Flexible diffractive gratings: theoretical investigation of the dependency of diffraction efficiency on mechanical deformation

The mechanical deformations of variable elastomeric diffractive optical elements are calculated by finite element methods. Starting from optimized blazed gratings, the derived profile variations serve as an input for rigorous-coupled-wave analysis to calculate the diffraction efficiency of a spectral band from 200 to 1200 nm. Applied planar strain of up to 80% has little effect on the maximum diffraction efficiency for large grating-period-to-wavelength ratios, g/λ, with only a shift toward shorter wavelengths. With a decreasing g/λ, the maximum efficiency also decreases when stretching the grating structure. Further influences of profile design like the angle of the antiblaze facet and the use of higher-order blaze profiles were investigated. Finally, we simulate the change in the diffraction efficiency at a single wavelength of a flexible blazed grating in direct contact with a rigid glass plate. In this case, the soft matter grating is compressed and deformed to reduce the diffracting properties.