Two-photon resonant optical processes in atomic potassium

Two-photon resonant optical processes, using potassium ns2S1/2 states (7 ≤ n ≤ 20), are investigated in detail by a pulsed dye laser. About 100 coherent lines between 288–422 nm are generated through the processes ωUV ± ωIR = 2ωL and [Formula: see text]. The strongest lines (near mP–4S transitions) are formed by parametric oscillation and are generally split into components that are frequency shifted relative to atomic transitions. About 70 lines are generated by six-wave mixing processes and 15 other lines by four-wave mixing processes. The wavelengths, relative intensities of the lines, and the components of the strongest lines are explained with a theoretical analysis based on the wave equation, atomic polarization, and phase-match condition for both wave-mixing processes and parametric oscillations.