Abstract

Lasing in 3p—3s transitions in neonlike Cu¹⁹⁺ and Ge²²⁺ ions has been achieved for the first time. The plasmas were created by line focusing the NRL Pharos III Nd:glass laser (1.05 μm, 350–500 J, 2-ns FWHM) to a width of 200 μm and various lengths up to 24 mm for an irradiance of (4–6) × 10¹²W/cm². Thin (100–300-nm) supported film as well as thicker (1.3-μm) foil and solid slab targets are used. For copper, a gain coefficient of 2.0 ± 0.2 cm⁻¹ for the J = 0—1 lasing line at 22.111 nm was measured to be greater than that of 1.7 ± 0.2 cm⁻¹ for the J = 2—1 lines at 27.931 and 28.467 nm in agreement with theoretical expectations. The measured wavelengths (±0.004 nm) agree within 0.04 nm with recent calculations. Data of this nature for the corresponding lines in germanium at 19.61, 23.24, and 23.63 nm are presented. These data tend to support electron-collisional excitation as a primary pumping mechanism. Success with such a variety of targets indicates that the lasing takes place in a less dense ablating plasma.

© 1987 Optical Society of America