With a view to making highly efficient light shutters, the object of this study is to know the best structure of the liquid crystal polymer composite yielding a high extinction ratio. The main feature of this letter shows that experimental results are consistent with anomalous diffraction approach. For our demonstration, we made polymer dispersed liquid crystal (PDLC) cells having different droplet radius (a), ranging from 0.5 to 1 μm. In addition, a strong wavelength sensitivity with these radii is measured in the visible region. Beyond one micron, droplets yield higher transmission as regards both the wavelength and the optical anisotropy of the liquid crystal. These results bring forward that the most efficient PDLC films must follow the optimization relation: a(Δn)/λ=0.3, where λ is the wavelength and Δn the liquid crystal anisotropy. © 1996 American Institute of Physics.