Absolute frequency measurements of the molecular iodine hyperfine transitions at 535 nm

We report absolute frequency measurements of the a1, a10, and a15 hyperfine components of molecular iodine P(28) 30-0 line at 535 nm. A frequency-doubled 1070 nm Nd:GdVO4 laser is frequency stabilized to a hyperfine component of I2 using the third-harmonic demodulation technique. The frequency stability of 3×10−12 is achieved at 10 s averaging time when its frequency is stabilized to the a1 component. An optical frequency comb is used to measure its absolute frequency. The pressure shift is investigated to obtain the absolute frequency at zero pressure. The effect of pressure and power broadening of the a10 component are also investigated. This light source can be used for investigating parity nonconservation effect in atomic thallium.