Abstract

Intense ultrashort optical lasers can be used to generate x rays that can photo-ionize inner-shell electrons in a range of elements. For a sufficiently intense and short pulse of x rays, lasing can occur in the filling of the inner-shell hole [1]. In these x-ray laser schemes, the very fast Auger decay of the upper laser level requires a very intense source of x-rays and the filling of the lower laser level requires a very fast rise time for the x rays. Inner-shell schemes are of particular interest because of their potential for lasing at short wavelengths. Collisional x-ray laser schemes using Ni-like ions have demonstrated lasing down to 35 Å (Ni-like Au) but cannot be extended below 20 Å (Ni-like U) [2]. Photoionization of the K-shell offers the possibility of x-ray lasing in the wavelength range from 15 down to 5 Å for elements from Ne to K.

© 1993 Optical Society of America