Frequency measurement of the 260-THz (1.15-microm) He-Ne laser

Absolute infrared frequency measurement has been extended to 260 THz with the measurement of the strong 1.15-microm laser line in (20)Ne. The frequency was synthesized in nonlinear crystals of CdGeAs(2) and Ag(3)AsS(3) from stabilized CO(2) lasers and the 1.5-microm laser line in (20)Ne. The measured frequency is nu(20)Ne, 1.15 microm = 260.103 284(30) THz.