Low scattering and polarization-independent polymer/liquid crystal grating

In order to get low scattering and polarization-independent holographic polymer dispersed liquid crystal（HPDLC)grating, low functionality acrylate monomers were adopted and the fabricating temperature was increased gradually. First, two kinds of acrylate monomers were selected, one was pentafunctional dipentaerythritol hydroxyl pentaacrylate (DPHPA) , the other was difunctional phthalic diglycol diacrylate (PDDA). Besides N-vinylpyrrolidone (NVP) which served as solvent and chain extender was adopted. Then, the effects of fabricating temperature on the HPDLC grating was investigated, and it is found that the highly anisotropic grating fabricated at room temperature becomes polarization-independent by its clearing point（62 ℃）. Also a more complete phase separation of liquid crystal from polymer is demonstrated. Besides, optical measurement carried at the Bragg angle shows a 66.7% scattering loss decrease, this result is further conformed by scanning electron microscopy (SEM) analyses. And also this hightemperature fabricated grating shows a polarization independent behavior.