BACKGROUND ART As known, a logical port is a device capable of switching into one or more physical statuses based on an external pulse , which for simplicity of the discussion we shall call gate signal, or simply gate.

Moreover, it is known that it is possible to change the refractive index of molecules exhibiting a non-linear optical activity.

The variation of the refractive index perturbs the path of another light pulsing beam co with wavelength X, such that O X 'and X More in particular, the variation of the refractive index can be obtained using the Pockels effect, the Kerr effect and the effect of optical bi-refraction on molecules exhibiting a non-linear optical activity (NLO) of the second and third order.

Typically, the NLO activity appears as a polarisation,

induced by the electrical field of the incident light, characterised at the material level by the constants #(2)#jk (- co, co, 0) and #(3)#jk1 (-#, #, 0, 0) and at the molecular level by the constants ßijk(#), γijk (#) and 8a (#) = αzz (#) - 1/2 (aXx (#) + αγγ (#)).

As known, y, (2) is second order polarisation, X (3) iS third order polarisation, a is first order molecular polarisation, ß is second order molecular polarisation and y is third order molecular polarisation.

As known, the Pockels, Kerr and optical bi-refraction effects occur if the NLO molecules are immersed in an electrical field such as, for example, that generated in a Mach-Zender device, rather than by a separation of charges photo- generated in a photo-refractive material.

From the discussion above it is evident that in order to obtain effects changing the refractive index it is necessary to introduce the molecules in an electric field, for example in a Mach-Zender device, or in any case to set up complex operating conditions to obtain the generation of the electric field.

SUMMARY OF THE INVENTION Therefore, object of the present invention is that of solving the problems mentioned above by realising a logical optical device which should work without requiring further elements for the generation of the electric field.

Another object of the present invention is that of realising a logical optical device which should be connected in series to other similar optical devices.

A further object of the present invention is that of realising a logical optical device which should be connected to other similar optical devices to form logical ports or complex logical circuits.

A further object of the present invention is that of realising a logical optical device which should be connected to other similar optical devices to form substantially planar and multilayer configurations.

Such objects are achieved, according to the present invention, by a logical optical device, according to claim 1, to which reference shall be made for shortness.

Further features of the invention are illustrated in the dependent claims.

The claimed invention also comprises a procedure for generating a logical optical signal.

The invention is described in more detail hereinafter, by way of a non-limiting example, with reference to the attached drawings.

DESCRIPTION OF THE DRAWINGS In such drawings: Figure 1 is a schematic view of an exemplificative embodiment of the logical optical device according to the

present invention; - Figure 2 is a schematic view illustrating the operation of the present invention; - Figure 3 is a schematic view of another preferred embodiment of the invention; - Figure 4 is a schematic view of yet another preferred embodiment of the invention; -Figure 5 shows an example of molecule intended to generate the electric field according to the teachings of the invention; - Figure 6 shows an example of molecule exhibiting a non- linear optical effect, an effect to be used according to the teachings of the invention; Figure 7 shows a molecular example of the invention according to the diagram of Figure 1; - Figure 8 shows the molecule of Figure 6, in an excited state; and - Figure 9 shows the molecule of Figure 7 in an excited state.

DETAILED DESCRIPTION OF THE INVENTION With initial reference to Figure 1, the logical optical device is globally indicated with reference numeral 10.

Device 10 consists of two molecules intended to generate the electric field (CG), indicated with reference numeral 11, where the above molecules 11 are connected in series to a

third molecule provided with non-linear optical properties (NLO), in turn indicated with reference numeral 12.

The molecules intended to generate the electric field are characterised in that they exhibit a separate-charge orbital representation of the excited state or fundamental status.

In such logical optical device 10, the electric field is generated by the separation of charges produced or annulled by the passage to the excited state (HOMO? LUMO), caused by the absorption of the gate, in molecules connected in an ordered manner with the NLO molecule, as in Figure 1.

By way of a non-exhaustive exemplification of the inventive concepts expressed herein, let's now consider Figure 5, which illustrates an example of molecule intended to generate the electric field (CG).

On the other hand, Figure 6 illustrates an example of molecule exhibiting a non-linear optical effect (NLO), whereas Figure 7 illustrates a molecular example of the invention according to the diagram of Figure 1.

To better understand the operation of the invention, reference shall now be made to Figure 2.

In the present invention, the gate consists of a light pulsing beam'and consequent wavelength XI.

The variation of the refractive index perturbs the path of another light pulsing beam w and consequent wavelength X, such that # # #' and # # #'.

This other light beam, where the device suitably inserted in the proper configuration, such as for example the typical configuration of a Mach-Zender, acts as signal.

It should also be noted that the device of the invention can work as a logical port NOT, without for this reason limiting the invention described for this use.

This means that more similar devices can be combined, according to the Boole algebraic rules, to form different logical ports, as well as more complex circuits.

Of course, as the signal (radiation) must not be absorbed by molecule CG and by molecule NLO, in the same way the gate (radiation') must only be absorbed by molecule CG.

To exemplify the present invention at a molecular level, Figure 8 illustrates the molecule of Figure 6 in an excited state, and Figure 9 illustrates the molecule of Figure 7, that is the logical optical port 10, in an excited state.

Nothing prevents the use of different molecules NLO, different molecules CG, as well as different orders in the connection of the molecules and different radiations according to their function for the purposes of the present invention.

For this reason, the materials with which the system is realised can be different but it must meet the four requirements identified above.

By way of an example of the multiple and considerable

possibilities offered by this finding, some variants of the invention are reported below.

The ordered system, as represented in Figure 1, can be dispersed or anchored to a polymer transparent to radiations O and'.

The different molecules can be differently connected in order to obtain a polymer consisting of the same molecules, as shown in Figure 3.

The different molecules can be anchored to a surface and form a SAM (Self Assembling Multilayers), as shown in Figure 4.

The inventive concepts described also allow the definition of a procedure for generating a logical optical signal.

The procedure at least comprises the step of connecting two molecules intended to generate the electric field to a third molecule provided with non-linear optical properties, and the step of using a first light beam as optical gate signal for generating such electric field as to change the optical properties of the above third molecule with non-linear optics, so as to perturb the path of a second light beam acting as logical signal.

The present invention can be subject to several modifications and variants, all falling within the inventive concept expressed in the attached claims, whereas the technical details can change according to the requirements.

In particular, in the above discussion reference is made to a

separate charge form in the excited state, but it should be noted that the system is absolutely valid also with systems with an inverted behaviour; in fact, what is more important is the variation between the two physical statuses rather than the absolute status.