Behavior of disclination arrays across the nematic-smectic transition*

Versatile control over liquid crystal alignment is key to the development of novel electro-optical devices. We use photo-alignment to create topological defects in nematic liquid crystals. The preferred alignment direction of the nematic director at parallel glass substrates is set using a surface layer of azo-dye that undergoes photo-reorientation upon exposure to blue light. Our projector-based optical system can pattern molecular orientations at two independently controlled confining surfaces. Altering the projected pattern and the system geometry allows us to produce topological defects arrays of both half-integer and integer disclinations. This capability to precisely synthesize 3D disclination networks offers a promising step in constructing and manipulating mechanical and optical metamaterials. We observe and discuss the behavior of disclination networks across the nematic-smectic phase transition.