Modifying light propagation in planar waveguides with cladding liquid crystals

Liquid crystal devices are increasingly being used in non-display applications to manufacture small devices that can be driven by low voltage electronics. LCs are low cost, light weight and avoid using mechanical components. A wide number of interesting applications involve the use of LCs for phase modulation of light. This can be done with light propagating through the LC itself or rather with light propagating in a waveguide (WG) where sections of its cladding are filled with LC that interacts with the light?s evanescent field. Several device families based on this general outline are being tested in our group. The devices can be roughly classified into two categories. The first group consists of WGs having a width much larger than the light wavelength (Fig. 1), therefore behaving as 1D waveguides. In these structures, effective beam steering can be achieved using pixelated electrodes having specific shapes. Beam steering has been demonstrated in IR beams [1] using silicon substrates. In our laboratory, steering of visible light is tested employing, besides silicon substrates, ITO-coated glass substrates with a high-index guiding layer of SU-8.