Tuning and wideband intensity modulation of noncollinear quasi‐phase‐matched second‐harmonic generation using pockels effect

Abstract

AbstractThe difficulty in highly efficient quasi‐phase‐matched second‐harmonic generation (QPM‐SHG) using periodic nonlinear structures is the strictness of the allowance of the period length or the fundamental wavelength in the quasi‐phase matched condition. As a result of these difficulties, the increase of the allowance and the easy fine‐tuning of quasi‐phase matching are very important. In this paper, the fine‐tuning of the quasi‐phase‐matched condition in bulk noncollinear (two‐dimensional) QPM‐SHG by adjusting the angle of incidence of the fundamental wave and by using the Pockels effects by the applied electric field is proposed and its properties are investigated theoretically. For wavelength variations of the fundamental wave, relaxed allowance by automatic readjustment of the angle of incidence using angular dispersions of a diffraction grating is also proposed. The relaxation is adopted in light‐intensity modulation of bulk‐type noncollinear QPM‐SHG, which is achieved by variations in phase‐matched condition by electro‐optic effect. Because nonlinear material, periodic domain inverted LiNbO3 is assumed and tuning, relaxation, and modulation characteristics are investigated through numerical simulations. As a result, it is shown that rapid tuning can easily be achieved and the proposed wide wavelength‐band light intensity modulator is expected to realize applications in optical disks, etc.