Timophey V. Dolmatov

The novel design of a terahertz large aperture photoconductive antenna (LAPCA) is reported. It features a longitudinal orientation of the bias electric field within the photoconductive substrate, and has the advantage of a small interelectrode gap, resulting in a higher field for the same applied voltage. The proposed LAPCA configuration has been tested with a nitrogen-doped (∼10 ppm) synthetic monocrystalline diamond, which is a promising material for high-intensity and high-power terahertz sources. Two antennas with different high-voltage electrode realizations were assembled, pumped by a 400 nm femtosecond laser, and tested for THz emitter function. The experimental data are found to be in good correlation with the numerical simulation results. The performance of antennas with the conventional transverse E-field configuration and the novel longitudinal configuration is compared and discussed.

A relatively simple fiber sensor system for high-power electromagnetic field measurements is presented. The system utilizes an all-dielectric fiber tip sensor head with CdTe electro optic (EO) crystal as an electric field transducer. The fiber sensor of small size converts electric field strength into modulation of light power. The rise time of the EO sensor is measured and evaluated theoretically. The system can be used for ultra-wideband high-power electric field measurements.

An electro-optical system is developed for measuring low field strengths (100 V cm⁻¹) of ultra-wideband electromagnetic pulses using the DAST crystal. The electric field strength is measured and the spectral composition is calculated for the radiation of the experimental ultra-wideband electromagnetic pulse oscillator.

Powerful picosecond UV pulses at a wavelength of 193nm are produced using a Nd:YAG laser radiating at a wavelength of 193nm with subsequent nonlinear transformations of the radiation and amplification in an excimer gain medium to an energy of 10 mJ.

A photoemission source of directional pulsed wideband electromagnetic radiation in the microwave region is developed, and the time profile of the generated pulse is investigated. The source is a vacuum photodiode of a parabolic shape in which a Cherenkov radiation pulse is formed by an electron current wave excited by an incident laser pulse and propagating along the surface of the anode mesh with a phase velocity higher than the speed of light.