Demonstration of a narrow-divergence x-ray laser in neonlike titanium.

Abstract

We report an observation of soft-x-ray lasing in Ti, at 326.5 \AA{}, based on recent experiments conducted on the Glass Development Laser (1.054 \ensuremath{\mu}m) at the Laboratory for Laser Energetics and the Nova laser (0.53 \ensuremath{\mu}m) at Lawrence Livermore National Laboratory. This Ti laser, which has been identified as a 3p\ensuremath{\rightarrow}3s transition in Ne-like Ti, is unusual in several ways; the J=0\ensuremath{\rightarrow}1, 3p\ensuremath{\rightarrow}3s transition is observed to be the dominant laser line in a Ne-like spectrum, the laser output has a very narrow divergence, and lasing is observed only in experiments where the main optical pulse is preceded by a low-intensity prepulse. We describe the experimental results and present evidence that suggests the gain is enhanced by resonant photopumping of the Ne-like Ti 2p\ensuremath{\rightarrow}4d transitions by 3s\ensuremath{\rightarrow}2p C-like and 3d\ensuremath{\rightarrow}2p N-like Ti lines, which results in lasing on the 3p\ensuremath{\rightarrow}3s transitions in Ne-like Ti.