Here is an application that utilizes the impressive diffractive properties of Polarization Gratings (PGs). The figure shows the operating principle behind a transmissive light shutter that uses PGs with a liquid crystal cell to act as a very efficienct light switch, approaching ~90% total transmittance in the bright state. In the ON state, almost all the light is unaffected. In the OFF state, the LC cell switches the polarization states such that the PGs diffract all the light away causing a dark state.
Approaches like this have been utilized for other applications including LCDs, beam steering, tunable color filters, etc.