Mechanically Tunable Bilayer Composite Grating for Unique Light Manipulation and Information Storage

Abstract Composite gratings play important roles in modern information technology. However, such gratings are generally based on the same structural pattern with limited types, and their structural parameters are difficult to tune, which greatly limit their application. A mechanically tunable composite grating in bilayer film, which orthogonally couples a sinusoidal phase grating and a rectangular phase grating, is developed here. The structural parameters of the grating can be well tuned by mechanically stretching or releasing the grating in the uniaxial direction. Naturally, this property allows tunable light manipulation: that is, a single incident laser beam can be split into a 2D diffraction beams array, and the intensity and propagation angle of each diffraction beam can be precisely controlled via mechanical manipulation of the grating. A theoretical model based on scalar diffraction theory that can quantitatively describe and accurately predict this light manipulation is further established. In addition, after treatment with an electron beam, the tunable structures can be immobilized, which enables the storage of information in the bilayer film. This work may open up new pathways for composite grating fabrication and further extend the applications of composite gratings in diverse fields.