High-Power Tunable Laser Driven THz Generation in Corrugated Plasma Waveguides

摘要

The excitation of THz radiation by the interaction of an ultra short laserpulse with the modes of a miniature corrugated plasma waveguide is considered.The axially corrugated waveguide supports the electromagnetic (EM) modes withappropriate polarization and subluminal phase velocities that can be phasematched to the ponderomotive potential associated with laser pulse, makingsignificant THz generation possible. This process is studied via full formatParticle-in-Cell (PIC) simulations that, for the first time, model thenonlinear dynamics of the plasma and the self-consistent evolution of the laserpulse in the case where the laser pulse energy is entirely depleted. It isfound that the generated THz is characterized by lateral emission from thechannel, with a spectrum that may be narrow or broad depending on the laserintensity. A range of realistic laser pulse and plasma parameters is consideredwith the goal of maximizing the conversion efficiency of optical energy to THzradiation. As an example, a fixed drive pulse (0.55 J) with a spot size of 15$\mu m$ and duration of 15 $fs$ produces 37.8 mJ of THz radiation in a 1.5 cmcorrugated plasma waveguide with an on axis average density of$1.4\times10^{18} cm^{-3}$.