Description, Performance, and Wavelengths of Iodine Stabilized Lasers

A description is given of lasers stabilized to components of the ^129I_2 spectrum in the region of the 633-nm laser lines for ^3He–^20Ne and ^3He–^22Ne. Relationships between operational characteristics such as power output, peak size, and peak width are shown, along with their relationships to some of the controllable parameters such as excitation level, iodine absorption, and iodine pressure. We found an iodine pressure broadening of about 13 MHz/Torr with a 2.6-MHz zero-pressure intercept. The frequency shift associated with iodine pressure is roughly 2 × 10^−9ν/Torr to the red. Power broadening and power shifts are small, about a 10% increase in width and about 2 × 10^−11ν variation in frequency for a fivefold to sixfold increase in power. These lasers exhibit a frequency stability for 10-sec sampling time of about 2 × 10^−12ν and a resetability of about 1 × 10^−10ν. The absolute vacuum wavelength for one iodine component has been measured against the ^86Kr standard—^3He–^20Ne:^129I_2, k λ = 632 991.2670 A 0.0009 pm. The wavelengths of several other iodine components have been determined by measuring the frequency difference between them and the ^129I_2, k component. Among these are ^3He–^22Ne:^129I_2, B λ = 632 990.0742 ± 0.0009 pm: and ^3He–^20Ne:^127I_2, i λ = 632 991.3954 ± 0.0009 pm. These results were obtained using the Rowley-Hamon model for asymmetry in the krypton line and assume that the defined value for the standard is associated with the center of gravity of the line profile. The indicated uncertainties are statistical. No allowance has been included for imperfect realization of the krypton standard or for uncertainty in the asymmetry model.