The meaning of the name is strongly related to the Bulgarian word for "heaven" which sounds pretty close to 'Raya' - RAI. In Bulgaria Raisa is not very popular for it sounds Russian indeed. Nevertheless Raya is considered one of our most beautiful although not most popular names.
In fact the name Raya (or Raja, Raia) is not used in Russia today (Raisa is their commonly used name). As it is in many cases - a truly Bulgarian name is confused with a Russian one.
Although I am a native Russian I've never heard Raya as a short form of Raisa. Raisa women are being called Rasha, just like Maria - Masha and Daria - Dasha. As far as I am informed Raya is a Bulgarian name.
-- Anonymous User 10/16/2005
Ditto the other two comments. Raya is a pet form of Rayna or Rangelina, but I don't think it has anything to do with Raisa. [noted -ed]
In fact the name Raya (or Raja, Raia) is not used in Russia today (Raisa is their commonly used name). As it is in many cases - a truly Bulgarian name is confused with a Russian one.