太赫兹波能被生物组织中的水强烈吸收, 能与生物组织中生物大分子和这些分子间的弱相互作用产生共振, 因而太赫兹波在生物医学中有许多潜在的应用. 尽管单个太赫兹光子能量很低, 对生物组织没有电离损伤作用, 但是随着强度增大, 太赫兹波会对生物细胞和组织产生一系列生物效应. 由于太赫兹波参数和受辐照生物材料等辐照条件不同, 将导致不同的生物学效应, 包括以热效应为主和以非热效应为主导致的生物学效应. 本文讨论了这两种效应的物理机理, 介绍了适合用于生物效应研究的现今主要的强太赫兹辐射源种类, 综述了典型的太赫兹波的生物效应具体表现和已有的研究进展, 展望了太赫兹波生物效应的潜在应用以及面临的挑战.

Terahertz time-domain spectroscopy (THz-TDS) is an effective coherent detection technique for deeply understanding the structures and functions of biomolecules. However, generally not full information in the whole THz range can be obtained due to the limited detection bandwidth (usually less than 5 THz) of the traditional THz-TDS systems. In this paper, effective THz absorption spectra in 0.5–10 THz range of five typical nucleobases of DNA/RNA are characterized with a super broadband THz detection technique, called the air-biased- coherent-detection (THz-ABCD) technique. Few unexpected characteristic absorption peaks appeared in the low-frequency region and meanwhile a series of anticipated characteristic absorption peaks are found in the high-frequency region. The fingerprint spectra of these nucleobases are helpful for further analysis on the vibration and twisting behavior of hydrogen bonds, van der Waals and electrostatic forces etc. between and within DNA/RNA biomolecules.

Terahertz (THz) radiation from a plasma filament array generated by focusing two-color laser pulses into the ambient air with a microlens array combining a lens is investigated. We observed a linear dependence of far-field collected THz radiation on the number of filaments and separated THz bunches that are less than 1 mm in diameter. These results indicate that the individual plasma filaments contribute incoherently to the entire THz output, which is demonstrated further with our simulation. Furthermore, the dependence of THz output on laser energy shows that the total energy of the THz beam array has not yet reached its saturation point under the conditions of current pump laser energy in our lab, indicating that it is still possible to further improve the THz output by further increasing the pump laser energy. This THz beam array may possibly be used in micro- or sub-millimeter multi-samples for THz imaging or as a stimuli array source for more scientific research in the future.

Angular distribution of protons is measured from ethanol droplet spray irradiated by linearly polarized $150\mathrm{fs}$ laser pulses at an intensity of $1.1\times {10}^{16}\mathrm{W}∕{\mathrm{cm}}^2$. Fast protons (with energies $>16\mathrm{keV}$) with an anisotropic distribution can be observed only in or near the polarization plane of the laser fields, while the slow protons (with energies $\leqq 16\mathrm{keV}$) emit with nearly an isotropic distribution. Two-dimensional particle-in-cell simulations suggest that three groups of protons originate from different acceleration regimes in the laser-droplet interaction. The first group with the highest energies is accelerated backwards by the anisotropic charge-separation field near the front surface (laser-droplet interaction side) due to the resonance absorption; the second group (forward emission) is generated by the target-normal sheath acceleration mechanism; and the third group, with the lowest energies, is accelerated by the hydrodynamic expansion of the droplet plasmas.

Van der Waals heterojunctions based on two-dimensional (2D) materials hold great potential applications in photodetectors. Using the density functional theory (DFT) method, the structures, electronic and optical properties of van der Waals WSe₂/Si₂H heterojunction are investigated. 1.32 eV of indirect bandgap is calculated from the WSe₂/Si₂H heterojunction, which is 0.3 eV and 0.1 eV smaller than those of its monolayer WSe₂ and Si₂H. This contributes to the photocarrier generations, and the Type-II heterojunction also benefits to the separation of the photogenerated electron and hole pairs. A significant hole mobility 1.05 × 10⁴ cm² V⁻¹ s⁻¹ of the heterojunction along the y-direction is obtained. Moreover, a high Ultraviolet light (UV) absorption coefficient is presented in the heterojunction. The heterojunction transforms to Type-I under a vertical electric field, with the bandgap, orientation and amount of transfer electrons modulated sufficiently. As a result, the optical absorption coefficient of the heterojunction is also improved significantly, leading to the red-shift of the absorption spectrum. These excellent properties address the WSe₂/Si₂H heterojunction one of the good candidates for UV detectors.