Browsing by Author "ZHU, YUNPING"

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    BROADBAND TUNABLE EXCIMER LASER STUDIES
    (1987) ZHU, YUNPING
    The principal purpose of this work has been the studies of the broadband tunable excimer laser namely XeF(C $\to$ A). Wideband tunability of this excimer laser was first demonstrated with a simple compact dispersive stable cavity in a transverse e-beam pumped geometry. More recently, a series of experiments has been performed to control the XeF(C $\to$ A) by dye laser injection. In any low-gain, short-pulse laser systems, rapid build-up of the optical field within the resonator is critical to good laser performance and extraction efficiency. Simultaneous injection of a "seed" signal into the cavity with laser pumping excitation can create a much faster increase in the intensity of the optical field. This rapid build-up of the optical field will aid the competition against radiative emission from the high gain XeF(B $\to$ X) transition and non-radiative quenching of the XeF excimers by halogen donors and other constituents of the laser gas mixture. Efficient, ultranarrow (0.002 nm to 0.005 nm) spectral output from an electron-beam excited XeF(C $\to$ A) laser medium (Ar/Kr/Xe/F$\sb{2}$/NF$\sb{3}$ mixture) has been observed by injection tuning. Amplification of an injected tunable dye laser pulse was achieved throughout the entire blue-green spectral region from 435 nm to 535 nm. Several different confocal unstable resonator geometries with magnification of 1.05 to 1.23 were investigated. A maximum output of about 85 mJ was measured at 482.5 nm for a cavity with magnification M = 1.1, which corresponds to an energy density and intrinsic efficiency of 4.7 J/liter and $\sp\sim$5%, respectively. These values are comparable to those of UV rare gas-halide lasers. In order to gain a better understanding of the injection control process in XeF(C $\to$ A) laser, a semiempirical model using a pulsed regenerative amplifier approach has been established with good accuracy. A set of coupled rate equations are used for this purpose. Some key factors in cavity and pumping source design are addressed.