Manufacturing process for a electro-optical tunable filter according to any of the previous claims characterised by the fact that the optical waveguide on a support of borosilicate glass is obtained through the technique of double ion-exchange, that a first ion-exchange K+/Na+, with a glass support immersed in a first saline bath of potassium nitrate, is carried out at a temperature of between 380° C. and 450° C. for a time of between 60 and 90 minutes, that a mask of metal, preferably aluminium, is deposited by vacuum evaporation on the glass support and defined photolithographically for the determination of the optical waveguide with a channel, that a second exchange Ag+/Na+with the immersion of the glass support in a second saline bath constituted of a mixture of sodium nitrate and silver nitrate is carried out at a temperature of between 320° C. and 350° C. for a time of between 4.5 and 6 hours, that a second photolithographic process is carried out and then a subsequent etching of the metal that is partially removed in such a way as to leave coplanar electrodes for the application of the voltage, that a covering glass is glued to the support containing the optical waveguide, that suitable spacers are used in such a way as to obtain a gap of a few microns, that the gap is filled with a mixture of liquid crystal and pre-polymer for the creation of the grating, that the mixture of liquid crystal and pre-polymer is exposed to a figure of interference, for a suitable period, between two laser strips of a wavelength suitable to bring about the polymerisation of the pre-polymer.