Laser wavelength and frequency standards based on He-Ne lasers and I2129vapor

It is shown that a very precise wavelength standard can be developed based on the use of an He³-Ne²⁰laser that is stabilized on an inverted Lamb dip associated with a hyperfine component of the B³II+ou← X¹Σ+ogelectronic transition in I2¹²⁹vapor. Extensive work has shown that when I2¹²⁹is used instead of I2¹²⁷, many of the inverted Lamb dips are sufficiently prominent to serve as steady and accurate frequency markers for stabilizing the laser. Lasers so stabilized have proven to have a stability and resettability (accuracy) of at least 1 part in 10¹¹. This represents considerable improvement over the present 0.606-µm Kr⁸⁶wavelength standard. Thirty-eight inverted Lamb dips corresponding to the hyperfine structure of I2¹²⁹have been observed with the 6328-Å He³-Ne²⁰laser over a spectral range of 650 MHz, demonstrating that this spectroscopic technique has sufficient resolution to resolve very small splittings.