Microwave signal generation with optical injection locking

Two single-mode laser diodes have been injection locked to the +1 and -1 diffracted orders of a 4.6-GHz acousto-optical modulator. The measured locking bandwidth was 3 GHz for a locking gain of 35 dB. The microwave signal at 9.2 GHz had a measured linewidth of less than a few hertz. We used this system to drive stimulated Raman transitions between the cesium ground-state hyperfine levels. We observed Ramsey fringes and used them to characterize the microwave signal phase noise.