We study tunable refraction of light in one-dimensional periodic lattices induced optically in a photorefractive crystal. We observe experimentally both positive and negative refraction of beams that selectively excite the first or second spectral bands of the periodic lattice, and we demonstrate tunability of the output beam position by dynamically adjusting the lattice depth. At higher laser ...

Surprisingly colourful views are possible from sparkling white snow. It is well known that similarly colourful features can exist in the sky whenever appropriate ice crystals are around. However, the transition of light reflection and refraction from ice crystals in the air to reflection and refraction from those in snow on the ground is not trivial. Photographs and videos from brilliant colour...

Electro-optic switching of reflection and refraction is experimentally demonstrated in metasurface liquid crystal cell. Negative metasurface is fabricated by focused-ion-beam milling, and twisted nematic cells are constructed with complementary double-split ring resonator and V-shape slot antenna metasurface. By application of an external voltage, electro-optic switchings are achieved in reflec...

We present a novel type of three-dimensional dark focus optical trapping potential for ultracold atoms and Bose-Einstein condensates. This ‘optical bottle’ is created with blue-detuned laser light exploiting the phenomenon of conical refraction occurring in biaxial crystals. We present experiments on confining a Rb Bose-Einstein condensate in this potential and derive the trapping frequencies a...

Light-absorbing materials are widely used, and their optical properties an important factor. Snell's law does not hold in that partially absorb light. Hence, the path refraction is calculated from Maxwell's law. We used to obtain deviation angle when a light passes through prism made of light-absorbing material. The has local maximum. near maximum sensitive real imaginary parts refractive index...