Reviewed by Frances BriggsFeb 2 2026
A new crystal, ABF, could be a major breakthrough in producing ultraviolet laser light in a vacuum.
Image Credit: Alexander Sobol/Shutterstock.com
Researchers from Xinjiang Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences created the novel material. Their work has been published in the journal Nature.
Following extensive investigation into the foundational theories and essential technologies of vacuum ultraviolet nonlinear optical materials, a group of researchers from the institute successfully synthesized an ammonium fluorooxoborate (ABF) crystal.
The team addressed significant technical obstacles in the growth of large-sized crystals and the fabrication of devices. By employing birefringent phase-matching technology, they accomplished, for the first time, direct frequency-doubling to produce a vacuum ultraviolet laser at a wavelength of 158.9 nm.
This accomplishment offers a vital new material system for the development of compact, efficient all-solid-state vacuum ultraviolet lasers, which are anticipated to have a strategic impact on precision manufacturing and advanced scientific research.
Nonlinear optical crystals serve as the fundamental elements for generating such lasers, as their properties directly influence the output wavelength and conversion efficiency. For many years, potassium beryllium fluoroborate (KBBF), which was developed by Chinese researchers under the leadership of academician Chen Chuangtian in the 1990s, has been recognized as a significant material.
It was the sole practical crystal capable of producing laser output below 200 nm via direct frequency doubling.
As laser technology applications continue to grow, the quest for a new crystal that can simultaneously demonstrate high vacuum ultraviolet transmittance, a strong nonlinear optical response, substantial birefringence, and excellent growth characteristics remains a significant scientific challenge in the discipline.
The research team introduced an innovative fluorination-based design along with a performance-regulation mechanism, leading to the development of a series of high-performance crystals, with ABF being a primary example.
Building on this theoretical advancement, they successfully mastered crystal growth techniques to produce centimeter-sized, high-quality optical ABF single crystals. The ABF crystal can achieve phase matching down to an unprecedented wavelength of 158.9 nm, thereby establishing a new standard for vacuum ultraviolet laser output via birefringent phase matching.
This advancement in ABF crystals marks a significant accomplishment for China in the field of essential vacuum-ultraviolet nonlinear optical materials and strengthens the nation's leading position on the international stage in this field.
The researchers plan to continue their efforts to stabilize ABF crystal growth, enhance device processing, and investigate applications of laser sources. Their objective is to innovate all-solid-state vacuum ultraviolet light sources with even shorter wavelengths and greater power, thereby providing substantial support for advanced precision manufacturing and scientific research equipment.
Journal Reference:
Zhang, F. et al. (2026). Vacuum ultraviolet second-harmonic generation in NH4B4O6F crystal. Nature. DOI: 10.1038/s41586-025-10007-z. https://www.nature.com/articles/s41586-025-10007-z.