Abstract: An optical pulse position modulator is provided by a diffraction grating (or other optical spectrum resolution device) in combination with a suitable control device, such as a triangular electrooptic prism. This control device introduces a frequency dependent phase shift in the optical pulse which is proportional to the difference between the frequency of each Fourier component of the pulse and the central frequency. Thereby, upon reconstruction of the pulse by reflection back to the diffraction grating, the pulse position is shifted in time according to the controlled phase shift. Such a device has a relatively higher efficiency than conventional optical delay lines for picosecond pulses in the visible region of the spectrum, for example.