Abstract: An integrated optics non linear coupler presents on a surface a first and a second waveguide (2, 3) coupled contradirectionally by means of a distributed feedback grating (10). The first waveguide (2) defines an input port (4) and a first output port (5) of the device (transmission output) and the second waveguide (3) defines a second output port (6) of the device (reflection output). By means of an optical control signal injected into the device together with an information signal, the device can be brought to conditions of non-linear operation, thus making the grating (10) switch from transmitting to reflecting behaviour or vice versa with respect to a given wavelength.