I2 Stabilized He-Ne Lasers at 612 nm

We have investigated the properties of He-Ne lasers stabilized to saturated absorption features of either 127I2 or 129I2 at 612 nm. Using 129I2 we observe 25 strong, not yet reported, saturated absorption signals which are preliminarily attributed to hyperfine structure (HFS) components of the P(110) 10-2 transition of 129I2. Linewidths of 5.5 MHz fulwidth half medium (FWHM) and 1.2 MHz have been observed with I2 cells positioned inside and outside the laser cavity, respectively. Using intralaser cavity I2 cells the frequency difference of our lasers, stabilized independently to the 127I2 components o or r was 2.10-11¿.