A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_4(KTP) crystal. The tuning range was observed intermittently from 0.96 TH...A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_4(KTP) crystal. The tuning range was observed intermittently from 0.96 THz to 1.87 THz,from 3.04 THz to 3.33 THz, from 4.17 THz to 4.48 THz, from 4.78 THz to 4.97 THz, from 5.125 THz to 5.168 THz, from5.44 THz to 5.97 THz, and from 6.74 THz to 7.01 THz. The dual-Stokes wavelengths resonance phenomena were observed in some certain tuning angle ranges. Through the theoretical analysis of the dispersion curve of the KTP crystal, the intermittent THz wave tuning range and dual-wavelength Stokes waves operation during angle tuning process were explained.The theoretical analysis was in good agreement with the experiment results. The maximum THz output voltage detected by Golay cell was 1.7 V at 5.7 THz under the pump energy of 210 mJ, corresponding to the THz wave output energy of5.47 μJ and conversion efficiency of 2.6 × 10^(-5).展开更多
BACKGROUND Hepatocellular carcinoma(HCC) is one of the most common malignant tumors worldwide, and novel methods for early/rapid diagnosis of HCC are needed.Terahertz(THz) spectroscopy is considered to have the potent...BACKGROUND Hepatocellular carcinoma(HCC) is one of the most common malignant tumors worldwide, and novel methods for early/rapid diagnosis of HCC are needed.Terahertz(THz) spectroscopy is considered to have the potential to distinguish between normal liver tissue and HCC tissue; however, there are few reports on it.We conduct this observational study to explore the feasibility of THz imaging for the diagnosis of HCC.AIM To evaluate the feasibility of THz for discriminating between HCC and normal liver tissues using fresh tissue specimens obtained from HCC patients who had undergone surgery.METHODS Normal liver tissue and HCC tissue were cryosectioned into 50 μm-thick slicesand placed on cover glass. Two adjacent tissue sections were separated subjected to histopathological examination by hematoxylin and eosin staining or THz transmission examination, and THz images were compared with pathologically mapped images. We determined the typical tumor and normal liver tissue regions by pathological examination; the corresponding areas of adjacent sections were examined by THz transmission.RESULTS The transmission rate of HCC tissue was 0.15-0.25, and the transmission rate of typical HCC tissue was about 0.2. THz transmittance in normal liver tissue is slightly higher than 0.4, but there were many influencing factors, including the degree of liver cirrhosis, fat components, ice crystals in frozen sections, and apoptosis.CONCLUSION In conclusion, this study shows that THz imaging can detect HCC tissue. Further research will yield more detailed data of the THz transmission rates of HCC tissue with different degrees of differentiation.展开更多
Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed protonexchange waveguide are numerically simulated.The effects of the finite depth,conical shape,trapezoidal shape ...Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed protonexchange waveguide are numerically simulated.The effects of the finite depth,conical shape,trapezoidal shape and hybrid shape of holes are theoretically analyzed.Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate(LiNbO_3),a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode,and useful transmission spectra with strong contrast and sharp band edges are achieved.展开更多
The dynamic tunability of a terahertz(THz) passband filter was realized by changing the Fermi energy(E_F) of graphene based on the sandwiched structure of metal-graphene-metal metamaterials(MGMs). By using plane wave ...The dynamic tunability of a terahertz(THz) passband filter was realized by changing the Fermi energy(E_F) of graphene based on the sandwiched structure of metal-graphene-metal metamaterials(MGMs). By using plane wave simulation, we demonstrated that the central frequency( f_0) of the proposed filter can shift from 5.04 THz to 5.71 THz; this shift is accompanied by a 3 dB bandwidth(? f) decrease from 1.82 THz to 0.01 THz as the EFincreases from 0 to 0.75 eV.Additionally, in order to select a suitable control equation for the proposed filter, the curves of ? f and f_0 under different graphene EFwere fitted using five different mathematical models. The fitting results demonstrate that the Dose Resp model offers accurate predictions of the change in the 3 dB bandwidth, and the Quartic model can successfully describe the variation in the center frequency of the proposed filter. Moreover, the electric field and current density analyses show that the dynamic tuning property of the proposed filter is mainly caused by the competition of two coupling effects at different graphene EF, i.e., graphene-polyimide coupling and graphene-metal coupling. This study shows that the proposed structures are promising for realizing dynamically tunable filters in innovative THz communication systems.展开更多
