Miniature Frequency Standard Based On All-Optical Excitation And A Micromachined Containment Vessel
Original Publication Date: 2005-Oct-24
Included in the Prior Art Database: 2005-Oct-24
National Institute of Standards and Technology
Leo Hollberg: INVENTOR [+2]
A microwave frequency standard is provided which allows for miniatureization down to length scales of order one microon, comprising a modulaed light field originating from a laser that illuminates a collection of quantum absorbers contained in a micro-machined cell. The frequency standard of the present invention can be based on all-optical excitation techniques such as coherent population traping (CPT) and stimulated Raman scattering or on conentional microwave-excited designs. In a CPT-based embodiment, a photodetector detects a change in transmitted power through the cell and that is used to stabilize a external oscillator to correspond to the absorber's transition frequency by locking the laser modulation frequency to the transition frequency. In a stimulated Raman scattering (SRS) embodiment, a high-speed photodector detects a laser field transmitted through the cell beating with a second field originating in the cell. Both the locked laser modulation frequency and the beat frequency are very stable as they are referenced directly to the atomic transition.