Crosslinkable polymer material which may be used in non-linear optics and process for obtaining it

A crosslinked material that is active in non-linear optics, obtained by crosslinking a crosslinkable material that contains a polymer having a chain on which are laterally grafted chromophores that are active in non-linear optics and that may be oriented under the effect of a polarizing electric field, the said chromophores containing an anchoring functional group for stabilizing the orientation of the chromophores by crosslinking after their polarization by an electric field, wherein each chromophore is included in a unit of the polymer which corresponds to the following formula (I):

• ##STR19## in which:
• T is part of the polymer chain,
• A is an --NO.sub.2, --CN or --C(CN).dbd.C(CN).sub.2 group,
• R.sub.1 is a hydrogen atom or a methyl or ethyl group,
• R.sub.2 is a CH.sub.2, C.sub.2 H.sub.4, or C.sub.3 H.sub.6 or C.sub.4 H.sub.8 group, and:
• either X=Y is an azo group, F being a hydrogen atom and G being a group --C(O)--O--W or a group --(O)--O--(CH.sub.2).sub.n --O--W, n being an integer between 2 and 6 and W being a hydrogen atom or a dimerizable group, G then constituting the above-mentioned anchoring functional group or X=Y is an azomethine group, F. being a group --O--W or --R.sub.3 --O--W where W is a hydrogen atom or a dimerizable group, R.sub.3 being a group --O--C(O)--R.sub.4 --or --O--R.sub.4 --where R.sub.4 is a C.sub.1 to C.sub.6 alkyl, and G being a hydrogen atom, F then constituting the said anchoring functional group Or X=Y is an azomethine group, G being a group --O--W or --R.sub.3 --O--W, where W is a hydrogen atom or a dimerizable group, R.sub.3 being a group --O--C(O)--R.sub.4 --or --O--R.sub.4 --, where R.sub.4 is a C.sub.1 to C.sub.6 alkyl, and F being a hydrogen atom, G then constituting the said anchoring functional group, the said polymer additionally containing at least one complementary anchoring functional group capable of attaching itself to the anchoring functional group carried by the chromophore during the crosslinking, said crosslinked material being obtained by crosslinking of said crosslinkable material after polarization of its chromophores by an electric field, the crosslinking being obtained by chemical bonding between the anchoring functional group carried by the chromophore and the complementary anchoring functional group.