RESUMO
Chiral media interact preferentially with either left- or right-circularly polarized electromagnetic waves, leading to effects including circular dichroism, optical rotation and circular preferential scattering. In this experiment, we revisit Lindman's famous 1920 experiment linking artificial chiral materials to optical activity and we record the first time-domain measurements of a single-cycle THz pulse transmitted through randomly oriented metallic helices. Time-resolved measurements of co- and cross-polarized components of the transmitted electric field allow the electric field trajectory to be reconstructed and time dynamics of the two circular components to be investigated. For the first time, we show that time dynamics reveal two distinct effects that are separated in time: local preferential circular scattering and collective coupling. These findings are important on furthering our understanding on the analogy between optical activity arising from light interaction with large chiral molecules and that from macroscopic artificial chiral media.
Assuntos
Nefelometria e Turbidimetria/métodos , Refratometria/métodos , Espectroscopia Terahertz/métodos , História do Século XX , Luz , Nefelometria e Turbidimetria/história , Refratometria/história , Espalhamento de Radiação , Radiação Terahertz , Espectroscopia Terahertz/históriaRESUMO
A talented young scientist, Thomas Harriot, wrote the first English account of the New World, "A Briefe and True Report of the New Found Land of Virginia," distinguished by its serious effort to describe and understand the American Indian. Harriot went on to make innovations in mathematics and was one of the first astronomers to use the telescope. His largely unappreciated contribution to the history of ophthalmology was the first formulation of the sine law of refraction of light, found in his unpublished papers long after his death in 1621. Willebrord Snell discovered the sine law in Holland in 1621 but also died without formally publishing it. Rene Descartes first published the sine law in 1637. The sine law of refraction became not only the prime law of all lens systems but ushered in a new world of physical laws.