High-efficiency terahertz generation via nonlinear mixing in magnetized capillary plasma waveguides

Abstract This study presents a novel approach for high-efficiency terahertz (THz) generation through nonlinear mixing of co-propagating lasers in magnetized capillary plasma waveguides. The introduction of a transverse static magnetic field ( B s ) enables resonant coupling with the nonlinear current driven by laser ponderomotive forces and a tailored density ripple ( n q ). Theoretical analysis demonstrates that magnetic field tuning of the electron cyclotron frequency ( ω c ) to match THz frequencies ( ω THz ) amplifies transverse nonlinear currents by a resonant factor [ 1 − ( ω c / ω ) 2 ] − 2 . The system achieves phase-matched excitation of transverse electromagnetic waves satisfying k = k 1 − k 2 − q and ω ≈ ω p (plasma frequency). Under optimal conditions ( B s = 10 5 G (10 T), n q / n 0 = 0.3 ), the conversion efficiency achieves P THz / P Laser ∼ 10 − 3 , markedly exceeding the performance of traditional optical rectification and photoconduction techniques. Power scaling exhibits quadratic dependence on density ripple amplitude ( ∝ ( n q / n 0 ) 2 ) and quartic dependence on laser intensity ( ∝ (