Chinese scientists have pushed solid-state vacuum ultraviolet laser technology to a new milestone by achieving a record-short wavelength using a new specialized optical crystal.<\/p>\n
The breakthrough, which is hailed as a major advance in vacuum ultraviolet (VUV) laser technology was carried out by a research team at the Chinese Academy of Sciences (CAS). The team was led by Pan Shilie, PhD, a director at the academy\u2019s Xinjiang Technical Institute of Physics and Chemistry.<\/p>\n
For the project, Shilie relied on a non-linear optical crystal, known as ammonium fluorooxoborate (NH4BF4) or ABF. Using this material the team created a vacuum ultraviolet laser beam at a wavelength of 158.9 nanometers (nm), through direct frequency doubling.<\/p>\n
\u201cThe development of ABF paves the way for compact, efficient all-solid-state VUV lasers,\u201d the team stated. It could additionally enable applications across quantum computing, space platforms, chipmaking as well as precision manufacturing.<\/p>\n
New VUV laser record<\/p>\n
Vacuum ultraviolet light<\/a> typically covers all of the wavelengths between 120 and 240 nanometers. It is highly sought after for applications ranging from advanced spectroscopy and semiconductor manufacturing to quantum research.<\/p>\n Still, producing such light efficiently has long posed a challenge. While nonlinear optical frequency conversion is one of the most effective methods, progress has been constrained by the scarcity of suitable crystals.<\/p>\n Shilie stated that potassium beryllium fluoroborate (KBBF) was the only practical crystal capable of generating laser output<\/a> below 200 nanometers through direct frequency doubling. However, despite being highly effective, it posed limitations in crystal growth and device fabrication.<\/p>\n In contrast, the ABF crystal, designed and grown by Chinese scientists over more than a decade, overcomes many of these obstacles. <\/p>\n It combines properties that are rarely achieved in a single material, including high transparency in the vacuum ultraviolet range, a strong nonlinear optical response and sufficient birefringence for phase matching at extremely short wavelengths<\/a>.<\/p>\n \u201cThe ABF crystal is a novel material, entirely developed and patented by our institute, from initial design to crystal growth, to final laser output,\u201d Shilie pointed out<\/a>. \u201cABF not only achieves the shortest wavelength but also delivers the highest energy output and conversion efficiency to date.\u201d<\/p>\n Solid-state progress<\/p>\n The researchers first synthesized the ABF crystal in 2016. They spent a decade to grow it to centimeter-scale sizes with high optical quality. The efforts have made it suitable for real laser devices rather than just lab demonstrations. <\/p>\n By introducing fluorine to the borate crystal framework and carefully controlling the structure, the team outlined<\/a> a broader design strategy for discovering future vacuum ultraviolet nonlinear optical materials.<\/p>\n \u201cFuture optimization of crystal growth and processing techniques is expected to further enhance the laser\u2019s performance,\u201d Shilie said. Apart from the 158.9-nm wavelength, the ABF<\/a> achieved a nanosecond pulse energy of 4.8 millijoules (mJ).<\/p>\n It also reached a conversion efficiency approaching six percent. The team noted that the figures represent new records for vacuum ultraviolet lasers generated via second harmonic generation. The short wavelength means the ultraviolet light carries more energy, thus enabling new applications.<\/p>\n \u201cWe will use this directly generated laser to create new demand,\u201d Shilie revealed, adding that China is transforming into a manufacturing powerhouse that needs to lead and create opportunities. \u201cFor instance, in future space communications, there are many \u2018uncharted territories.’\u201d <\/p>\n