RESUMEN
We present a holographic detection module to measure the spatially resolved distribution of pulsed terahertz field in a single scan by a motorized translation stage, responsible for the time delay. All mounts of the optical elements of the module are easily reproduced by 3D printing and attached to the optical cage system. The latter greatly simplifies the measurement procedure, allowing the experimenter to move and adjust the detection system as a single device. The developed mounts are made universal and can be used in other setups. We have made 3D models available as open-source hardware. The module is based on an electro-optical detection scheme with wide-aperture ZnTe crystal, crossed polarizers, and a matrix photodetector. The validation of its operability was performed with two experiments to measure the spatial distribution of the unperturbed field from the generator and the vortex field formed by the spiral phase plate. Optical vortices with multiple topological charges of 2-4 were detected on spectral components in the range from 0.3 to 1.1 THz. In addition, we have detailed the alignment process of terahertz imaging systems.
RESUMEN
Speckle patterns can be very promising for many applications due to their unique properties. This paper presents the possibility of numerically and experimentally formation of speckle patterns using broadband THz radiation. Strong dependence of the statistical parameters of speckles, such as size and sharpness on the parameters of the diffuser are demonstrated: the correlation length and the mean square deviation of the phase surface inhomogeneity. As the surface correlation length is increasing, the speckle size also increases and its sharpness goes down. Alternatively, the magnification of the standard deviation of the surface height leads to the speckle size diminishing and growth of the speckle sharpness. The dimensions of the experimentally formed speckles correspond to the results of numerical simulation. The possibility of utilizing formed speckle patterns for the implementation of the ghost imaging technique has been demonstrated by methods of numerical modeling.
RESUMEN
Time-resolved terahertz spectroscopy has become a common method both for fundamental and applied studies focused on improving the quality of human life. However, the issue of finding materials applicable in these systems is still relevant. One of the appropriate solution is 2D materials. Here, we demonstrate the transmission properties of unique graphene-based structures with iron trichloride FeCl3 dopant on glass, sapphire and Kapton polyimide film substrates that previously were not investigated in the framework of the above-described problems in near infrared and THz ranges. We also show properties of a thin tungsten disulfide WS2 film fabricated from liquid crystal solutions transferred to a polyimide and polyethylene terephthalate substrates. The introduction of impurities, the selection of structural dimensions and the use of an appropriate substrate for modified 2D layered materials allow to control the transmission of samples for both the terahertz and infrared ranges, which can be used for creation of effective modulators and components for THz spectroscopy systems.