Excitation Mode-Dependent Terahertz Radiation Generation From a Subwavelength Si–SiO2–LiNbO3–polymer–Si planar Waveguide

Optical rectification is investigated in an Si-SiO ₂ -LiNbO ₃ -polymer-Si planar waveguiding arrangement that generates and emits terahertz (THz) radiation as Cherenkov waves. Each mode supported by the waveguide (i.e., the TE ₀ , TE ₁ , and TE ₂ mode) generates a THz electric field pulse that is emitted at a distinct Cherenkov angle and contains frequencies up to ~3 THz. This waveguiding platform automatically satisfies the phase-matching condition via Cherenkov emission and permits subwavelength confinement of the excitation pulse.