PHP - Json class and urlencode

Question

I use Services_JSON class download form PEAR

when i call Services_JSON::encode() and get a string

i see my link before encode like that

http://lh5.ggpht.com/_gBueIqC8cnk/Sv9FvDspVLI/AAAAAAAAAoY/-ShqI3H-Hsg/słońce32 opalenier.jpg

and after encode , look like that:

http:\/\/lh5.ggpht.com\/_gBueIqC8cnk\/Sv9FvDspVLI\/AAAAAAAAAoY\/-ShqI3H-Hsg\/s\u0142o\u0144ce32 opalenier.jpg

słońce32 opalenier.jpg <-> s\u0142o\u0144ce32 opalenier.jpg

Json encode also do url encode? and what is kind of u0142o u0144ce ??