THz generation under excitation by ultrashort optical pulses in ordered arrays of GaAs nanowires is reported. It was found that the efficiency of THz radiation generation increases due to the resonant leaky mode excitation in nanowires. The maximum value of the THz field is achieved when the distance between the nanowires is of the order of the wavelength of exciting light.

Diabetes mellitus is a disease caused by the deficit or reduced efficiency of endogenous insulin resulting in blood sugar imbalance.¹ The development of diabetes is associated with impairments in the carbohydrate, protein, and lipid metabolism. It is almost always accompanied by a significant increase of the blood concentrations of glucose, corticosteroid hormones, and some other metabolites.¹ Protein glycation is a non-enzymatic reaction between the carbonyl groups of monosaccharides (e.g., glucose and fructose) and amino groups of proteins (e.g., albumin). Glycation initiates a cascade of protein modifications resulting in the loss of both secondary and tertiary protein structures.² Currently, the following tests are used in clinical practice to diagnose diabetes mellitus and monitor patients, for example, determining the level of glucose in venous blood plasma by the enzyme method or in capillary blood by an electrochemical method, as well as determining the level of glycated hemoglobin in whole venous blood by liquid chromatography.^3,4 All these methods require not only expensive equipment, but also reagents for their implementation. In addition, some studies can only be performed with fresh blood that cannot be stored for a long time. However, to determine some parameters, blood can be stored for a long time, but bulky freezers are required to store it. The development of methods for determining blood parameters and for storing biological samples will reduce the cost of performing diagnostic tests.^3,4

The paper presents the results of experimental studies of the generation of terahertz radiation in periodic arrays of GaAs nanowires via excitation by ultrashort optical pulses. It is found that the generation of THz radiation exhibits resonant behavior due to the resonant excitation of cylindrical modes in the nanowires. At the optimal geometric parameters of the nanowire array, the generation efficiency is found to be higher than that for bulk p-InAs, which is one of the most effective coherent terahertz emitters.

Results are reported of an experimental study of the scattering and near-field interaction of a terahertz electromagnetic field with graphene ribbons near the metallic probe of an atomic-force microscope. It is shown that the near-field terahertz scattering in ribbons is enhanced in comparison with that in the case of an unstructured graphene. Resonance peaks at 0.2–1.6 THz appear in the spectra of terahertz radiation scattering on graphene ribbons in the presence of the probe, which is possibly due to the interaction of the radiation with plasmons in the ribbons.