X-ray lasers pumped by ultra-short light pulses

Short pulsed lasers have become a popular means to drive X-ray lasers. A number of different schemes have been demonstrated by which population inversion, and hence gain, may be achieved. The compactness and relatively high repetition rate of such pump lasers may make them a potential source for table-top' operation. This paper will survey a number of approaches, using optical field ionisation (OFI) to pump both collisional and recombination soft X-ray lasers. We examine some of the underlying features of OFI lasers and assess their potential as future small-scale laboratory systems.