Copper sulfate pentahydrate is investigated by terahertz time-domain spectroscopy. It is shown that the terahertz absorption coefficients are correlated with the particle size of the samples, as well as the heating ra...Copper sulfate pentahydrate is investigated by terahertz time-domain spectroscopy. It is shown that the terahertz absorption coefficients are correlated with the particle size of the samples, as well as the heating rates of the ambient temperature. Furthermore, the water molecules of copper sulfate pentahydrate can be quantitatively characterized due to the high sensitivity of the terahertz wave to water molecules. Based on such results, the status of water incorporated in mineral opal is also characterized using terahertz time-domain spectroscopy. It indicates that terahertz technology can be considered as an efficient method to detect the dehydration of minerals.展开更多
Optical operations have served as the basis of spectroscopy and imaging in terahertz regimes for a long time.Available lenses are practical tools for modulations.We fabricate a kind of biconvex lens from the natural d...Optical operations have served as the basis of spectroscopy and imaging in terahertz regimes for a long time.Available lenses are practical tools for modulations.We fabricate a kind of biconvex lens from the natural dolomite cluster.The lens works well at 0.1 THz based on the relatively high refractive index and low absorption coefficients.Compared with the lens fabricated by a dolomite stone,such a lens can focus dispersive terahertz beam efficiently in terahertz imaging systems,which indicates that natural minerals hold promising applications in terahertz optics.展开更多
The zero refractive index properties of two-dimensional photonic crystals(PCs) are studied theoretically. Three necessary conditions for PCs to mimic the zero index materials(ZIMs) are obtained. In addition, through a...The zero refractive index properties of two-dimensional photonic crystals(PCs) are studied theoretically. Three necessary conditions for PCs to mimic the zero index materials(ZIMs) are obtained. In addition, through a comparative study of the properties for two representative PC structures with different types of Dirac cones, we find that the PC with a Dirac-like cone which meets the three necessary conditions does not behave as a ZIM in some cases. Further analysis shows that its non-zero index properties originate from the flat dispersion band.These findings clarify the fundamental physical issue of which type of Dirac cone PC can mimic a real ZIM.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61805214)the Fundamental Research Funds for the Central Universities,China(Grant No.2652017142)
文摘Copper sulfate pentahydrate is investigated by terahertz time-domain spectroscopy. It is shown that the terahertz absorption coefficients are correlated with the particle size of the samples, as well as the heating rates of the ambient temperature. Furthermore, the water molecules of copper sulfate pentahydrate can be quantitatively characterized due to the high sensitivity of the terahertz wave to water molecules. Based on such results, the status of water incorporated in mineral opal is also characterized using terahertz time-domain spectroscopy. It indicates that terahertz technology can be considered as an efficient method to detect the dehydration of minerals.
基金Supported by the National Natural Science Foundation of China under Grant No 61805214the Fundamental Research Funds for the Central Universities under Grant No 2652017142
文摘Optical operations have served as the basis of spectroscopy and imaging in terahertz regimes for a long time.Available lenses are practical tools for modulations.We fabricate a kind of biconvex lens from the natural dolomite cluster.The lens works well at 0.1 THz based on the relatively high refractive index and low absorption coefficients.Compared with the lens fabricated by a dolomite stone,such a lens can focus dispersive terahertz beam efficiently in terahertz imaging systems,which indicates that natural minerals hold promising applications in terahertz optics.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11504336 and 61805214the Fundamental Research Funds for the Central Universities under Grant No 265201430
文摘The zero refractive index properties of two-dimensional photonic crystals(PCs) are studied theoretically. Three necessary conditions for PCs to mimic the zero index materials(ZIMs) are obtained. In addition, through a comparative study of the properties for two representative PC structures with different types of Dirac cones, we find that the PC with a Dirac-like cone which meets the three necessary conditions does not behave as a ZIM in some cases. Further analysis shows that its non-zero index properties originate from the flat dispersion band.These findings clarify the fundamental physical issue of which type of Dirac cone PC can mimic a real ZIM.
