共查询到20条相似文献,搜索用时 0 毫秒
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The response of antenna-coupled thin-film Ni-NiO-Ni diodes to 633-nm helium-neon laser radiation is investigated. Although these detectors and their integrated dipole antennas are optimized for the detection of mid-infrared radiation, a polarization dependence of the measured response to visible radiation is observed. The strongest signals are measured for the polarization parallel to the dipole antenna axis, which demonstrates antenna operation of the device in the visible in addition to the expected thermal and photoelectric effects. The connection structure of the diode also resonates and contributes to the polarization-dependent signal. The receiving area of the dipole antenna is approximately 2mum (2) . 相似文献
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Enkrich C Wegener M Linden S Burger S Zschiedrich L Schmidt F Zhou JF Koschny T Soukoulis CM 《Physical review letters》2005,95(20):203901
Arrays of gold split rings with a 50-nm minimum feature size and with an LC resonance at 200 THz frequency (1.5 microm wavelength) are fabricated. For normal-incidence conditions, they exhibit a pronounced fundamental magnetic mode, arising from a coupling via the electric component of the incident light. For oblique incidence, a coupling via the magnetic component is demonstrated as well. Moreover, we identify a novel higher-order magnetic resonance at around 370 THz (800 nm wavelength) that evolves out of the Mie resonance for oblique incidence. Comparison with theory delivers good agreement and also shows that the structures allow for a negative magnetic permeability. 相似文献
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An analytic intensity expression of the reflected light from a liquid surface with acoustic wave at a few tens Hertz was derived. The expression displays a distinct modulated oscillation. Meanwhile high visibility and modulated interference fringes were obtained experimentally. Line scans across the reflection patterns indicate that the theory predication is well consistent with the experimental data. Moreover, a practical technique can be developed, based on this study, to determine the wavelength and amplitude of the SAW at these frequencies as well as the dynamic surface tension. 相似文献
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We theoretically investigate a thin single metal layer covered on sub-wavelength dielectric grating. Numerical simulations show that the structure has negative index in the normal direction at visible frequencies. Structural investigation demonstrates that the simultaneous negative permittivity and permeability at an overlapping frequency range are attributed to the metal cut-wire and “U”-shaped structure disassembled from the structure, respectively. Furthermore, parametric exploration for practical fabrication is presented. 相似文献
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基于树枝结构单元思想,提出了光频三维各向同性左手超材料球刺结构单元模型.采用金属的Drude原理,运用等效媒质理论,仿真研究了结构的电磁响应特性.在晶格间距与工作波长的比值满足等效媒质理论要求的前提下,通过调节结构单元的几何参数,发现它能在光波段出现介电常数和磁导率同时为负值的区域,实现折射率小于零的左手超材料响应特性.该模型结构简单,具有各向同性特点.研究结果为采用"由下向上"方法制备光波段的三维左手超材料指出了新的途径.
关键词:
球刺模型
光波段
三维
各向同性 相似文献
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We show analytically and numerically that diamagnetic response (effective magnetic permeability mue<1) at infrared and visible frequencies can be achieved in photonic crystals composed of metallic nanowires or nanospheres when the wavelength is much larger than the lattice constant a (lambda approximately 2000a). When lambda approximately100a, the metallic photonic crystals will exhibit strong diamagnetic response (mue<0.8), leading to many interesting phenomena such as the unusual Brewster angle for s waves and incident-angle-and-polarization-independent reflection and transmission. 相似文献
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X.M. Li Y.C. Chang J.F. Song Y.S. Zhao G.T. Du J. A. Lott R. P. H. Chang 《Optical and Quantum Electronics》1999,31(4):303-306
Visible VCSEL laser operated at room temperature continuous wave has been achieved by H+ implants using tungsten wires as an implantation mask. The laser wavelength is 650 nm, and the maximum output without heat-sink exceeds 85 W at CW operation. We also calculated the thermal resistance of the device. 相似文献
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Jiu-sheng Li 《Optik》2014
We demonstrate, for the first time, a tunable dual-wavelength terahertz wave power splitter based on the multimode interference effect and self-imaging principle in 1 × 2 × 2 photonic crystal waveguides. Both plane wave expansion method and finite-difference time-domain method are used to calculate and analyze the characteristics of the proposed device. The simulation results demonstrate that the power splitter not only split the input power into output1 and output2 branches with equal power at frequency of 1.09 THz, but also split the power into output3 and output4 branches symmetrically at frequency of 1.20 THz. Furthermore, for the frequency of 1.09 THz, the input terahertz wave power can be split into output1 and output2 branches with an arbitrary ratio by tuning the refractive index of the tuning rods. 相似文献
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G. E. Stratakos N. V. Vlassopoulos N. K. Uzunoglu C. N. Capsalis 《International Journal of Infrared and Millimeter Waves》1995,16(8):1367-1392
