Raku is actually the name of a style of Japanese pottery, first created in the 1500's for use in the tea ceremony.
The famous tea master Sen no Rikyū commissioned a palace tile maker named Chōjirō to create a series of hand-built tea bowls in an imperfect style (as to reflect the ideals of wabi sabi) which was popular among Japan's aristocracy.
The shogun Hideyoshi was so impressed with Chōjirō's work that he awarded him the seal "Raku", which roughly translates to "pleasure". Eventually the family adopted the name Raku.
The Raku family still makes pottery to this day.