Scientists have developed a new type of crystal, marking significant progress in the field of vacuum ultraviolet laser light, according to the Xinjiang Institute of Physics and Chemistry of the Chinese Academy of Sciences.
The team successfully overcame major technical challenges in growing large crystals and fabricating the device.
After conducting in-depth research on the fundamental theories and core technologies of vacuum ultraviolet nonlinear optical materials, a research team from the institute successfully developed ammonium fluorooxoborate (ABF) crystals. Their findings were published in the journal Nature on Thursday (January 29).
By leveraging birefringent phase-matching technology, they successfully achieved, for the first time, direct frequency doubling to produce a vacuum ultraviolet laser at a wavelength of 158.9 nm.
This achievement provides a new material system crucial for the development of compact and efficient all-solid-state vacuum ultraviolet lasers, which are expected to play a strategic role in precision manufacturing and advanced scientific research.
Nonlinear optical crystals are a core component for producing such lasers, as their properties directly determine the output wavelength and conversion efficiency. For decades, potassium beryllium fluoroborate (KBBF), pioneered by a team of Chinese scientists led by academician Chen Chuangtian in the 1990s, has been a key material.
KBBF remains the only practical crystal capable of producing laser output below 200 nm through direct frequency doubling.
As laser technology applications continue to expand, discovering new crystals that also exhibit high vacuum ultraviolet transmittance, strong nonlinear optical response, large birefringence, and excellent growth properties remains a persistent scientific challenge in this field.
To address this challenge, the research team proposed an innovative fluorination-based design and performance regulation mechanism, developing a series of high-performance crystals, with ABF as a prime example.
Building on this theoretical breakthrough, they then mastered crystal growth techniques to obtain centimeter-sized ABF single crystals with high optical quality. The ABF crystals achieved phase matching down to a record-shortest wavelength of 158.9 nm, setting a new standard for vacuum ultraviolet laser output through birefringence phase matching.
This breakthrough in ABF crystals represents a major achievement for China in the field of important vacuum ultraviolet nonlinear optical materials and strengthens the country's position as a world leader in this field.
Going forward, the researchers will continue their work on stabilizing ABF crystal growth, improving device processing, and exploring laser source applications. The goal is to develop an all-solid-state vacuum ultraviolet light source with even shorter wavelengths and higher power, thus providing strong support for advanced precision manufacturing and scientific research equipment.
