| Summary: | Nonlinear photonic crystals: controlling light from any which way A three-dimensional nonlinear photonic crystal that manipulates light incident from any direction could allow new types of beam shaping for optoelectronic devices. In certain crystals, atoms arrange in mesoscopic structures called supercells, which cause light to interfere in useful ways. Generally, such crystals can only affect light beams that are incident from particular directions, and with certain polarizations. Now, Haohai Yu at Shandong University in Jinan, China, and co-workers have grown crystals of potassium tantalate niobate, with the constituent atoms in a critical ratio that provides a Rubik’s-cube-like structure with supercells 3–10 µm in size. The researchers observed rotating ferroelectric polarization and second harmonic generation in laser beams incident from all three dimensions (x, y, and z directions). They hope that the crystal could provide a useful platform for applications such as terahertz radiation and holography.
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