全固态深紫外相干光源在前沿科学、高技术等领域均有重要应用。产生全固态深紫外相干光源的一种有效而可行的技术途径是将商业化的可见、近红外全固态激光作为基频光源，通过非线性光学晶体的多级变频技术产生深紫外激光。本文系统地介绍了深紫外非线性光学晶体及全固态深紫外相干光源的研究进展。主要以KBBF晶体为代表，详细介绍了发现KBBF晶体的过程，晶体生长技术，棱镜耦合器件技术，KBBF晶体的主要光学性质以及产生深紫外相干光源的能力，同时证实了KBBF晶体是目前能使用直接倍频方法实现深紫外激光输出的非线性光学晶体。此外，文中还详细介绍了基于KBBF晶体及棱镜耦合技术的深紫外相干光源的应用情况，尤其是在超高分辨率光电子能谱仪方面的应用及取得的重要成果。最后，展望了深紫外非线性光学晶体及全固态深紫外激光技术的发展方向。

All-solid-state deep ultraviolet coherent light sources have important applications in frontier science, high technology and many other fields. An effective and feasible technical approach is to use commercially available visible and near-infrared all-solid-state lasers as the fundamental frequency light source to generate a deep ultraviolet laser through cascaded frequency conversion using nonlinear optical crystals. This paper reviews the research progress of deep ultraviolet nonlinear optical crystals and all-solid-state deep ultraviolet coherent light sources. Taking KBBF crystals as the representative example, their discovery, crystal growth, corresponding prism-coupled device technology, main optical properties, and ability to generate deep ultraviolet coherent light are each introduced. It was proven that KBBF crystals are excellent nonlinear optical crystals that can achieve deep ultraviolet laser output through direct frequency doubling. The applications of deep ultraviolet coherent light sources based on KBBF crystals and prism-coupled technology are discussed, with special focus given to ultra-high resolution photoelectron spectrometers. Finally, the future direction of the development of deep ultraviolet nonlinear optical crystals and all-solid-state deep ultraviolet laser technology are given.