Assessment of light diffraction and focusing of chirped gratings by the beam propagation method

摘要

In this paper, we investigate the competence of the Fast Fourier Transform based beam propagation method (FFT-BPM) in the analysis of the diffraction of a Gaussian light beam by linearly binary chirped gratings. The visibility and the focusing of the diffraction orders are investigated thoroughly. The waist size and focal distance of the diffraction orders are extracted easily. Moreover, the key parameters that control the Gaussian beam deflection and focusing are examined for more improvement of the chirped grating lens operation and to design a beam splitter. The applicability and accuracy of the method is verified by comparing our results with those obtained by other analytical method. The comparison showed a good agreement. Furthermore, the illumination by flat-top beam profiles such as rectangular and super-gaussian are studied.