684349.fig.038
Figure 38: Diffraction efficiency versus the electric field curves for Bragg gratings made of liquid crystal E7 with three different kinds of surfactants, octanoic acid (no. 1), S-271 POE sorbitan monooleate (no. 2), and Tergital Min-Foam 1X (no. 3), respectively. The diffraction efficiency without surfactant is also shown for comparison.