Lasing of infrared free-election lasers using the storage ring NIJI-IV.

We report for the first time to our knowledge the experimental achievement of a storage ring free-electron laser (FEL) device dedicated to applications in the IR region. IR FELs were oscillated in the wavelength region of 1392-1502 nm, and the relative linewidth was 3 x 10(-4). The maximum power of the IR FEL transmitted through a vacuum window was approximately 0.3 mW, and the intracavity power was approximately 2 W. We have already observed an intensive quasi-monochromatic x ray by using FEL Compton backscattering. The results of our study are expected to lead to applications in which an IR FEL and a quasi-monochromatic x ray will be used simultaneously.