Millimeter wave frequencies are proposed as carriers of microcell future mobile systems. High frequencies in the region of 60–62 Ghz are suggested. A serious difficulty in this context is the lack of sufficient gain in active devices. Both on receiver and transmitter units this difficulty is faced. Mixing, amplification, carrier recovery and modulation / demodulation subsytems are required to be operational at these higher frequencies. Presently the MMIC 's show also limited performance. In this report an alternative approach active processing technique is examined based on an injection locking in Gunn oscillator. A non-linear analysis is applied to determine the fundamental properties of injection locking in Gunn oscillator performance under the influence of an external signal. Details of waveguide action is taken into account by solving the corresponding boundary condition problem. Finally experimental results are presented for a 30GHz oscillator. 相似文献
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We study theoretically wideband modulation instability at combination frequencies in media having cubic nonlinearity of self-focusing
type along with the higher-order defocusing nonlinearity. It is assumed that in a medium with a purely cubic nonlinearity,
the medium dispersion does not permit modulation instability. In this case, a collapse of the wave field exists if the beam
power is higher than the critical power of self-focusing. The higher-order nonlinearity limits the field at the nonlinear
focus, and the instability at combination frequencies becomes possible. It turns out that the field at the nonlinear focus
increases with increasing excess of the beam power over the critical power of self-focusing. The obtained values of the nonlinear
dielectric permittivity are used for determination of the growth rates of instability at combination frequencies. These growth
rates ensure an increase in the combination fields from noise levels up to values comparable with the field of the high-power
beam. Such an increase takes place if the beam power is severalfold higher than the critical one. The developed theory can
be used for explanation of spectrum superbroadening during self-focusing of sufficiently short laser pulses and high-harmonic
generation.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 6, pp. 522–532, June 2007. 相似文献
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In this paper, we design a THz wave polarizer based on a periodic symmetrical thin film structure, which operates over a broadband THz frequency region (1.0–2.0 THz) and over an effective wide range of incident THz wave (72–84°). The spectral performance of this structure is characterized by transfer matrix method calculations. Results of simulations show that the polarizer is highly transmittance for TE polarized THz wave as well as highly reflecting for TM polarized THz wave. 相似文献
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Finite size corrections of Bhalla and Rose are examined in the midway to the point-nucleus limit. A possible reason of poor convergence of their positron wave functions is suggested. 相似文献
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We report the propagation of surface polaritons over macroscopic distances along copper-air interfaces at 10.6 μm wavelength using a prism coupling technique for generating and detecting the surface modes. The measured propagation length (~ 1.6cm) is in agreement with theoretical estimates based on available optical data. The surface polaritons are easily observed visually using Radelin thermographic phosphor paper. 相似文献
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Zhihui Wang 《Optik》2014
In this paper, a theoretical study of the influence of surface roughness on conductor is proposed at terahertz frequencies. By using the analytic small perturbation method, the effects of a random rough surface on the absorption by a metallic surface at terahertz frequencies are analyzed. And the effect of rough surface on reflectivity and power spectral density are also demonstrated. The numerical results are very useful for the development of terahertz devices and terahertz material. 相似文献
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Hao Chi Zhang Shuo Liu Xiaopeng Shen Lin Hui Chen Lianming Li Tie Jun Cui 《Laser \u0026amp; Photonics Reviews》2015,9(1):83-90
Efficient amplification of spoof surface plasmon polaritons (SPPs) is proposed at microwave frequencies by using a subwavelength‐scale amplifier. For this purpose, a special plasmonic waveguide composed of two ultrathin corrugated metallic strips on top and bottom surfaces of a dielectric substrate with mirror symmetry is presented, which is easy to integrate with the amplifier. It is shown that spoof SPPs are able to propagate on the plasmonic waveguide in broadband with low loss and strong subwavelength effect. By loading a low‐noise amplifier chip produced by the semiconductor technology, the first experiment is demonstrated to amplify spoof SPPs at microwave frequencies (from 6 to 20GHz) with high gain (around 20dB), which can be directly used as a SPP amplifier device. The features of strong field confinement, high efficiency, broadband operation, and significant amplification of the spoof SPPs may advance a big step towards other active SPP components and integrated circuits.