Based on the index-induced mode coupling between the higher-order mode in core and the fundamental mode in cladding tubes,the single-mode operation can be realized in any antiresonant fibers(ARFs)when satisfying that ...Based on the index-induced mode coupling between the higher-order mode in core and the fundamental mode in cladding tubes,the single-mode operation can be realized in any antiresonant fibers(ARFs)when satisfying that the area ratio of cladding tube and core is about 0.46:1,and this area ratio also should be modified according to the shape and the number of cladding tubes.In the ARF with nodal core boundary,the mode in core also can couple with the mode in the wall of core boundary,which can further enhance the suppression of high-order mode.Accordingly,an ARF with conjoint semi-elliptical cladding tubes realizes a loss of higher-order mode larger than 30 dB/m;simultaneously,a loss of fundamental mode loss less than 0.4 dB/m.展开更多
A compact terahertz(THz) imaging system based on complementary compressive sensing has been proposed using two single-pixel detectors. By using a mechanical spatial light modulator, sampling in the transmission and re...A compact terahertz(THz) imaging system based on complementary compressive sensing has been proposed using two single-pixel detectors. By using a mechanical spatial light modulator, sampling in the transmission and reflection orientations was achieved simultaneously, which allows imaging with negative mask values. The improvement of THz image quality and anti-noise performance has been verified experimentally compared with the traditional reconstructed image, and is in good agreement with the numerical simulation. The demonstrated imaging system, with the advantages of high imaging quality and strong anti-noise property, opens up possibilities for new applications in the THz region.展开更多
A multi-lens retroreflector with field curvature compensation was designed and used in an alignment-free distributed-cavity laser with a long working distance for resonant beam charging applications.The multi-lens des...A multi-lens retroreflector with field curvature compensation was designed and used in an alignment-free distributed-cavity laser with a long working distance for resonant beam charging applications.The multi-lens design,which makes use of off-the-shelf components,also allows a large field of view[FoV]without requirement of large element aperture.By implementing this design,an end-pumped 1063 nm Nd:GdVO4 laser could deliver over 5 W continuous-wave output power over a large range of working distances(1-5 m)and with ±30°receiver FoV under an incident diode pump power of 16.6 W.The output power fluctuation was less than 10%when moving and tilting the receiver over such a large range,without requiring any realignment of the cavity.展开更多
基金Project supported by the National Basic Research Program of China(Grant Nos.2015CB755403 and 2014CB339802)the National Key Research and Development Program of China(Grant No.2016YFC0101001)+2 种基金the National Natural Science Foundation of China(Grant Nos.61775160,61771332,and 61471257)China Postdoctoral Science Foundation(Grant No.2016M602954)Postdoctoral Science Foundation of Chongqing,China(Grant No.Xm2016021)
文摘A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_4(KTP) crystal. The tuning range was observed intermittently from 0.96 THz to 1.87 THz,from 3.04 THz to 3.33 THz, from 4.17 THz to 4.48 THz, from 4.78 THz to 4.97 THz, from 5.125 THz to 5.168 THz, from5.44 THz to 5.97 THz, and from 6.74 THz to 7.01 THz. The dual-Stokes wavelengths resonance phenomena were observed in some certain tuning angle ranges. Through the theoretical analysis of the dispersion curve of the KTP crystal, the intermittent THz wave tuning range and dual-wavelength Stokes waves operation during angle tuning process were explained.The theoretical analysis was in good agreement with the experiment results. The maximum THz output voltage detected by Golay cell was 1.7 V at 5.7 THz under the pump energy of 210 mJ, corresponding to the THz wave output energy of5.47 μJ and conversion efficiency of 2.6 × 10^(-5).
基金Supported by the National Natural Science Foundation of China under Grant Nos 60508004 and 60778043, and the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20060055024.
