Simple efficient traveling-wave excitation of short wavelength lasers using a conical pumping geometry.

A conically-shaped optical pumping geometry can be used to efficiently extract laser energy from an inverted population in the presence of strong amplified spontaneous emission. The ratio of the stimulated emission to absorption cross section of the active medium and the requirements of flux from the pumping source to make such a laser are derived. An analysis based on these requirements suggests that a 65 mJ pulse of 37.2 nm laser energy at an efficiency of 0.4% can be extracted from Na vapor photoionized with radiation from a 1.06micron laser-produced plasma using this simple pumping geometry.