Electrically/optically tunable photo-aligned hybrid nematic liquid crystal Dammann grating.

In this Letter, we disclose a Dammann grating (DG) based on the hybrid photo-aligned nematic liquid crystals (LCs). The LC cell is composed of two substrates, wherein the first substrate is treated to provide the homeotropic alignment, and the other substrate is set to provide an in-plane, patterned alignment with a mutually orthogonal easy axis in the neighboring alignment domains. Thus, the fabricated polarization independent DG generates an optical array of equally distributed energy, which is characterized by a diffraction efficiency of more than 58%, a response time <1  ms, and the driving voltage 3 V/μm. Furthermore, the optically active alignment layer provides the optical tunability and reconfigurability for the proposed DG. With these advantageous parameters, these DGs can be applied in modern applications.