A nonlinear optical material is represented by the following formula (1). At least one selected from the group consisting of R.sup.1 to R.sup.5, at least one selected from the group consisting of R.sup.6 to R.sup.10, and at least one selected from the group consisting of R.sup.11 to R.sup.15 are represented by the following formula (2).

##STR00001##

A nonlinear optical material is represented by the following formula (1). At least one selected from the group consisting of R.sup.1 to R.sup.5, at least one selected from the group consisting of R.sup.6 to R.sup.10, and at least one selected from the group consisting of R.sup.11 to R.sup.15 are represented by the following formula (2).

##STR00001##

The invention concerns a nanostructured layer system comprising a substrate, an intermediate layer, which comprises an aromatic azo compound, applied to the substrate, and a metallic cover layer applied thereto, whereby the intermediate layer is structured in a light-induced manner by irradiation of light.

The nanostructured layer system is characterized in that the metallic cover layer contains nickel as a ferromagnetic metal and that the light is linearly polarized for structuring.

The invention further concerns a method for producing such a nanostructured layer system.

The invention concerns a nanostructured layer system comprising a substrate, an intermediate layer, which comprises an aromatic azo compound, applied to the substrate, and a metallic cover layer applied thereto, whereby the intermediate layer is structured in a light-induced manner by irradiation of light.

The nanostructured layer system is characterized in that the metallic cover layer contains nickel as a ferromagnetic metal and that the light is linearly polarized for structuring.

The invention further concerns a method for producing such a nanostructured layer system.

In the specification and drawings, a collinear holographic storage medium is described and shown with a recording layer, wherein the lateral linear thermal expansion coefficient of the recording layer is substantially the same as the linear thermal expansion coefficient of the material of the recording layer.

In the specification and drawings, a collinear holographic storage medium is described and shown with a recording layer, wherein the lateral linear thermal expansion coefficient of the recording layer is substantially the same as the linear thermal expansion coefficient of the material of the recording layer.