An optical Fourier transform device comprising: phase modulation means adapted to linearly chirp a signal optical pulse at a rate K; and a dispersive medium having a group-velocity dispersion and whose dispersion amount D is D=1/K, wherein the device is configured such that the chirped signal optical pulse emitted from the phase modulation means is made to pass through the dispersive medium, such that the temporal waveform of the optical pulse obtained at the output of the dispersive medium is proportional to the spectrum shape of the signal optical pulse; characterized by: an optical pulse generator comprising an optical pulse transmitter, wherein the optical pulse transmitter is adapted to be driven by a clock signal extracted from said signal optical pulse by a clock extraction circuit, and wherein said optical pulse generator is adapted to generate a control optical pulse of a shape expressed by a quadratic function or a parabola from an optical pulse generated by the optical pulse transmitter, wherein the device is configured such that said control optical pulse is synchronized with said signal optical pulse; and a coupler adapted to couple the signal optical pulse with the control optical pulse; wherein said phase modulation means is adapted to receive the coupled signal optical pulse and control optical pulse, and comprises an optical Kerr medium adapted to linearly chirp the signal optical pulse over the entire signal optical pulse by cross phase modulation between the signal optical pulse and the control optical pulse. phase modulation means adapted to linearly chirp a signal optical pulse at a rate K; and a dispersive medium having a group-velocity dispersion and whose dispersion amount D is D=1/K, wherein the device is configured such that the chirped signal optical pulse emitted from the phase modulation means is made to pass through the dispersive medium, such that the temporal waveform of the optical pulse obtained at the output of the dispersive medium is proportional to the spectrum shape of the signal optical pulse; characterized by: an optical pulse generator comprising an optical pulse transmitter, wherein the optical pulse transmitter is adapted to be driven by a clock signal extracted from said signal optical pulse by a clock extraction circuit, and wherein said optical pulse generator is adapted to generate a control optical pulse of a shape expressed by a quadratic function or a parabola from an optical pulse generated by the optical pulse transmitter, wherein the device is configured such that said control optical pulse is synchronized with said signal optical pulse; and a coupler adapted to couple the signal optical pulse with the control optical pulse; wherein said phase modulation means is adapted to receive the coupled signal optical pulse and control optical pulse, and comprises an optical Kerr medium adapted to linearly chirp the signal optical pulse over the entire signal optical pulse by cross phase modulation between the signal optical pulse and the control optical pulse. an optical pulse generator comprising an optical pulse transmitter, wherein the optical pulse transmitter is adapted to be driven by a clock signal extracted from said signal optical pulse by a clock extraction circuit, and wherein said optical pulse generator is adapted to generate a control optical pulse of a shape expressed by a quadratic function or a parabola from an optical pulse generated by the optical pulse transmitter, wherein the device is configured such that said control optical pulse is synchronized with said signal optical pulse; and a coupler adapted to couple the signal optical pulse with the control optical pulse; wherein said phase modulation means is adapted to receive the coupled signal optical pulse and control optical pulse, and comprises an optical Kerr medium adapted to linearly chirp the signal optical pulse over the entire signal optical pulse by cross phase modulation between the signal optical pulse and the control optical pulse.