1013W/cm2 Focusability of a High Average Power Glass Laser

HIgh Repetition and high EXcitation Solid state laser (HIREXS) of Zigzag optical pass slab geometry has been designed and developed for an application to the soft X-ray generation such as X-ray lithography. Design and performances of a zigzag optical path laser with a 230x65x5mm Nd:glass slab are described. The single pulse output energy of 98.9J was obtained at slope efficiency of 2.9% at 1.05μm wavelength. The laser beam divergences measured in the directions of width and thickness of the laser glass were about lmrad and 2mrad, respectively, without the transverse mode control. The maximum laser stored energy of 26J with the stored efficiency of 0.65% at 4kJ pumping was obtained. Q-switch operation of this laser resulted in 20J output at a pulse with of 28ns which results in the laser extraction efficency of 77%. The focused intensity was achieved 7x1012W/cm2. A water-cooled laser slab of silicate glass LSG-91H of the same dimensions generates an output power of 45W at a repetition rate of 3Hz.