UV Laser Crystal Boost
- Chinese researchers developed a new ultraviolet laser crystal that improves precision for nuclear clocks by about 1,000×. (x.com) - The team says this precision jump could enable GPS‑free navigation options in space and underwater environments. (x.com) - Coverage frames the advance as a potential enabling tech for timing and navigation where GPS signals are unavailable. (x.com)
A clock needs a steady beat, and nuclear clocks need an ultraviolet laser tuned to about 148 nanometers; a Chinese team says a new crystal can get there. (scmp.com) The target is thorium-229, a rare isotope whose nucleus can be excited by light near 148.4 nanometers. In May 2024, researchers reported the resonance at 148.3821 nanometers in a calcium fluoride crystal, giving the field a precise wavelength to aim at. (pubmed.ncbi.nlm.nih.gov) Nuclear clocks differ from today’s atomic clocks by using changes inside the nucleus instead of changes in electrons around it. Nature reported on March 20, 2026, that clocks built this way could be tested this year because the nucleus is less disturbed by its environment. (nature.com) The new result comes from Pan Shilie’s team at the Xinjiang Technical Institute of Physics and Chemistry. The group reported in Advanced Materials in January that its fluorinated borate crystal could convert laser light down to 145.2 nanometers, shorter than the roughly 150-nanometer limit of the older potassium beryllium fluoroborate crystal. (scmp.com) That matters because the thorium-229 transition sits at 148.4 nanometers, so a crystal that can phase-match below that threshold clears a basic materials hurdle for compact laser systems. The Xinjiang team also reported conversion efficiency several times higher than standard materials, according to the South China Morning Post’s account of the paper. (nature.com) (scmp.com) The field has been moving on several fronts at once. A Nature paper published on February 11, 2026, described a continuous-wave vacuum-ultraviolet laser at 148.4 nanometers with projected linewidth below 100 hertz, a five-orders-of-magnitude improvement over earlier single-frequency lasers below 190 nanometers. (nature.com) Other teams are also trying to make the clocks practical rather than purely laboratory devices. In December 2024, researchers reported thorium fluoride thin films that used micrograms of thorium-229 and were designed for integration with photonics platforms and nanofabrication tools. (nature.com) A clock this stable could be used as a local timing reference when satellite signals are weak, blocked or unavailable. The applications most often cited are deep-space probes and underwater navigation, where Global Positioning System signals do not reliably reach. (scmp.com) The remaining step is the same one that has slowed the field for years: turning separate advances in crystals, lasers and thorium targets into one working device. For now, the new crystal is best understood as another piece of hardware that brings the 148-nanometer clock closer to a buildable instrument. (nature.com 1) (nature.com 2)
