Off-axis multipass amplifier as a large aperture driver stage for fusion lasers

Abstract

A multipass amplifier configuration is described which has potential as a large aperture, high gain driver stage for fusion laser systems. We avoid the present limitations of large aperture switches by using an off-angle geometry that does not require an optical switch. The saturated gain characteristics of this multipass amplifier are optimized numerically. Three potential problems are investigated experimentally, self-lasing, output beam quality, and amplified spontaneous emission output. The results indicate comparable cost for comparable performance to a linear chain, with some operational advantage for the multipass driver stage.

Laser, chirped pulse amplification, ultrafast optics, and Nobel Prize in Physics

“…第一个具有现 代放大器几乎全部细节的再生放大器是1980年加州大学劳 伦斯˙利弗莫尔实验室(在劳伦斯辐射实验室之后的劳伦 斯˙利弗莫尔国家实验室的前身)的Murray和Lowdermilk [17] 利用Nd : YAG(掺钕的钇铝石榴石)实现的. 1981年, 劳伦 斯˙利弗莫尔国家实验室的Murray等人 [18] 发表了一篇对 多通放大器进行详细讨论的文章. 此时放大器的输出脉冲 能量受到激光介质以及其他光学元器件破坏阈值的限制 而不能太高.…”

An efficient off-axis multi-pass Nd:glass amplifier utilizing a birefringence crystal

“…Moreover, due to there being no round trip in the amplifier, self-oscillation can be effectively suppressed [13]. However, this kind of amplifier suffers from vignetting resulting from the required off-axis angle, which reduces the beam diameter for a given amplifier aperture and limits the passes [14]. This is why in most huge laser facilities, such as OMEGA [15], HELEN [16] and NIF [17], off-axis four-pass amplifiers are used for preference.…”

Angular spectrum symmetry for beam-path design in laser fusion facility

“…High energy extraction efficiency is desired to reduce the costs, which is essential for fusion-class facility design. To obtain high extraction efficiency in laser fusion facility, multipass amplification technique was adopted since 1980s [4,5]. Most of the facilities at this stage in the world are designed with multi-pass architecture, including, for example, the National Ignition Facility in America [6][7][8][9][10][11], the Laser Mégajoule in France [12][13][14] and the Shenguang-Ш Facility (SG-Ш) in China [15,16].…”