Examples of OAGs
An example of a transverse OAG, the so-called cycloidal OAG, is shown in Fig. 1. The optical axis in this grating is monotonously modulated in transverse direction. This grating is capable of diffracting all incident light into either +1st or −1st order in a micrometer-thick layer . The cycloidal OAGs have already been proven to be very efficient in beam steering and optical switching.
In another type of OAG, the optical axis is modulated in the direction of light propagation (Fig. 2) with a modulation period equal to a fraction of the wavelength (200-3000 nm). This modulation prevents these frequencies from propagating within the grating, acting as a band-stop filter. As a result, any light with frequency within the matching range will be reflected from the OAG. However, unlike cholesterics which reflect only one of two circular polarizations of incident light, this OAG reflects any polarization.
Read more about this topic: Optical Axis Grating
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