Credit: Image courtesy of Dan Hickstein and Steven Burrows, JILA
Counter-rotating circularly polarized laser beams (red) are crossed in a gas target to generate angularly separated extreme ultraviolet (EUV) harmonics with right- and left-circular polarization (blue, purple, magenta). This method provides straightforward and robust control of the direction, polarization, and spectrum of the light, opening the door to investigating materials in ways that were never before possible.