Cascaded terahertz-wave generation efficiency in excess of the Manley–Rowe limit using a cavity phase-matched optical parametric oscillator

We describe a scheme for efficient terahertz (THz) generation using a cascaded optical parametric oscillator using a GaP sheet cavity. By choosing an appropriate pump wavelength and cavity design, the cascading process contributes to efficient THz-wave generation, resulting in a high output peak power of 1.8 MW and a high photon conversion efficiency of 1.086 at 3 THz. This exceeds the Manley–Rowe limit, and the method described here is applicable to widely tunable and high-power THz-wave generation using an optically isotropic nonlinear optical material, such as GaAs, InP, ZnTe, or GaP. Our simulated data show that high-power THz sources are possible that are suitable for the realization of nonlinear optical effects at THz frequencies.