The momentum relaxation time of a photoexcited graphene in the THz frequency range has been studied by using terabertz time domain spectroscopy under optical pumping at room temperature. It is found that the momentum ...The momentum relaxation time of a photoexcited graphene in the THz frequency range has been studied by using terabertz time domain spectroscopy under optical pumping at room temperature. It is found that the momentum relaxation time of the graphene as a function of the optical pumping intensity exhibits a threshold behavior. The features of the momentum relaxation time as a function of the optical pumping intensity are also investigated. The results are useful for understanding the basic underlying physics of graphene scattering as well as finding the possible applications in carbon- based electronics.展开更多
The absorption coefficient of magnesium-doped near-stoichiometric lithium niobate crystal is measured by terahertz time-domain spectroscopy in a frequency range of 0.2 THz^0.9 THz at room temperature. The absorption c...The absorption coefficient of magnesium-doped near-stoichiometric lithium niobate crystal is measured by terahertz time-domain spectroscopy in a frequency range of 0.2 THz^0.9 THz at room temperature. The absorption coefficient is modulated by external optical pump fields. Experimental results show that the absorption coefficient of near-SLN：Mg crystal is approximately in a range of 22 cm- 1_35 cm- 1 in a frequency range of 0.2 THz-0.9 THz and tunable up to nearly 15%. Further theoretical analysis reveals that the variation of absorption coefficient is related to the number of light-induced carriers, domain reversal process, and OH- absorption in this crystal.展开更多
This paper presents a set of equations describing the terahertz generation and electro-optic detection based on optical rectification in zincblende crystals. The dependence of terahertz emission efficiency on the pola...This paper presents a set of equations describing the terahertz generation and electro-optic detection based on optical rectification in zincblende crystals. The dependence of terahertz emission efficiency on the polarization of incident beam and crystal-orientation is discussed. For the experimental setup with a transceiver which transmits and detects terahertz radiation in the same crystal, we have demonstrated the optimal combination of both parameters above to optimize the working efficiency. Equations supplied in this paper are valid for zincblende crystals with arbitrary crystal- orientation and every possible polarization of an incident beam, which are of great significance for the optimization of a system.展开更多
The dielectric properties of near-stoichiometric LiNbO3：Fe and LiNbO3：Ce single crystals have been investigated using terahertz time domain spectroscopy in a frequency range of 0.71.6 THz at room temperature. When c...The dielectric properties of near-stoichiometric LiNbO3：Fe and LiNbO3：Ce single crystals have been investigated using terahertz time domain spectroscopy in a frequency range of 0.71.6 THz at room temperature. When coupled with an applied external optical field, obvious photorefractive effects were observed, resulting in a modulation of the complex dielectric constant for the crystals. The variation in refractive index, ｜△n｜, had a linear relationship with the applied light intensity, accompanied by a step-like decrease at high intensity. The findings were attributed to the internal space charge field of the photorefraction and the light-induced domain reversal in the crystals.展开更多
基金supported by the National Natural Science Foundation of China (Grants Nos. 10974063 and 61177095)the Hubei Natural Science Foundation, China (Grant Nos. 2010CDA001 and 2012FFA074)+2 种基金the Research Foundation of Huazhong University of Science and Technology, China (Grant Nos. 01-09-230904 and 02-16-230008)the PhD Program Foundation of Ministry of Education of China (Grant No. 20100142110042)the Fundamental Research Funds for the Central Universities, China (Grant Nos. HUST: 2010MS041 and 2011TS001)
文摘The momentum relaxation time of a photoexcited graphene in the THz frequency range has been studied by using terabertz time domain spectroscopy under optical pumping at room temperature. It is found that the momentum relaxation time of the graphene as a function of the optical pumping intensity exhibits a threshold behavior. The features of the momentum relaxation time as a function of the optical pumping intensity are also investigated. The results are useful for understanding the basic underlying physics of graphene scattering as well as finding the possible applications in carbon- based electronics.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10974063,61205096,and 61177095)the Natural Science Foundation of Hubei Province,China (Grant Nos.02-16-230008,2010CDA001,and 2012FFA074)+2 种基金the Research Foundation of Huazhong University of Science and Technology,China (Grant No.01-09-230904)the Ph.D.Program Foundation of Ministry of Education of China (Grant No.20100142110042)the Fundamental Research Funds for the Central Universities,China (Grant Nos.2010MS041 and 2011TS001)
文摘The absorption coefficient of magnesium-doped near-stoichiometric lithium niobate crystal is measured by terahertz time-domain spectroscopy in a frequency range of 0.2 THz^0.9 THz at room temperature. The absorption coefficient is modulated by external optical pump fields. Experimental results show that the absorption coefficient of near-SLN：Mg crystal is approximately in a range of 22 cm- 1_35 cm- 1 in a frequency range of 0.2 THz-0.9 THz and tunable up to nearly 15%. Further theoretical analysis reveals that the variation of absorption coefficient is related to the number of light-induced carriers, domain reversal process, and OH- absorption in this crystal.
基金supported by the National Natural Science Foundation of China (Grant No. 10974063)the Natural Science Foundation of Hubei Province of China (Grant No. 2010CDA001)+2 种基金Ph. D. Program Foundation of the Ministry of Education of China (Grant No. 20100142110042)the Fundamental Research Funds for the Central Universities (Grant No. HUST:2010MS041)the National "973" Project (Grant No. 2007CB310403)
文摘This paper presents a set of equations describing the terahertz generation and electro-optic detection based on optical rectification in zincblende crystals. The dependence of terahertz emission efficiency on the polarization of incident beam and crystal-orientation is discussed. For the experimental setup with a transceiver which transmits and detects terahertz radiation in the same crystal, we have demonstrated the optimal combination of both parameters above to optimize the working efficiency. Equations supplied in this paper are valid for zincblende crystals with arbitrary crystal- orientation and every possible polarization of an incident beam, which are of great significance for the optimization of a system.
基金Project supported by the National Natural Science Foundation of China(Grant No.10974063)the Research Foundation of Wuhan National Laboratory,China(Grant No.P080008)the National Basic Research Program of China(Grant No.2007CB310403)
文摘The dielectric properties of near-stoichiometric LiNbO3：Fe and LiNbO3：Ce single crystals have been investigated using terahertz time domain spectroscopy in a frequency range of 0.71.6 THz at room temperature. When coupled with an applied external optical field, obvious photorefractive effects were observed, resulting in a modulation of the complex dielectric constant for the crystals. The variation in refractive index, ｜△n｜, had a linear relationship with the applied light intensity, accompanied by a step-like decrease at high intensity. The findings were attributed to the internal space charge field of the photorefraction and the light-induced domain reversal in the crystals.
