Abstract-Study on the effects of terahertz radiation on gene networks of Escherichia coli by means of fluorescent biosensors

Danil S. Serdyukov, Tatiana N. Goryachkovskaya, Irina A. Mescheryakova, Svetlana V. Bannikova, Sergei A. Kuznetsov, Olga P. Cherkasova, Vasiliy M. Popik, and Sergey E. Peltek

General schemes of experiments with irradiating cultured-bacterial-cells samples by the NovoFEL (a) and TeraSense source (b).

https://www.osapublishing.org/boe/abstract.cfm?uri=boe-11-9-5258

Three novel fluorescent biosensors sensitive to terahertz (THz) radiation were developed via transformation of Escherichia coli (E. coli) cells with plasmids, in which a promotor of genes matA, safA, or chbB controls the expression of a fluorescent protein. The biosensors were exposed to THz radiation from two sources: a high-intensity pulsed short-wave free electron laser and a low-intensity continuous long-wave IMPATT-diode-based device. The threshold and dynamics of fluorescence were found to depend on radiation parameters and exposure time. Heat shock or chemical stress yielded the absence of fluorescence induction. The biosensors are evaluated to be suitable for studying influence of THz radiation on the activity of gene networks related with considered gene promoters.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Broadband Circular-to-Linear Polarization Conversion of Terahertz Waves Using Self-Complementary Metasurfaces

Andrey Sayanskiy, Sergei A. Kuznetsov, Daria S. Tanygina, Juan P. del Risco, Stanislav Glybovski, Juan D. Baena

https://128.84.21.199/abs/1807.07181v1

In this work, we theoretically and experimentally study the conversion from a circularly polarized plane electromagnetic wave into a linearly polarized transmitted one using anisotropic self-complementary metasurfaces. For this purpose, a metasurface design operable at sub-terahertz frequencies is proposed and investigated in the range of 230-540 GHz. The metasurface is composed of alternating complementary rectangular patches and apertures patterned in an aluminum layer deposited on a thin polypropylene film. The term \textit{self-complementary} implies that the pattern is invariant with respect to its inversion (with some translation). Our study shows that the translational symmetry of the metasurface results in unusual and useful electromagnetic properties under illumination with circularly polarized radiation beams. In particular, alongside with broadband circular-to-linear conversion, the transmitted wave exhibits a frequency independent magnitude, while its polarization angle gradually changes with frequency that paves the way for new beam-splitting applications.

Abstract-Extraordinary THz Transmission with a Small Beam Spot: The Leaky Wave Mechanism

Miguel Navarro-Cía, Víctor Pacheco-Peña, Sergei A. Kuznetsov, Miguel Beruete

http://onlinelibrary.wiley.com/doi/10.1002/adom.201701312/full

The discovery of extraordinary optical transmission (EOT) through patterned metallic foils in the late 1990s was decisive for the development of plasmonics and cleared the path to employ small apertures for a variety of interesting applications all along the electromagnetic spectrum. However, a typical drawback often found in practical EOT structures is the large size needed to obtain high transmittance peaks. Consequently, practical EOT arrays are usually illuminated using an expanded (mimicking a plane wave) beam. Here, it is shown with numerical and experimental results in the THz range that high transmittance peaks can be obtained even with a reduced illumination spot exciting a small number of holes, provided that the structure has a sufficient number of lateral holes out of the illumination spot. These results shed more light on the prominent role of leaky waves in the underlying physics of EOT and have a direct impact on potential applications.

Abstract-Selective Pyroelectric Detection of Millimetre Waves Using Ultra-Thin Metasurface Absorbers

• Sergei A. Kuznetsov
• , Andrey G. Paulish
• , Miguel Navarro-Cía
•  & Andrey V. Arzhannikov

http://www.nature.com/articles/srep21079

Sensing infrared radiation is done inexpensively with pyroelectric detectors that generate a temporary voltage when they are heated by the incident infrared radiation. Unfortunately the performance of these detectors deteriorates for longer wavelengths, leaving the detection of, for instance, millimetre-wave radiation to expensive approaches. We propose here a simple and effective method to enhance pyroelectric detection of the millimetre-wave radiation by combining a compact commercial infrared pyro-sensor with a metasurface-enabled ultra-thin absorber, which provides spectrally- and polarization-discriminated response and is 136 times thinner than the operating wavelength. It is demonstrated that, due to the small thickness and therefore the thermal capacity of the absorber, the detector keeps the high response speed and sensitivity to millimetre waves as the original infrared pyro-sensor does against the regime of infrared detection. An in-depth electromagnetic analysis of the ultra-thin resonant absorbers along with their complex characterization by a BWO-spectroscopy technique is presented. Built upon this initial study, integrated metasurface absorber pyroelectric sensors are implemented and tested experimentally, showing high sensitivity and very fast response to millimetre-wave radiation. The proposed approach paves the way for creating highly-efficient inexpensive compact sensors for spectro-polarimetric applications in the millimetre-wave and terahertz bands.