VOLUME GRATING PRODUCED BY INTERSECTING GAUSSIAN BEAMS IN AN ABSORBING MEDIUM - A BRAGG DIFFRACTION MODEL

摘要

Theoretical and experimental results are reported on the diffraction of a Gaussian probe beam by a volume grating formed by two intersecting Gaussian pump beams in an absorbing medium. The analysis is carried out considering pure phase gratings. The efficiency dependence on the sample thickness, absorption, and the crossing angle are discussed. The results show that the spatial profile of the diffracted beam has an elliptic Gaussian profile if the ratio of the sample thickness to the overlap length of the two intersecting Gaussian beams is greater than or equal to 0.16. The spatial profile of the diffracted beam is also dependent on the absorption coefficients of the interacting beams. We find that the optimum probe-beam spot size is always smaller than the spot size of the write-beam and is dependent an the sample thickness. [References: 22]