In recent years, with the progress of science, more and more detection methods are being used in various fields. However, the nondestructive testing of nonmetallic materials still needs further study. In this paper, an analysis of the time domain characteristics of rubber materials using terahertz detection technology was carried out, obtaining different defect rubber material spectral characteristics as well as imaging results and data. The results show that the THz spectrum imaging technique can detect the thickness of rubber material in the 0.1 ~ 4.0 terahertz band, and the image is clear and the resolution high. Meanwhile the time domain waveform obtained is sensitive to the debonding defects of the sample rubber, is suitable for judging the overall performance of the rubber inner defect detection, and can provide the scientific basis for rubber material performance.

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Cancer is one of the leading causes of mortality worldwide. In recent years, various kinds of biosensors based on optical fiber have been proposed for detection of cancer cells due to their advantages of accurate diagnosis, small size, low cost, and flexible design parameters. In the present study, a microstructure fiber (MSF) biosensor with porous-core structures was designed to detect cancer cells using a terahertz time-domain system (TDS). The fiber characteristics of the proposed MSF were optimized by adopting a finite element numerical technique and perfectly matching layer absorption boundary conditions. The numerical results show that the proposed biosensor presented an ultrahigh sensitivity for detection of cancer cells. Under the optimal condition of 0.9 THz, the relative sensitivity of the proposed structure to breast cancer cells was as high as 99.8%. Moreover, other optical fiber parameters, such as effective material loss (EML), confinement loss (CL), numerical aperture (NA), power fraction, and effective area (Aeff), were optimal according to the reported results. The proposed structure can be easily fabricated by 3D printing and flexibly applied in the fields of biomedicine and biosensing with a terahertz (THz) waveguide.

A single-mode hollow-core anti-resonant (HC-AR) waveguide designed for low-loss terahertz (THz) wave propagation is fabricated by three-dimensional (3D) printing. Compared to similar structures reported recently, the rotating-nested semi-elliptical tubes (SETs) in the HC-AR THz waveguide cladding suppress multiple high-order modes (LP11, LP21, and LP02 modes) at the same time giving rise to enhanced single-mode transmission and low losses. Three HC-AR THz waveguides with different wall thicknesses are produced using two photosensitive resins and analyzed by THz time-domain spectroscopy (THz-TDS). The experimental results show that the electric field distributions at the output end of these waveguides have a Gaussian-like distribution reflecting that of the single mode. The smallest transmission losses determined by the ‘cut-back’ method are 0.03 cm− 1 at 0.31 THz for sample A, 0.02 cm− 1 at 0.4 THz for sample B, and 0.01 cm− 1 at 0.23 THz for sample C. The consistent experimental and simulated results reveal that the HC-AR THz waveguide has many advantages over current ones by achieving low losses and single-mode operation simultaneously.