What you are describing is essentially a "frequency chain" which was historically used for measuring the frequency of laser light. The idea is to start with a c

What you are describing is essentially a "frequency chain" which was historically used for measuring the frequency of laser light. The idea is to start with a cesium atomic clock which (by definition) has a frequency of 9 192 631 770 Hz. The frequency of the signal is then multiplied up using some non-linearity, and a phase locked loop is used to stabilize the output of a higher-frequency oscillator to the up-multiplied signal. This is repeated in multiple steps, until optical frequencies are reached. The laser frequency is then an exact multiple of the frequency of the atomic clock. This technique was for example used for the "last measurement" of the speed of light [1]. Later, the speed of light was defined to be exactly 299 792 458 m/s, so it is no longer possible to measure it (all lengths are now defined with respect to the speed of light and the frequency of a cesium clock). Frequency chains were monstrously complex experiments, since they contained all kinds of different oscillators in a wide range of frequencies that were linked with phase locked loops. Only a few were ever build, mainly by national metrology labs. The technique was made completely obsolete in 1999 when the optical frequency comb was invented. Frequency combs are lasers that directly link optical frequencies to radio frequencies without requiring intermediate steps. In 2005, Hall and Hänsch shared half of the Nobel Prize in Physics for the invention [2]. [1] https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.29.1346 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.29... [2] https://www.nobelprize.org/prizes/physics/2005/prize-announcement/ https://www.nobelprize.org/prizes/physics/2005/prize-announc...