OPTICAL FREQUENCY COUNTING FROM THE UV TO THE NEAR IR

A method for measuring optical frequencies from the UV to the near IR relative to a microwave frequency standard is proposed. The concept is to measure the frequency difference of two known ratios (1/2 and 2/3) of an optical frequency f relative to the cesium clock. By employing optical parametric oscillators and wideband modulators to link the (1/2)f and (2/3)f frequencies, a precise and accurate optical frequency comb can be provided in the approximately 1-2-mu-m wavelength region. By using this comb, most optical frequencies from the UV to the near IR can be measured or synthesized. A configuration for measuring the frequency of the hydrogen 1S-2S transition is described.