Efficient backward second-harmonic generation in quasi-phase-matched second-order nonlinear medium: a novel configuration

Summary form only given. A conventional second-order nonlinear material such as KTP or LiNbO/sub 3/ can be periodically poled to achieve second-harmonic generation (SHG). In this type of the medium, quasi-phase matching (QPM) has been achieved by spatial modulation of the second-order susceptibility such that the fundamental and second-harmonic waves can be in phase when they propagate in the same direction. The thickness of each domain is usually much larger than the wavelength of the fundamental or SH wave. Here, we present our results of investigating possibility of generating a backward SH based on a novel scheme. In this novel configuration the period of the domain structure is equal to the SH wavelength in the material. Therefore the second-order susceptibility has to be modulated spatially with the period much shorter than that achieved before.