Abstract
Terahertz electromagnetic eigenmodes of a semiconductor slab in the presence of a transverse magnetic field are analyzed and their excitation by beating of lasers is investigated. The modes are mixed transverse electric and transverse magnetic modes with finite axial components of both the electric field and the magnetic field, and phase velocities are significantly influenced by the magnetic field. Two high-intensity lasers propagating through the slab exert a beat frequency ponderomotive force on electrons that produces a nonlinear current and drives a terahertz eigenmode. The magnetic field acts as a suitable tuning parameter and enhances the terahertz power. In n-type germanium with electron density of approximately 1016 cm−3, laser intensity 1013 W/cm2 at 10-μm wavelength, and Bs≈6 T, terahertz radiation of 108 W/cm2 can be produced.