LAUSR

Abstract We report a scheme to generate radially polarized THz radiation by frequency difference of Hermite Cosh Gaussian lasers in hot electron, collisional and density modulated plasma. The effect of laser (spatial field distribution) and plasma parameters (plasma density structure, electron-neutral collisions and electron temperature) on emitted THz field profile is investigated. We found that THz field profile varies with spatial intensity profile of pump lasers. The THz amplitude increases with the pump laser intensity gradient. Our investigations show that electron collisions attenuate the THz amplitude without affecting the THz field profile. The highest THz field and conversion efficiency are obtained at resonance condition i.e. ω 1 − ω 2 ≈ ω p . Off-resonant excitation of THz radiation is also observed with less THz amplitude. Our investigations also reveal that the value of THz- fieldpeak and efficiency increase monotonically with electron thermal velocity (electron temperature). A high THz field (~ GV/m) and conversion efficiency ~ 0.08 can be obtained for optimized pump laser and plasma parameters.