Abstract: An opto-electronic device comprising a directional coupler provided with a first waveguide to receive incoming electromagnetic radiation, said first guide comprising a guiding region of electro-optic material. Moreover, the directional coupler comprises a second waveguide into which can be coupled at least a first portion of said incoming radiation and provided with a port for radiation being output. The opto-electronic device is equipped with a structure for generating a controlling electric field at least inside said first guide of the directional coupler and such as to cause in said electro-optic material polarization conversion of at least part of said incoming radiation. By means of this polarization conversion it is possible to control the power of the radiation being output from the second waveguide, producing a modulator, a changeover switch, an attenuator or an open-or-closed switch.