Security element for producing valuable documents such as banknotes or cheques, comprising: - a dielectric substrate (7, 8), - a first structure lying in a first plane and having a polarization effect in transmission observation, - a second structure lying in a second plane, which is spaced apart from the first plane, and having a further or the same polarization effect in transmission observation, and - a material which is transparent in the visible spectral range, is arranged between the first and second structures (2, 4) and is formed such that it modifies polarized light transmitted by one of the two structures (2, 4) in such a way that it impinges in depolarized or circularly polarized fashion on the other of the two structures (4, 2), characterized in that - the first structure is formed as a first line grating structure, which is periodic with a period of not more than 450 nm in a first spatial direction and comprises grating webs embedded in the substrate and separated from one another in each case by grating gaps formed from the surrounding substrate, and - the second structure is formed as a second line grating structure, which is periodic with a period of not more than 450 nm in a second spatial direction and comprises grating webs embedded in the substrate and separated by grating gaps formed from the surrounding substrate, - wherein each line grating structure (2, 4) is designed to produce a polarization effect manifested as wavelength-dependent polarization filtering, wherein the wavelength dependence produces a colour filtering of polarized illumination which is dependent on the orientation of the line grating structure. - a dielectric substrate (7, 8), - a first structure lying in a first plane and having a polarization effect in transmission observation, - a second structure lying in a second plane, which is spaced apart from the first plane, and having a further or the same polarization effect in transmission observation, and - a material which is transparent in the visible spectral range, is arranged between the first and second structures (2, 4) and is formed such that it modifies polarized light transmitted by one of the two structures (2, 4) in such a way that it impinges in depolarized or circularly polarized fashion on the other of the two structures (4, 2), characterized in that - the first structure is formed as a first line grating structure, which is periodic with a period of not more than 450 nm in a first spatial direction and comprises grating webs embedded in the substrate and separated from one another in each case by grating gaps formed from the surrounding substrate, and - the second structure is formed as a second line grating structure, which is periodic with a period of not more than 450 nm in a second spatial direction and comprises grating webs embedded in the substrate and separated by grating gaps formed from the surrounding substrate, - wherein each line grating structure (2, 4) is designed to produce a polarization effect manifested as wavelength-dependent polarization filtering, wherein the wavelength dependence produces a colour filtering of polarized illumination which is dependent on the orientation of the line grating structure.