X-ray pumped laser produces 1.4 A narrow-linewidth hard x-ray emission
In 2011, Japanese researchers achieved coherent x-ray free-electron laser emission of 1.2 Å from the SPring-8 Angstrom Compact Free Electron Laser (SACLA; Hyogo, Japan), which today routinely produces < 1 Å hard x-ray pulses (photon energy on the order of 10 keV) with 1020 W/cm2 maximum focus intensity.
Now, in an effort to further the study of the movement of electrons within materials and, hence, gain crucial light-matter interaction information that governs nearly all physical processes, researchers at the University of Electro-Communications and the University of Tokyo (both in Tokyo, Japan), RIKEN and JASRI (Hyogo, Japan), and Osaka and Kyoto University have developed a 1.4 Å (0.14 nm) hard x-ray laser from a copper target with an inner-shell electron excitation scheme. By using a two-color pulse from the SACLA system, they successfully seeded the hard x-ray laser to maximize temporal coherence at almost ideal limits. The narrowest bandwidth obtained is 1.7 eV—smaller than the natural width defined by the lifetime of the atomic transition because of the uncertainty principle. The narrower linewidth denotes the effective decay time of 1 s in artificially suppressed vacancy ions. In this SACLA-seeded laser, strong induced emission occurs and the branching ratio of the relaxation process of the K-shell vacancy (Kα1, Kα2, and Auger process) is changed from its nominally constant values. This allows pure Kα1 or Kα2 laser emission with high efficiency. Reference: H. Yoneda et al., Nature, 524, 446–449 (Aug. 27, 2015).
Gail Overton | Senior Editor (2004-2020)
Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.