The principles of laser beam control with polarization gratings introduced as diffractive waveplates

摘要

The development history of polarization gratings (PGs), with origins in holography and Bragg gratings, accentuated and reinforced their perception as gratings. We highlight their nature as waveplates - diffractive waveplates (DWs) - and stress their family connection to vector vortex waveplates. This approach provides a straightforward understanding of the unusual properties of PGs, such as nearly 100% diffraction in thin material layers, the presence of only one diffraction order for a circularly polarized beam, wide diffraction bandwidth and the possibility of achromatic behavior. With technology being ripe for applications such as beam steering, and optical switching, we characterize the resistance of DWs to optical radiation, the effects of temperature and deformations. We also show that the boundary effects in the manufacturing process make it necessary to use substrates larger than the desired aperture of the DW. The multi-component systems are discussed for developing normally transmissive switchable imaging systems, beam scanning, and achromatic diffraction.