Far-field diffraction of linear chirped gratings

Abstract

We analyze the far-field diffraction pattern produced by linear spatial chirped gratings. An intuitive analytical interpretation of the generated diffraction orders is proposed for gratings with linear variation of the period and linear variation of the spatial frequency. Also, experiments using Gaussian beams and plane wave illumination are performed. The analytical expressions are compared to numerical and experimental results, showing a high agreement. Chirped gratings can be implemented in interesting applications: we analyze how they can be used as a deflector, since tunable direction of diffracted orders can be achieved by displacing laterally the grating with respect to the incident light beam. Also the angular width of diffraction orders can be controlled and chirped gratings can be used to generate uniform illumination over a controlled angular range. These two applications have also been experimentally shown.