Blue laser induced bright red fluorescence in hot cesium vapor

We have observed laser-induced fluorescence using 456 nm laser radiation, resonant with the 6S${}_{1/2}\to$ 7P${}_{3/2}$ transition in Cs atoms. It includes red emission lines in the range of 580-730 nm and a prominent line at 852 nm corresponding to the 6P${}_{3/2}\to$ 6S${}_{1/2}$ transition. A T-shaped all-sapphire cell with a length of 1 cm, containing Cs atomic vapor and capable of being heated up to 500 °C, was used. The laser-induced fluorescence (LIF) power at 852 nm was investigated as a function of the cell temperature. The maximum LIF power was achieved at 130 °C, while a significant decrease was observed around 300 °C. At 130 °C, the Doppler-broadened LIF spectrum at 852 nm exhibited self-conversion, resulting in the formation of two distinct peaks within the spectrum. The LIF power at 852 nm was also studied as a function of the 456 nm radiation power. The Cs cell demonstrated potential as an efficient optical filter and down-converter, effectively transforming 456 nm radiation into 852 nm radiation.