The invention relates to a method for producing a slotted guide, in which: a) a layer of a material having a refractive index less than that of silicon, for example Material having a refractive index less than that of silicon (26), is formed on an etching barrier layer (22), b) two parallel trenches are etched into said material having a refractive index less than that of silicon, with the etching barrier on said etching barrier layer, these two trenches being separated by a wall of said material having a refractive index less than that of silicon (36), c) the trenches thus made are filled with silicon (42, 44).