Mid-wave infrared beam steering based on high-efficiency liquid crystal diffractive waveplates

We demonstrated two liquid crystal diffractive waveplates: one optimized for nearinfrared (1.06 mu m), and another for mid-wave infrared (MWIR, 3 similar to 5 mu m). By employing a low loss liquid crystal mixture UCF-M3, whose absorption loss is below 2% in the 4 similar to 5 mu m spectral region, the grating achieves over 98% diffraction efficiency in a broad MWIR range. To switch the grating, both active and passive driving methods can be considered. In our experiment, we used a polymer-stabilized twisted nematic cell as the polarization rotator for passive driving. The obtained rise time is 0.2 ms and decay time is 10 ms. (C) 2017 Optical Society of America