Laser Physics
The Kapteyn/Murnane group, with Visiting Fellow Charles Durfee, has figured out how to use visible lasers to control x-ray light! The new method not only preserves the beautiful coherence of laser light, but also makes an array of perfect x-ray laser beams with controlled direction and polarization. Such pulses may soon be used for observing chemical reactions or investigating the electronic motions inside atoms. They are also well suited for studying magnetic materials and chiral molecules like proteins or DNA that come in left- and right-handed versions.
For decades after the invention of the red ruby laser in 1960, bright laser-like beams were confined to the infrared, visible, and ultraviolet region of the spectrum. Today there鈥檚 an exciting revolution afoot: new coherent x-ray beams are now practical, including the EUV beams gracing the cover of the May 1, 2015, special issue of Science honoring the International Year of Light. The same issue features an article entitled 鈥淏eyond Crystallography: Diffractive Imaging Using Coherent X-ray Light Sources鈥 that celebrates the revolutionary advances in both large- and small-scale coherent x-ray sources that are transforming imaging in the 21st century.
Mid-infrared (mid-IR) laser light is accomplishing some remarkable things at JILA. This relatively long-wavelength light (2鈥4 碌m), when used to drive a process called high-harmonic generation, can produce bright beams of soft x-rays with all their punch packed into isolated ultrashort bursts. And, all this takes place in a tabletop-size apparatus. The soft x-rays bursts have pulse durations measured in tens to hundreds of attoseconds (10-18聽s).