The invention is directed to different optical active elements (1, 20, 22) such as tunable diffraction gratings and tunable phase shifters having in general a similar setup. The optical active elements (1, 20, 22) comprise an intermediate layer (4) made out of a deformable material which is mechanically interconnected to a driving means. The driving means comprises a first and a second driving plate (2, 3) arranged in general opposite to each other on opposite sides of and at least partially covering the intermediate layer (4) such that a local compression of the intermediate layer (4) by the driving plates (2, 3) causes a local reduction of the thickness in a first direction. This reduction in a first direction causes a secondary deformation of the intermediate layer in a second direction which results in a change of the optical behavior of the optical active element.