Ultrahigh peak power vacuum ultraviolet laser and its applications

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(1) We have demonstrated vacuum ultraviolet emissions from pulsed rare gas jet excited by a high intensity ultrashort pulse laser. Various characteristics of the high intensity laser produced plasma such as electron density and temperature are evaluated. Intensity of the vacuum ultraviolet emission is larger than that of high-order harmonic signals observed simultaneously. This result indicates that the excimer emission initiated high intensity laser produced electons is strong enough to be utilized for practical applications. These knowledge should be used to develop a practical short pulase laser in the laboratory scale.(2) A theoretical model describing the amplification of an ultrashort pulse vacuum ultraviolet light has been developed. This model was verified to compare the results to well known rare gas halide excimer laser amplification.(3) The control of a molecule by using a high intensity laser has been demonstrated in the femtosecond time region as well. Alkali halide molecu … More les have been excited and deexcited by using two different wavelength (ultraviolet and visible) lasers, which leads to the coherent control of the molecule with the minimum thermal effect This type of coherent molecular control means that the molecule can become a good optical amplifier even in a very short wavelength range, and can become a new coherent x-ray source.(4) An amplifier in the vacuum ultraviolet spectral region using rare gas excimers has been constructed based on the knowledge of the last year research accomplishment. A compact discharge laser device realized the Kr excimer laser operation at 147 nm for the first time.(5) The interaction between vacuum ultraviolet light and silicon has been investigated. Silicon as a basic material in the semiconductor industry has been used as a demonstration material. By irradiating the vacuum ultraviolet emission on a silicon wafer, a natural oxide layer has been removed and the surface flatness was dramatically improved. This is mainly attributed to the high photon energy of the vacuum ultraviolet light. Impurities on the silicon surface were successfully removed by the same light emission. In addition to the surface modification, a high quality oxide layer has been homogeneously produced on a silicon wafer at room temperature by using TEOS and vacuum ultraviolet emission. The surface quality was so high that those materials could be used in the semiconductor industry. Less