Competition of collimated ultraviolet lights generated by four-wave mixing process in Cs vapor

Using the two-color two-photon scheme, caesium (Cs) atoms were excited to (or around) the 112D5/2 level, generating terahertz (THz) and infrared (IR) radiations. then, a series of collimated ultraviolet (UV) lights were obtained through the four-wave mixing process. There was a competition among the collimated UV lights. The pump intensity directly affects the refractive index of Cs vapor at the pump laser wavelength, affecting the phase matching. Under the good phase-matching condition, 334.7 nm (UV1) and 339.8 nm (UV2) collimated lights were used to study the competition between ∼1.1 THz (THz1) and ∼ 20.9μm (IR2) radiations. After tuning the wavelength combination of the pump lasers, the intensities of THz and IR radiations were affected by the competition among parametric four-wave mixing, stimulated Raman scattering, and amplified spontaneous emission.