Narrowband terahertz source based on four-wave mixing

This paper proposes theoretically a novel terahertz source based on polarization-maintaining optical fibers. Utilizing the dual-wavelength laser as the pump source and four-wave-mixing effect in the optical fibers, a compact wide-tunable narrowband terahertz source can be constructed. The surface-emitting scheme is used to decrease the absorption loss of terahertz waves in the optical fibers. The four-wave mixing process and the phase-matching conditions are discussed through the coupled-wave theory, and the analytical expression of terahertz output power is obtained. It is shown that when the pump peak power is about 1 kW, the terahertz peak power is about 350 mW at 6 THz, and the power conversion efficiency is about 0.01%. This scheme provides a possibility to realize a high-power, comp