Third-harmonic generation in quasi-phase-matched χ(2) media with missing second harmonic

What we believe to be a conceptually novel scheme for third-harmonic generation in engineered quasi-phase-matched X(2) optical structures is proposed in which the fundamental-frequency field is directly converted into the third-harmonic field without the intermediate generation of the second-harmonic field. This countrintuitive scheme, which exploits the concept of adiabatic passage and the existence of a nonlinear dark state, bears a close connection to the stimulated Raman adiabatic passage technique of population transfer in atomic physics. (c) 2007 Optical Society of America.