TRANSMISSION OF TERAHERTZ RADIATION THROUGH ONE-DIMENSIONAL WIRE GRATINGS AT DIFFERENT ANGLES OF INCIDENCE

Abstract

Purpose: One-dimensional wire diffraction gratings, usually being mounted on ring frames, are often used in quasi-optical instruments under the construction of functional devices of different usage. Such gratings have been thoroughly studied theoretically and experimentally at the millimeter wavelengths, where they are most widely used and realized in various constructions of instruments and systems. However, a number of design and technological features of such gratings, connected with making the polarizing devices cannot be always taken into account in theoretical models that requires additional experiments. This problem is especially relevant in the terahertz range, where there is a lack of experimental data. This work aims at experimental studying the properties of one-dimensional wire gratings in the terahertz range at different angles of incidence of electromagnetic waves and for different adjustment conditions, as well as practical recommendations concerning the measurement technique and the creation of various polarizing devices. Design/Methodology/Approach: A measuring device has been developed and manufactured, in which a gas-discharge HCN laser (at the wavelength of 337 mm) is used as a radiation source. The study of one-dimensional wire gratings of two types was carried out: grating No. 1 (conductor diameter 70 μm, period 400 mm) and grating No. 2 (conductor diameter 50 μm, period 200 μm). The gratings were installed on a rotary stand. The stepper motor provided rotation within ±90°. Measurements were made automatically with a 0.35° step. The coefficient of laser radiation transmission through the grating was investigated depending on the angle of incidence and the adjustment accuracy. Findings: Analysis of the obtained data shows that the experimental results correlate with the theoretical data. Moreover, the experimental data more fully characterize the properties of the gratings, taking into account their design and technological features, which are very difficult to take into account theoretically. The resonance maxima in the experimental dependences of the transmitted power on the angle of incidence coincide with the calculated data that makes it possible to develop a number of new measuring techniques. Recommendations are given for improving the measurement accuracy and for the practical use of the obtained results. Conclusions: The obtained experimental results allow taking into account some additional features of the diffraction gratings, as well as improving the measurement technique. This is useful for the development of new devices in the terahertz range.

Keywords

• wire grating
• terahertz range
• laser
• transmission coefficient