The Fourier-Mukai transform comes from a bimodule: the Poincaré bundle. Let A$A$ be an abelian variety, the Poincaré bundle P$\mathcal{P}$ is a vector bundle on AxÂ$A \times \hat{A}$ coming from the fact that the points in the dual abelian variety Â$\hat{A}$ parametrize line bundles on A$A$ (P$\mathcal{P}$ is the universal family). In the Fourier-Mukai construction, P$\mathcal{P}$ is used as a OA$\mathcal{O}_A$-OÂ$\mathcal{O}_{\hat{A}}$-bimodule to produce a functor between the derived categories of coherent sheaves on A$A$ and Â$\hat{A}$ via a push-pull construction.