Recently, the generation of near-single-cycle terahertz pulses with 10μJ energy was demonstrated by optical rectification of ultrashort laser pulses with tilted pulse front in LiNbO3. Here, an optimized imaging setup is proposed for the creation of the tilted pulse front inside the LiNbO3 crystal. Furthermore, a compact setup is proposed which creates the tilted pulse front without imaging, where there is no principal limitation on the pump spot size and, hence, on the terahertz energy. According to model calculations, application of these setups can increase the efficiency by one order of magnitude for 5mm spot size.

Hadron therapy motivates research dealing with the production of particle beams with $\sim 100\mathrm{MeV}/\text{nucleon}$ energy and relative energy fluctuation on the order of 1%. Laser-driven accelerators produce ion beams with only tens of $\mathrm{MeV}/\text{nucleon}$ energy and an extremely broad spectra. Here, a novel method is proposed for postacceleration and monochromatization of particles, leaving the laser-driven accelerator, by using intense THz pulses. It is based on further developing the idea of using the evanescent field of electromagnetic waves between a pair of dielectric crystals. Simple model calculations show that the energy of a proton bunch can be increased from 40 to 56 MeV in five stages and its initially broad energy distribution can be significantly narrowed down.

A hybrid-type terahertz pulse source is proposed for high energy terahertz pulse generation. It is the combination of the conventional tilted-pulse-front setup and a transmission stair-step echelon-faced nonlinear crystal with a period falling in the hundred-micrometer range. The most important advantage of the setup is the possibility of using plane parallel nonlinear optical crystal for producing good-quality, symmetric terahertz beam. Another advantage of the proposed setup is the significant reduction of imaging errors, which is important in the case of wide pump beams that are used in high energy experiments. A one dimensional model was developed for determining the terahertz generation efficiency, and it was used for quantitative comparison between the proposed new hybrid setup and previously introduced terahertz sources. With lithium niobate nonlinear material, calculations predict an approximately ten-fold increase in the efficiency of the presently described hybrid terahertz pulse source with respect to that of the earlier proposed setup, which utilizes a reflective stair-step echelon and a prism shaped nonlinear optical crystal. By using pump pulses of 50 mJ pulse energy, 500 fs pulse length and 8 mm beam spot radius, approximately 1% conversion efficiency and 0.5 mJ terahertz pulse energy can be reached with the newly proposed setup.

Conception of a hybrid type tilted-pulse-front pumping scheme for the generation of high-energy terahertz pulses is presented. The proposed setup is the combination of the conventional setup containing imaging optics and the contact grating. The solution was developed for nonlinear materials requiring large pulse-front-tilt angle, like LiNbO₃. Due to the creation of the pulse-front-tilt in two steps the limitations of imaging errors can be significantly reduced. Furthermore the necessary grating constant of the contact grating can be larger compared to the simple contact grating scheme making possible the fabrication of the grating profile with significantly higher precision. A detailed optimization procedure with respect to the diffraction efficiency on the contact grating is given for LiNbO₃. Instructions are also given how to construct the geometry of the setup in order to minimize imaging errors. Examples are given for LiNbO₃ based practically realizable, optimized schemes with reduced imaging errors and high diffraction efficiency on the contact grating.