文摘甲又蓝色(MB ) 和 DNA，在 DNA 的 MB 的 photosensitization，和 photosensitization 和有约束力的模式的关联的绑定在 DNA 和 MB 的不同集中比率被学习。吸收系列显示静电的绑定是在低比率(2 ) 的主要模式，当时在高比率(> 2 ) intercalative 绑定被统治。为在 DNA 的 MB 的汗衫氧(1O2 ) 的 photosensitization 形成的动力学上的研究被使用解决时间的技术执行。没有汗衫氧一生和三位字节状态 MB 分子的明显的变化(MB3+*) 在低比率的一生，他们分别地是大约 4 s 和 1 s。然而，我们不能获得 1O2 一生和 MB3+* 由于 1O2 的大减少，磷光在高比率表明的一生。这些结果证明 photosensitization 和在 DNA 的 MB 的有约束力的模式拥有高关联。当 MB 由静电的相互作用与 DNA 绑时， MB 的 type-II photosensitization 在光力学的效果起一个主要作用， DNA 的损坏能可能被归功于到 1O2。在高比率，然而，在 MB 和 DNA 之间的有约束力的模式转到 intercalative 绑定，它极大地削弱 type-II photosensitization 进程。在 MB 和 DNA 之间的费用转移可能成为主要损坏机制。
基金Supported by the National Natural Science Foundation of China,No.11622542 and No.51677145
文摘BACKGROUND Hepatocellular carcinoma(HCC) is one of the most common malignant tumors worldwide, and novel methods for early/rapid diagnosis of HCC are needed.Terahertz(THz) spectroscopy is considered to have the potential to distinguish between normal liver tissue and HCC tissue; however, there are few reports on it.We conduct this observational study to explore the feasibility of THz imaging for the diagnosis of HCC.AIM To evaluate the feasibility of THz for discriminating between HCC and normal liver tissues using fresh tissue specimens obtained from HCC patients who had undergone surgery.METHODS Normal liver tissue and HCC tissue were cryosectioned into 50 μm-thick slicesand placed on cover glass. Two adjacent tissue sections were separated subjected to histopathological examination by hematoxylin and eosin staining or THz transmission examination, and THz images were compared with pathologically mapped images. We determined the typical tumor and normal liver tissue regions by pathological examination; the corresponding areas of adjacent sections were examined by THz transmission.RESULTS The transmission rate of HCC tissue was 0.15-0.25, and the transmission rate of typical HCC tissue was about 0.2. THz transmittance in normal liver tissue is slightly higher than 0.4, but there were many influencing factors, including the degree of liver cirrhosis, fat components, ice crystals in frozen sections, and apoptosis.CONCLUSION In conclusion, this study shows that THz imaging can detect HCC tissue. Further research will yield more detailed data of the THz transmission rates of HCC tissue with different degrees of differentiation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50872089,61077039 and 61377060the Research Grants Council of the Hong Kong Special Administrative Region of China under Grant No 11211014+1 种基金the Key Program for Research on Fundamental to Application and Leading Technology of Tianjin Science and Technology Commission of China under Grant No 11JCZDJC15500the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20100032110052
文摘Transmission spectra of triangular lattice photonic crystals milled in the top surface of an annealed protonexchange waveguide are numerically simulated.The effects of the finite depth,conical shape,trapezoidal shape and hybrid shape of holes are theoretically analyzed.Due to the difficulty of milling high aspect-ratio cylindrical holes in lithium niobate(LiNbO_3),a compromised solution is proposed to improve the overlap between shallow holes and the waveguide mode,and useful transmission spectra with strong contrast and sharp band edges are achieved.
