Frequency stabilized ammonia laser system for probing the 24 THz clock transition of a trapped barium ion

The design, performance and frequency stability of an optically pumped ammonia laser operating on the sP(8,6) transition of /sup 15/NH/sub 3/ at 12.48 /spl mu/m wavelength are discussed. The short term frequency stability was tested by heterodyning two similar lasers. An Allan deviation of 2/spl middot/10/sup -11/ for averaging times from 10/sup -4/ s to 1 s was achieved for the free running laser. Absolute values of the laser frequency were obtained by measuring against the NRC H4 hydrogen maser standard with the help of the NRC frequency chain. A scan across a narrow fine-structure transition in a single trapped barium ion provided a final test for the overall stability.<
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