LAUSR

We investigated nonlinear optical processes driven by superfluorescent (SF) fields and their controllability with external laser fields. Cesium atoms were excited from the $6S$ ground state to the $8P$ state by a femtosecond laser pulse. The cascaded SF decay, $8P\ensuremath{\rightarrow}8S\ensuremath{\rightarrow}7P$, created coherence between the $7P$ and ground states, and led to the emission of a 455-nm pulse. A nanosecond laser pulse was applied to switch the $8S\ensuremath{\rightarrow}7P$ transition to the $8S\ensuremath{\rightarrow}6P$ one and newly generate an 852-nm pulse. At the same time, the nanosecond pulse suppressed the 852-nm emission through the inhibition of the development of the SF field between the $8P$ and $8S$ states, which led to the saturation of the 852-nm power with the increase of the nanosecond pulse power. The presented results offer an approach to investigate cooperative radiation processes in many-body systems and to develop an alternate light source.