In the latest scientific development, a team of scientists from the United States and South Korea has successfully developed a new type of terahertz nanoresonator, the annular nanoslit array. This research result not only solves the problem of insufficient spectral resolution in the terahertz band, but is also expected to have a far-reaching impact in the fields of medical imaging, non-destructive testing and safety inspection.
For a long time, the development of terahertz technology has been limited by its low spectral resolution and field enhancement effect. However, the research team has managed to break this bottleneck through innovative design and advanced manufacturing technology. Using a reverse engineering approach, they created a ring-shaped nanoslit array consisting of two nanostitched structures that enable efficient terahertz absorption and transmission when the transverse electric field is perpendicular to the nanoslit.
Schematic diagram of (a) terahertz nanogap ring and (b) simplified two nanogaps calculated by mode unfolding method In order to verify the effectiveness of their design, the researchers prepared gold films with nanocrevice structures using atomic layer etching technology and tested them with terahertz time-domain spectroscopy. The experimental results show that under the optimized nanocrevice structure, the field enhancement of terahertz waves can reach an astonishing 30,000-fold, which is nearly two orders of magnitude higher than that of traditional metal nanopore arrays.
Graphical summary. In addition, the research team also used the finite element method to simulate the electromagnetic field distribution of the nanocrevice structure and compared it with the experimental data. These numerical results are in good agreement with the experimental data, which further confirms the excellent performance of the new terahertz nanoresonator.
Schematic diagram of THZ TDS (B) Measurements with terahertz time-domain spectroscopy (THZ TDS) using a silicon substrate as a reference (black line) using the THZ timeline of the optimal nanogap loop array (red line) for THZ TDS. (c) After the Fourier transform of the timetrace in (b), the propagation amplitude of the optimal nanogap ring array can be converted into field enhancement by vector diffraction theory3