Magneto optical devices have many applications including optical Faraday isolators or circulators for telecommunications and sensors for both electrical and magnetic fields. The research for new powerfull sensors has pushed the bondaries in materials science in order to obtain stable enough new glass compositions presenting outstanding magneto-optical properties. Such requirements are necessary  to  transform these glasses into larger devices (in order to substitute single crystals) or prepare optical fibers, for exemple. This paper will overview the development of magneto optial devices in the last years as well as will point out  for future applications. Besides, we will present the development of new paramagnetic glassy materials containing transition metal oxides as well as rare earth ions and their use to produce discrete field sensors and special optical fibers.