He et al., "High contrast switching of distributed-feedback lasing in dye-doped H-PDLC transmission grating structures," Optics Express, vol.
Holographic polymer dispersed liquid crystals are known as H-PDLCs. They are made by holographic recording in a photopolymerization induced phase separation process (PIPS) in which the liquid crystal molecules diffuse to dark zones in the diffraction grating where they can be oriented by means of an electric field.
Figure 3 shows the transmission spectrum before recording H-PDLC layer containing YEt dye.
H-PDLC materials contain mainly polyfunctional monomers in order to get an effective PIPS effect.
But this photopolymer is a H-PDLC material, and thus we obtain better results with low dye concentrations around 0.1% due to the polyfunctional monomer.
NPG is a standard initiator used in H-PDLC materials.
It is a critical component in improving acrylate-based H-PDLC materials by reducing the liquid crystal droplet size.
Additionally, OA acts as a surfactant decreasing the driving voltage improving the electrooptical dynamics of the H-PDLC device.
The H-PDLC devices with the compositions shown in Table 2 are used as holographic media for the recording of unslanted diffraction gratings.