Dual-function beam shapers fabricated by photoaligned liquid crystal cells

A dual-function beam shaper is composed of a photoaligned liquid crystal (LC) cell and two polarizers. The photoaligned LC cell is formed by irradiating an intensity-gradient pump beam on each of the two surfaces of a dye-doped LC cell. The LC directors on the irradiated surfaces gradually transit from a homogeneous orientation to a mutually orthogonal homogeneous one. The LC cell under crossed (parallel) polarizers exhibits a lower (higher) transmittance in the center of the director-continuously-rotating region than at the edges of the region. The cell acts as a beam shaper with the function of a beam flattop (compression).