Optical frequency measurements with the global positioning system: tests with an iodine-stabilized He-Ne laser.

Global positioning system- (GPS-) referenced optical frequency combs based on mode-locked lasers offer calibrations for length metrology traceable to international length standards through the SI second and the speed of light. The absolute frequency of an iodine-stabilized He-Ne laser [127I2 R(127) 11-5 f component] was measured with a femtosecond comb referenced to a multichannel GPS timing receiver. The expected performance and limitations of GPS-referenced comb measurements are discussed.