A 2 ps pulse derived by frequency doubling the amplified output of a CW mode-locked dye laser has been used to probe the gain characteristics of XeCl in the 308 nm region. Energy saturation parameters were measured for the four main laser transition. The gain kinetics of XeCl were investigated by observing the temporal gain recovery after the passage of a saturating picosecond pulse, and the contribution of the various relaxation processes to the XeCl gain dynamics is discussed. Evidence suggests that vibrational relaxation in the upper laser level is incomplete during the effective lifetime of XeCl*. Taken together, these measurements have permitted the determination of a stimulated emission cross section of general utility. To demonstrate the potential of XeCl for high power amplification, a picosecond pulse was amplified to a power of ∼20 GW.

Picosecond amplification and kinetic studies of XeCl

Measurement of the surface emmissivity of turbid waters

Considerable improvements in overall efficiency of a compact UV‐preionized discharge XeCl laser have been achieved by possible operation at relatively low charging voltages V for high pressure P HCl/Xe/Ne mixtures. A peak overall efficiency of 2.9% has been obtained with the output energy of 280 mJ at V=18 kV and P=4 atm. A maximum output energy of 680 mJ has been extracted with the overall efficiency of 1.8% in 20‐ns (FWHM) pulses at P=6 atm and V=36 kV, corresponding to an energy density of 5.8 J/1. The efficient performance and simple design of the discharge XeCl laser with automatic preionization are described.

Efficient and compact discharge XeCl laser with automatic UV preionization

For interpreting thermal IR imagery of the ocean surface, the emissivity of the sea surface is usually assumed to be constant, approximately 0.98. However, the emissivity varies with the roughness of the sea surface, and the concentration and type of suspended particulates. The emissivity variations caused by the suspended sediments introduce significant errors in the satellite-derived temperature maps of turbid coastal waters. We measured in the laboratory the thermal IR emissivity of water as the suspended sediment concentration was varied from zero to extremely high values. The results indicated that increasing the sediment concentration decreases the spectral emissivity within the 8–14 μm waveband.

Measurement of the surface emissivity of turbid waters

A railgap has been developed which is triggerable by either corona or spark discharges. Trigger voltage and energy were 15 kV and 20 mJ, respectively. The switch was successfully tested over the range 15–35 kV, providing a channel spacing of about 1/cm.

Multichannel switch triggered by low‐voltage auxiliary discharges

Experimental results of a Blumlein‐discharge‐excited XeCl laser are reported in this letter. The maximum output pulse energy was over 400 mJ. The overall efficiency and specific output energy were 1.7% and 5 Jl, respectively. Experiments have shown that the lasing spectrum of XeCl varied with the total pressure. With a total pressure of 500 Torr, 108 discrete laser lines including two new vibrational bands, (0,4) and (1.7), were obtained. The effects of the partial pressure of Xe, the Blumlein charging voltage, and the total pressure on the output energy were also investigated.

Efficient operation of Blumlein‐discharge‐excited XeCl laser

The results of studies on XeBr laser output behaviour are reported; in this laser, HBr, BBr 3 and C 2 F 4 Br 2 are used as bromine donor. The maximum energy obtaind is 6 mJ. Volume energy density and efficiency are 0.4J/L, 0.14% respectively. Filially, we propose a way for improving the lasing output level.

ELECTRIC DISCHARGE PUMPED XeBr LASER WITH HIGH POWER AND HIGH EFFICIENCY

The coherent radiation of ten species, F,Ne,N 2 ,N 2 + ,XeF,XeCl,XeBr, KrF, KrCl, ArF were obtained by using a high pressure UV pre-ionization dischage device and varing lasing gases in a laser The laser parameters and the output behaviour were also given

Liu Miao-hong

Papers

Efficient operation of Blumlein‐discharge‐excited XeCl laser

ELECTRIC DISCHARGE PUMPED XeBr LASER WITH HIGH POWER AND HIGH EFFICIENCY

Discharge-pumped multiwavelength laser