By means of a novel experimental design called double-massive-target coupling, significant amplification of five lasing lines was observed with wavelengths (λ) of 19.6, 23.2, 23.6, 24.7, and 28.6 nm from 3p–3s transitions in Ne-like Ge ions at an irradiance of 1.2 × 1013 W/cm2 on the axis of an elongated plasma column. The maximum gain-length product (GL) values achieved were greater than 14 for 2 of the 5 lasing lines at 23.2 and 23.6 nm. Temporally resolved measurements of x-ray laser spectra indicate that the duration of the gain was ~0.8 ns, which is comparable with the Gaussian driving laser pulse width of 1 ns (FWHM) in our experiments. The measured divergence and refraction angles of the x-ray laser beam at 23.6 nm are presented. The dimension and position of the gain region are estimated.
© 1992 Optical Society of America
Original Manuscript: August 17, 1990
Revised Manuscript: June 17, 1991
Published: March 1, 1992
Shiji Wang, Zunqi Lin, Guoping Zhang, Jiatian Sheng, Shusen Wang, Yuan Gu, Guanlin Zhou, Wannian Chen, Huimin Peng, Tanxin Zhang, Dianyuan Fan, Songyu Yu, Sizu Fu, Yunfeng Shao, Yuanlong Ni, Jiang Wu, Zhengliang Zhou, Guoqiang Han, and Zucong Tao, "Experimental investigation of high-gain Ne-like Ge soft-x-ray laser by double-massive-target coupling," J. Opt. Soc. Am. B 9, 360-368 (1992)