THE PRESENT INVENTION RELATES TO CONTINUOUSLY ADJUSTABLE DELAY LINES BASED UPON PROPAGATION OF A SURFACE VIBRATIONAL WAVE IN A PIEZOELECTRIC WAVE GUIDE WHICH IS PROVIDED AT ITS EXTREMITIES WITH INTERDIGITATED COMB-SHAPED ELECTRODES. THE DELAY LINE IN ACCORDANCE WITH THE INVENTION COMPRISES AT LEAST ONE COMB STRUCTURE THE TEETH OF WHICH ARE LINKED TO A COMMON CONNECTION BY A SEMICONDUCTOR LAYER WHICH IS RENDERED LOCALLY CONDUCTIVE BY MEANS OF A DISPLACEABLE LIGHT SPOT. THIS TYPE OF LINE CAN BE UTILISED IN A FREQUENCY RANGE EXTENDING FROM ONE MEGACYCLE TO SEVERAL HUNDREDS OF MEGACYCLES, IN ORDER TO PRODUCE DELAYS ADJUSTABLE FROM A FRACTION OF A MICROSECOND TO SEVERAL TENS OF MICROSECONDS.