Terahertz time-domain spectroscopy (THz-TDS) system and the related technology and its applications in capital normal university (CNU) are presented. Most often used THz-TDS system as a spectroscopic measurement setup in our lab is introduced in detail, including THz radiation source, THz detection method and its measurement and control system. THz spectra of some materials measured in CNU is summarized and discussed. These materials include but not limited to two kinds of typical matter - the illegal drugs and the explosives, the biological macro-molecules, the cosmetics and the fine chemical materials, the edible pigments and the food additives, the homocysteic acid and related compounds, the heavy ions in soil, the Chinese medicines, the tobacco and crops, the oil and chemical products, the carbon nanotubes, the superconductors, and various semiconductors and their heterojunctions, are presented. THz emission from InAs and InN semiconductor surface are compared. THz spectral investigation of metallic mesh structures is summarized. Finally, an outlook of THz spectroscopic application on metamaterials characteristic is presented briefly.

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We theoretically demonstrate a clear and straightforward approach, which just relies on a simple DC spatially gradient electric potential, for robustly generating bright chirp-free attosecond pulses of electromagnetic radiation throughout the soft X-ray region of the spectrum with pulse durations in the single-digit attosecond range.

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An ideal freestanding graphene in air is centrosymmetric in three dimensions, and its optical second harmonic generation is inhibited. However, we found strong second harmonic generation from suspended single-layer graphene, and attributed this observation to curved sheet in the long range.

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A numerical study of maximum extractable energy for Ytterbium-doped high-power pulsed fiber laser amplifiers is presented. The influence of stimulated Raman scattering on amplified processes is considered. The simulation results show the criterions of seed energy and width to suppress Stokes waves. Optimized experimental parameters are suggested in this contribution.

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A 800 nm Ti: sapphire laser is transferred to a transform limit 400 nm by SHG through the BBO crystal. We passed the 400 nm light through a set of fused silica plates to generate a broadband continuum ranging from 320 nm to 480 nm by four-wave mixing and filamentation.

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