There are several Johanssons who have created glass in Sweden recently. There's Willy and Wilhelm, both Hadelands, and Jan and Berit, Orrefors. However, all of them have a double "s" after the "n" and I see only one "s" on yours, so I don't think it's any of them. (In terms of style, it looks like something a young Jan Johansson might have done.)
P.S. Just to confuse things: After I posted, I googled W. Johanson and was led to this site, http://anitasfinearts.com/english/scandglass.html
, which shows two pieces by W. Johanson, Orrefors, numbers 7 and 11. Everything else about the site looks very reputable. However, neither the Orrefors books by Duncan and Wickman list W. Johanson as a designer at Orrefors, and the same is true of the Pina books.