Total Blooming Effect in Active Elements of Gigawatt Terahertz Compressors

Prospective three-mirror quasi-optical compressors with laser-driven switching open the way to reach gigawatt pulsed power in terahertz band. The compressor uses a Gaussian beam that can pass through the active element without significant reflection and loss at the stage of pumping. Such blooming of the active element can be provided with an optical interference minimum and/or the Brewster effect. Reaching gigawatt power level faces a challenge of minimizing power losses inside the compressor, when even the difference between a Gaussian beam and a plane wave really matters. A novel approach of using the wave equation instead of the parabolic equation to solve the problem of a Gaussian beam propagation through an arbitrary stratified media with a complex permittivity helps us to avoid artifacts of nonzero electric field divergence. Using an advanced Fourier transformation based numerical model of integration in a wave vector space with an algorithm of lattice truncation, the study estimates and reveals a significant difference between a plane wave and a corresponding Gaussian beam that might be visible and confirmed in the near future experiments.