Laser-Based Measurements for Time and Frequency Domain Applications

Time and frequency measurements with pulsed laser systems 4 63

same group has proposed to use a CO

2

laser that is frequency locked to a ro-vibrational

transition of SF

6

as another possible reference clock at 10 µm [646]. In both cases, the same

exp e rimental approach was used to link the IR frequencies to the Cs primary standard: a

SFG nonlinear up-conversion process involving the CO

2

laser and visible radiation gener-

ates radiation still in the visible, whose frequency can be measured against the OFCS. In

the CO

2

/OsO

4

exp e riment, the SFG signal laser was an 852 nm OFCS-phase-locke d diode

laser, and the generated 788 nm SFG pump was used to phase-lock another diode laser at

this wavelength. In this way, the beat-note SNR between the OFCS a nd the ...