Defect-free switchable phase grating

Liquid-crystal-filled polymer structure devices offer a very low cost switchable spatial phase modulator. The phase profile set by the polymer structure may be varied or switched on/off with an applied field. Defects have been observed in some devices giving rise to spurious diffraction peaks. Computational modeling of the liquid-crystal director profile suggests that these defects might be suppressed if the dimensions of the liquid-crystal region are small. Experimental measurements confirm that this approach is effective in controlling the defects. This provides a route to fabrication of low-cost switchable complex diffractive devices.