FREQUENCY REFERENCE DEVICES AND METHODS OF PROVIDING FREQUENCY REFERENCES

摘要

A frequency reference device has a population of atoms or ions held in a vapour cell providing a first frequency reference signal by virtue of at least one electronic transition. A driving means provides a driving signal to the population of atoms or ions to promote the electronic transition. A detector detects a characteristic of the first frequency reference signal. The driving means includes a laser diode and a negative differential resistance oscillator. The detected characteristic of the first frequency reference signal is used to control the driving signal.