基金Supported by the Research Fund for the Doctoral Program of Higher Education under Grant No 20070420118, the Tianjin Municipal Primary Application and Frontier Technology Research Plan under Grant No 07JCYBJC06200, the National Basic Research Program of China under Grant No 2007CB310403, and the National Natural Science Foundation of China under Grant No 60801017.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61701434,61735010,and 61675147)the Open Fund of the Key Laboratory of Optoelectronic Information Technology,Ministry of Education(Tianjin University),China+5 种基金the Key Laboratory of Optoelectronic Information Functional Materials and Micro-Nano devices in Zaozhuang,Chinathe China Postdoctoral Science Foundation(Grant No.2015M571263)the Natural Science Foundation of Shandong Province,China(Grant Nos.ZR2017MF005 and ZR2018LF001)Project of Shandong Province Higher Education Science and Technology Program,China(Grant No.J17KA087)the Program of Independent and Achievement Transformation Plan for Zaozhuang,China(Grant Nos.2016GH19 and2016GH31)aozhuang Engineering Research Center of Terahertz,China
文摘The dynamic tunability of a terahertz(THz) passband filter was realized by changing the Fermi energy(E_F) of graphene based on the sandwiched structure of metal-graphene-metal metamaterials(MGMs). By using plane wave simulation, we demonstrated that the central frequency( f_0) of the proposed filter can shift from 5.04 THz to 5.71 THz; this shift is accompanied by a 3 dB bandwidth(? f) decrease from 1.82 THz to 0.01 THz as the EFincreases from 0 to 0.75 eV.Additionally, in order to select a suitable control equation for the proposed filter, the curves of ? f and f_0 under different graphene EFwere fitted using five different mathematical models. The fitting results demonstrate that the Dose Resp model offers accurate predictions of the change in the 3 dB bandwidth, and the Quartic model can successfully describe the variation in the center frequency of the proposed filter. Moreover, the electric field and current density analyses show that the dynamic tuning property of the proposed filter is mainly caused by the competition of two coupling effects at different graphene EF, i.e., graphene-polyimide coupling and graphene-metal coupling. This study shows that the proposed structures are promising for realizing dynamically tunable filters in innovative THz communication systems.
基金Project supported by the National Natural Science Foundation of China(Grant No.62075159)the National Key Research and Development Program of China(Grant No.2017YFF0104603)+1 种基金the 111 Project of China(Grant No.B17031)the Major Scientific and Technological Innovation Projects of Key Research and Development Plans in Shandong Province,CHina(Grant No.2019JZZY020206)。
文摘Based on the index-induced mode coupling between the higher-order mode in core and the fundamental mode in cladding tubes,the single-mode operation can be realized in any antiresonant fibers(ARFs)when satisfying that the area ratio of cladding tube and core is about 0.46:1,and this area ratio also should be modified according to the shape and the number of cladding tubes.In the ARF with nodal core boundary,the mode in core also can couple with the mode in the wall of core boundary,which can further enhance the suppression of high-order mode.Accordingly,an ARF with conjoint semi-elliptical cladding tubes realizes a loss of higher-order mode larger than 30 dB/m;simultaneously,a loss of fundamental mode loss less than 0.4 dB/m.
基金Project supported by the National Basic Research Program of China(Grant Nos.2015CB755403 and 2014CB339802)the National Key Research and Development Program of China(Grant No.2016YFC0101001)+3 种基金the National Natural Science Foundation of China(Grant Nos.61775160,61771332,and 61471257)China Postdoctoral Science Foundation(Grant No.2016M602954)Postdoctoral Science Foundation of Chongqing,China(Grant No.Xm2016021)the Joint Incubation Project of Southwest Hospital,China(Grant Nos.SWH2016LHJC04 and SWH2016LHJC01)
文摘A compact terahertz(THz) imaging system based on complementary compressive sensing has been proposed using two single-pixel detectors. By using a mechanical spatial light modulator, sampling in the transmission and reflection orientations was achieved simultaneously, which allows imaging with negative mask values. The improvement of THz image quality and anti-noise performance has been verified experimentally compared with the traditional reconstructed image, and is in good agreement with the numerical simulation. The demonstrated imaging system, with the advantages of high imaging quality and strong anti-noise property, opens up possibilities for new applications in the THz region.
基金This work was supported by the National Natural Science Foundation of China(Nos.61975146 and 62075159)Major Scientific and Technological Innovation Projects of Key R&D Plans in Shandong Province(No.2019JZZY020206)+1 种基金National Key R&D Program of China(No.2017YFF0104603)Foundation for Distinguished Young Scholars of China Academy of Space Technology(2021).
文摘A multi-lens retroreflector with field curvature compensation was designed and used in an alignment-free distributed-cavity laser with a long working distance for resonant beam charging applications.The multi-lens design,which makes use of off-the-shelf components,also allows a large field of view[FoV]without requirement of large element aperture.By implementing this design,an end-pumped 1063 nm Nd:GdVO4 laser could deliver over 5 W continuous-wave output power over a large range of working distances(1-5 m)and with ±30°receiver FoV under an incident diode pump power of 16.6 W.The output power fluctuation was less than 10%when moving and tilting the receiver over such a large range,without requiring any realignment of the cavity.
