Terahertz Radiation Generation from Self-Focused Amplitude Modulated Gaussian Pulse in Non-Uniform Plasma Channel

This paper presents an analytical investigation of terahertz generation by self-focused amplitude modulated Gaussian laser beam at modulation frequency in non-uniform plasma channel. Due to intensity variations transverse to the propagating laser, a ponderomotive is generated. Attempts have been made to derive ponderomotive force, which generates transient transverse nonlinear current. The analytical expression for beam width parameter and amplitude of THz radiation have been derived. The self-focusing of amplitude modulated Gaussian laser beam in non-uniform channel and its effect on generated THz amplitude have been studied. It is observed that increase in the value of non-uniformity, self-focusing enhances and shifts towards lower value of propagation distance which further enhance the THz amplitude. In this study, we obtained a normalized power of the order of 10−4times the original power supplied by the laser beam by self-focusing the laser beam.