Terahertz Cherenkov radiation from a tightly focused ultrashort laser pulse in an electro-optic medium

An Improvement of the Cherenkov THz Generation Scheme Using Convex Silicon Prism-Lens Adapters

“…The direction of the polar angle variation change approximately near the a/R value of lens #3. In the previous paper [31], the crystal absorption at the THz fre-…”

“…First of all, let us compare the results of the numerical simulation with the results obtained in the previous work [31], where the same theoretical approach was described in detail and demonstrated using the example of several calculated distributions. The differences between these angular distributions and the ones presented here in Figures 3b and 4 are explained by the differences in the input parameters used under the numerical simulations.…”

“…Modeling of the spatial field distribution outside a Si prism with a flat output surface was performed in [25], based on the direct solution of Maxwell's equations in spatial variables [25,26,30,31]. However, this method has not been applied to obtain the detailed angular distribution of THz radiation even from a flat prism, not to mention that it is too difficult to use it in the case of a Si prism with a curved output surface.…”

Prism Couplers with Convex Output Surfaces for Nonlinear Cherenkov Terahertz Generation

“…Fundamentally, the high angular divergence takes place due to rather small dimensions of the pumped part of the nonlinear sample in comparison with the THz wavelengths. The divergence of the initially generated beam is noticeable, first of all, in the azimuthal angle, being determined by a limited cross-section of the laser beam [20]. As a result, the part of THz radiation generated with the high transverse phase mismatch is not negligible in comparison with the part generated in phase-matched directions.…”

On-Chip Time-Domain Terahertz Spectroscopy of Superconducting Films below the Diffraction Limit

“…The switch board is fabricated on a 50 μm thick cyclo-olefin polymer (COP) substrate. High transparency, low permeability, and a nearly temperature and frequency-independent optical index of ≈1.52 at THz frequencies ensure minimal pulse broadening. − The thin substrate and comparatively small dielectric constant substrate mitigate the f 3 -dependent Cerenkov radiation loss that often dominates on-chip THz propagation. ,,− In addition, the local dielectric environment of thin COP substrates does not support unbound leaky-wave modes (see Supporting Information).…”