Frequency characteristics of collimated blue light generated by four-wave mixing in cesium vapor

The frequency evaluation of collimated blue light (CBL) generated by parametric four-wave mixing (FWM) in hot atomic vapor is presented. The cesium (Cs-133) atoms are excited from the 6S(1/2) ground state to 8S(1/2) excited state with the 852 and 795 nm pump lasers, producing an optical field at 4.2 mu m through an amplified spontaneous emission via population inversion on the 8S(1/2 )-> 7P(3/2) transition and the 456 nm CBL via FWM on the 7P(3/2 )-> 6S(1/2) transition. The frequency shift of 456 nm CBL has been measured by velocity-selective optical pumping spectral technique when the frequency of any one of two pumping lasers is tuned. The ratio of the frequency shift of 456 nm CBL to the two-photon frequency detuning of two pumping lasers is 0.8912, implying that the generated 4.2 mu m light frequency is also correspondingly shifted. (c) 2024 Optica Publishing Group