Visible lasers are sought for in a variety of applications. They are required in fields as diverse as medicine, materials processing, display and entertainment technology and many others. Moreover, in contrast to infrared lasers, they enable very simple and efficient access to the UV spectral range by a single frequency doubling step. Currently, the choice of direct visibly emitting lasers is limited: The ‘green gap’ prohibits the development of semiconductor lasers with emission in the green and yellow spectral range and only few laser active ions allow for efficient visible lasing. In particular trivalent praseodymium (Pr³⁺) and terbium (Tb³⁺) ions have been shown to be the most successful candidates for efficient high power visible solid-state lasers. Compared to semiconductor lasers, solid-state lasers also provide other advantages, e.g., in terms of energy storage in Q-switched operation as well as beam quality at high output power.

In recent years, visibly emitting solid-state lasers have seen a revival enabled by the increasing commercial availability of GaN-based blue emitting pump diodes and an ever-increasing number of publications evidences the vivid research activities in this field. Still, due to the relatively short history of diode-pumped visible solid-state lasers, these are still in an early stage of their development and up to now only few direct visibly emitting solid-state lasers with comparably low output power are commercially available. However, we are convinced that visibly emitting solid-state lasers based on Pr³⁺ and Tb³⁺ have the potential for 100-W-class continuous wave output power levels as well as sub-ns pulse durations in Q-switched and sub-ps-pulse durations in mode-locked operation, which would qualify them to fulfil the requirements of most of the applications named above.

In this work, we review the state of the art of continuous wave and pulsed visibly emitting solid-state lasers and amplifiers based on Pr³⁺ and Tb³⁺ as the active ion. After an introduction, we briefly review the spectroscopic properties of these two ions and their particularities for laser operation as well as the requirements for suitable host materials. In the third chapter, we present the state of the art in the field of continuous wave Pr³⁺-lasers emitting in the cyan-blue, green, orange, red, and deep-red spectral range based on fluoride, glass, and oxide host materials and discuss prospects for further power scaling. The fourth chapter is devoted to the current state of Tb³⁺-based continuous wave green and yellow emitting solid-state lasers. In the fifth and sixth chapter we give an overview over existing pulsed visibly emitting solid-state lasers in Q-switched and mode-locked operation mode, respectively. Finally, the seventh chapter is devoted to pulse amplifiers for ultrafast visible lasers before this review closes with a short conclusion.

在各种应用中寻找可见激光。它们在医药、材料加工、显示和娱乐技术等众多领域都有所需要。此外，与红外激光器相比，它们可以通过单倍频步骤非常简单有效地进入紫外光谱范围。目前，直接可见发射激光器的选择是有限的：“绿色间隙”禁止发射在绿色和黄色光谱范围内的半导体激光器的发展，并且只有少数激光活性离子允许有效的可见激光发射。特别是三价镨 (Pr ³⁺ ) 和铽 (Tb ³⁺) 离子已被证明是高效高功率可见固态激光器最成功的候选者。与半导体激光器相比，固态激光器还具有其他优势，例如在 Q 开关操作中的能量存储以及高输出功率下的光束质量方面。

近年来，随着基于 GaN 的蓝色发射泵浦二极管的商业可用性不断增加，可见发射固态激光器得到了复兴，并且越来越多的出版物证明了该领域的生动研究活动。尽管如此，由于二极管泵浦可见固态激光器的历史相对较短，这些激光器仍处于发展的早期阶段，到目前为止，只有少数输出功率相对较低的直接可见发射固态激光器可商用。^{然而，我们确信，可见发射基于 Pr 3+}和 Tb ³⁺的固态激光器具有 100 W 级连续波输出功率水平以及 Q 开关中的亚 ns 脉冲持续时间和锁模操作中的亚 ps 脉冲持续时间的潜力，这将使它们有资格满足大多数的要求上面提到的应用程序。

^{在这项工作中，我们回顾了基于 Pr 3+}和 Tb ³⁺作为活性离子的连续波和脉冲可见发射固态激光器和放大器的最新技术。在介绍之后，我们简要回顾了这两种离子的光谱特性及其在激光操作中的特殊性以及对合适主体材料的要求。在第三章中，我们介绍了基于氟化物、玻璃和氧化物在青蓝色、绿色、橙色、红色和深红色光谱范围内发射的连续波 Pr ³⁺激光器领域的最新技术。主体材料并讨论进一步功率扩展的前景。^{第四章专门介绍Tb 3+}的现状基连续波绿色和黄色发射固态激光器。在第五章和第六章中，我们分别概述了现有的 Q 开关和锁模操作模式下的脉冲可见发射固态激光器。最后，第七章专门讨论用于超快可见光激光的脉冲放大器，然后以一个简短的结论结束本综述。