The absolute frequency of the 473-THz He–Ne laser (633 nm), stabilized on the g or i hyperfine component of the 127I2 11–5 R(127) transition, was measured by comparing its frequency with a known frequency synthesized by summing the radiation from three lasers in a He–Ne plasma. The three lasers were (1) the 88-THz CH4-stabilized He–Ne laser (3.39 μm), (2) a 125-THz color-center laser (2.39 μm) with its frequency referenced to the RII(26) 13C18O2 laser, and (3) the 260-THz He–Ne laser (1.15 μm) referenced to an I2-stabilized dye laser at 520 THz (576nm). The measured frequencies are 473 612 340.492 and 473 612 214.789 MHz for the g and i hyperfine components, respectively, with a total uncertainty of 1.6 parts in 1010. The frequency of the i component adjusted to the operating conditions recommended by the Bureau International des Poids et Mesures is 473 612 214.830 ± 0.074 MHz.
© 1983 Optical Society of America
Original Manuscript: November 2, 1982
Published: March 1, 1983
D. A. Jennings, J. L. Hall, H. P. Layer, C. R. Pollock, F. R. Petersen, R. E. Drullinger, K. M. Evenson, and J. S. Wells, "Direct frequency measurement of the I2-stabilized He–Ne 473-THz (633-nm) laser," Opt. Lett. 8, 136-138 (1983)