GoKawiilPTB team details 229.8 nm laser setup for thorium-229 nuclear clock feedback loop
Researchers describe a laser interrogation system built around a commercial frequency-quadrupled diode laser that reaches roughly 500 mW at 296.8 nm, used to probe a thorium-229-doped crystal sample. The setup combines offset-frequency phase locking and Pound-Drever-Hall stabilization to a reference cavity, with a photomultiplier tube detecting fluorescence signals inside a vacuum chamber, and the clock laser's frequency also compared against an optical frequency comb.