Polychromatic and collimated lights generated by nondegenerate four-wave mixing in cesium vapor

We demonstrate the generation of polychromatic and collimated lights at 456 nm, 459 nm, and 761 nm based on cesium (133Cs) 6S1/2 - 6P3/2 - 8S1/2 - 7P3/2, 7P1/2, 6P1/2 - 6S1/2 multi-diamond-type atomic system via two-photon excitation with two IR pump lasers at 852 nm and 795 nm. The 456 nm, 459 nm (7P3/2, 7P1/2 -, 6S1/2) collimated blue lights result from the self-seeded four-wave mixing process (FWM), and the 761 nm coherent light (8S1/2 -, 6P1/2) is from a seeded FWM process with the injection of a third laser at 895 nm. We measure the dependency of generated polychromatic fields on the temperature of 133Cs vapor cell and the powers of input lasers, clearly demonstrating the competition between the self-seeded FWM and seeded FWM, as they share the same excitation path. This work is helpful to further produce entangled multi-color photons for quantum communication.