Stable polarization gratings recorded in azo-dye-doped liquid crystals

We report on the design, fabrication, electro-optical performance, and stability of switchable polarization gratings formed in azo-dye-doped nematic liquid crystals. Stable gratings are demonstrated even after applying saturating electric fields ( 8 V ∕ μ m ) and after heating to extreme temperatures ( T = 190 ° C ) . A simple phenomenological model is presented to show that the Freedericksz threshold voltage depends on surface and volume contributions. The observed thresholdless behavior indicates that the grating stability is consistent with a surface-stabilizing effect.