Abstract: A Sagnac-type fiber-optic gyroscope having a light source, a fiber coil consisting of an optical fiber, a receiver arrangement which are all connected with gates of a directional coupler, in which the light fed into the fiber coil interferes with the light emerging from the fiber coil in a coupling area and the rate of rotation of the fiber-optic gyroscope is determined from the interference signals. In order to achieve a working point which is situated in or close to the quadrature point, the directional coupler is developed as a 4.times.4 coupler between the arms of which fixed phase relations are provided in the coupling area.