High resolution amplitude and phase gratings in atom optics
  An atom-field geometry is chosen in which an atomic beam traverses a field interaction zone consisting of three fields, one having frequency $\Omega =c/\lambda $ propagating in the $\hat{z}$ direction and the other two having frequencies $\Omega +\delta_{1}$ and $\Omega +\delta_{2}$ propagating in the -$\hat{z}$ direction. For $n_{1}\delta_{1}+n_{2}\delta_{2}=0$ and $|\delta_{1}| T,|\delta_{2}| T\gg 1$, where $n_{1}$ and $n_{2}$ are positive integers and $T$ is the pulse duration in the atomic rest frame, the atom-field interaction results in the creation of atom amplitude and phase gratings having period $% \lambda /[2(n_{1}+n_{2})]$. In this manner, one can use optical fields having wavelength $\lambda $ to produce atom gratings having periodicity much less than $\lambda $. 
P. R. Berman, B. Dubetsky, and J. L. Cohen (University of Michigan)