X-ray Generation from Optical Transparent Materials by Focusing Ultrashort Laser Pulses

In this chapter, studies on interactions of intense laser fields with transparent materials such as glasses, polymer targets, and solutions are reviewed from the viewpoint of the high-energy photon emission of EUV, soft X-rays, and hard X-rays. Fundamentals of the mechanisms leading to high-energy photon emission are summarized on the basis of experimental results, like X-ray emission spectra. Experimental setups for laser-induced hard X-ray emission from solutions and solids are provided and the effects of air plasma formation and sample self-absorption of X-rays on X-ray generation are described. Photo-ionization processes of transparent materials and effects of the addition of electrolytes are also considered. The effects of multi-shot and double-pulse irradiation of laser pulses on X-ray emission from solid materials and solutions are explained. Finally, some possible applications using X-rays from transparent materials are suggested.