‘Cartwheeling’ light reveals new type of polarized light-matter interaction

Technologies that rely on interactions between matter and polarized light usually stick to the well-understood effects of linear or circular polarization. Researchers at Rice University in the US have now opened the door to fresh approaches by studying how matter reacts to an additional form of polarization. This form, known as “trochoidal” polarization, is characterized by a “cartwheeling” motion in light’s electric field that can occur in either a clockwise or anticlockwise direction. Since matter can distinguish between these two directions, trochoidal dichroism could be used to develop novel spectroscopic tools.