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.

Significance: The creation of fundamentally new approaches to storing various biomaterial and estimation parameters, without irreversible loss of any biomaterial, is a pressing challenge in clinical practice. We present a technology for studying samples of diabetic and non-diabetic human blood plasma in the terahertz (THz) frequency range. Aim: The main idea of our study is to propose a method for diagnosis and storing the samples of diabetic and non-diabetic human blood plasma and to study these samples in the THz frequency range. Approach: Venous blood from patients with type 2 diabetes mellitus and conditionally healthy participants was collected. To limit the impact of water in the THz spectra, lyophilization of liquid samples and their pressing into a pellet were performed. These pellets were analyzed using THz time-domain spectroscopy. The differentiation between the THz spectral data was conducted using multivariate statistics to classify non-diabetic and diabetic groups' spectra. Results: We present the density-normalized absorption and refractive index for diabetic and nondiabetic pellets in the range 0.2 to 1.4 THz. Over the entire THz frequency range, the normalized index of refraction of diabetes pellets exceeds this indicator of non-diabetic pellet on average by 9% to 12%. The non-diabetic and diabetic groups of the THz spectra are spatially separated in the principal component space. Conclusion: We illustrate the potential ability in clinical medicine to construct a predictive rule by supervised learning algorithms after collecting enough experimental data.

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The results of investigation of electronic transport in GaAs nanowires (NWs), which were grown by MBE and MOCVD on n-type GaAs(111) substrates are presented. The time-resolved dynamics of photocarriers were studied by opticalpump terahertz generation-probe time-domain spectroscopy. The dynamics of THz generation for different levels of excitation for the GaAs NWs grown by MBE can be explained by separation of photoinduced carriers in the contact field with subsequent screening of the contact field and with non-saturable carrier recombination. The dynamics of THz generation for the GaAs NWs grown by MOCVD is due to the growth of the mobility of carriers as they are being grabbed to the non-radiative centres and as a consequence of carrier retrapping. The shift of THz pulse is connected with the changes of a phase in transmission and reflection THz pulse through the border between the absorbing and non-absorbing medium.