  We report on the use of elliptical pump spatial modes to increase the
observed brightness of spontaneous parametric downconversion in critically
phase matched crystals. Simulations qualitatively predict this improvement
which depends on the eccentricity and orientation of the pump ellipse. We
experimentally confirm a factor of two improvement in brightness when compared
to the traditional circular-symmetric pump spatial modes. These results support
previous theoretical work that proposes the use of elliptical pump modes to
enhance the performance of parametric processes in anisotropic materials.
