Compensation for inhomogeneous nonlinear phase mismatch by frequency mixing in gaseous media

An investigation was made of the feasibility of eliminating constraints imposed by nonlinear refraction on the maximum attainable conversion efficiency for third harmonic generation (THG) in centrosymmetric gaseous media. A numerical analysis of reduced equations showed that if cw pump radiation is focused beyond the nonlinear medium, the THG efficiency may reach values close to unity in spite of appreciable iniiomogeneous nonlinear refraction. Dependences of the conversion efficiency on the degree of focusing are given for optimum values of the linear phase mismatch for cw and pulsed radiation.