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) 6S_1/2 - 6P_3/2 - 8S_1/2 - 7P_3/2, 7P_1/2, 6P_1/2 - 6S_1/2 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 (7P_3/2, 7P_1/2 → 6S_1/2) collimated blue lights result from the self-seeded four-wave mixing process (FWM), and the 761 nm coherent light (8S_1/2 → 6P_1/2) 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.