共查询到20条相似文献,搜索用时 31 毫秒
1.
We show that the polarization of linearly polarized light can be rotated an arbitrary angle by double-layer metal hole array structures in a subwavelength regime. The transmitted light with the rotated polarization, however, remains of nearly the same strength as the incident field at particular frequencies. The mechanism can be attributed to the subwavelength feature of the rectangular holes, and the tangential guiding modes between layers modulated by the orientation of the holes. The structures have potential applications as polarization rotators in a broad frequency range covering from terahertz (THz) to infrared frequencies. 相似文献
2.
The waveguide propagation properties of terahertz wave through subwavelength semiconductor trench have been simulationally investigated. The effects of gap width, temperature, doping concentration and dielectric filling materials on waveguide property have been given and discussed. The results show that as temperature and doping concentration increases, the skin depth and the propagation constant decreases. In addition, the effective index increases and the propagation length decreases as the dielectric constant of filling materials increases. 相似文献
3.
I. Glesk P. J. Bock P. Cheben J. H. Schmid J. Lapointe S. Janz 《Optical and Quantum Electronics》2012,44(12-13):613-621
We investigate the picosecond switching capabilities of a planar waveguide interferometric photonic device when used for all-optical wavelength conversion of one picosecond pulses. Our device comprises a subwavelength grating waveguide arm and a photonic wire waveguide arm in a Mach–Zehnder configuration, fabricated on the silicon-on-insulator material platform. No detrimental effects of pulse broadening for transient pulses were observed. 相似文献
4.
We study the influence of dielectric function of metals on the transmission properties of terahertz pulses through periodically patterned subwavelength holes. Because of a drastic increase in the value of dielectric constants, most metals become highly conductive at terahertz frequencies. Extraordinary terahertz transmission is observed in subwavelength hole arrays made from both good and poor electrical conductors. The measured transmittance of terahertz pulses is found to be enhanced with increasing ratio of the real to the imaginary dielectric constant of the constituent metals, for which the dielectric function follows the Drude model. 相似文献
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The extraordinary transmission spectrum of a copper film pierced by a periodic array of subwavelength rectangular holes is measured by the terahertz time-domain spectroscopy. The transmission coefficient is strongly dependent on the angle between the polarization of terahertz electric field and the latitudinal direction of the periodic apertures. When the angle increases from 0o to 90o, a peak becomes stronger and another peak reduces. The transmission is proposed to be the contributions of localized surface plasmons inside the apertures. The finite-difference-time-domain (FDTD) simulation results are in good agreement with experimental observations. 相似文献
7.
Hamid Reza Zangeneh Marzieh Asadnia Fard Jahromi 《Applied physics. B, Lasers and optics》2014,117(2):605-609
We present a suspended waveguide consists of a double hybrid plasmonic waveguide for the purpose of enhancing the conversion efficiency of terahertz (THz) wave generation using difference frequency generation process. We show that in the THz generation process, metal-air-metal waveguide facilitates the phase matching and reduces the propagation loss. Our numerical calculation shows that the conversion efficiency in these waveguide structures can be more than one order of magnitude larger than what has been achieved using regular metal-dielectric-metal waveguides. 相似文献
8.
We describe an experimental and theoretical characterization of rectangular resonant cavities integrated into parallel-plate waveguides, using terahertz pulses. When the waveguide is excited with the lowest-order transverse-electric mode, these cavities exhibit resonances with narrow linewidths. Broadband transmission spectra are compared with the results of mode-matching calculations, for various cavity dimensions. 相似文献
9.
利用三维电磁场时域有限差分法,对0.3~0.4 THz高功率太赫兹脉冲作用下置于矩形波导内部宽边中心的n型硅块响应规律进行了研究。通过对置入硅块前后矩形波导内电磁场分布、电压驻波比及硅块内平均电场的模拟分析,得出硅块几何尺寸和电阻率对上述物理量的响应规律,硅块长、宽、高和电阻率均会对波导内电压驻波系数产生影响,其中以高度影响最为明显;硅块内平均电场在低频段和高频段单调性不一致。最后,在优化硅块长、宽、高及电阻率的基础上,给出了一种可用于该频段高功率太赫兹脉冲直接测量的电阻探测器芯片设计方案,其相对灵敏度约为0.509 kW-1,幅度波动不超过14%,电压驻波比不大于1.34。 相似文献
10.
V. A. Kukushkin 《Technical Physics》2008,53(10):1327-1331
Generation of terahertz pulses via mixing the Fourier harmonics of strongly focused near-IR pumping laser pulses in a plasmon
waveguide filled with a nonlinear medium is considered. At a certain choice of its parameters, this waveguide provides efficient
transverse confinement of the terahertz mode and a low dispersion of its refractive index. As a result, the system becomes
capable of generating short fairly intense terahertz pulses. Such an approach significantly (by a factor of 50) decreases
the pump power compared with that in the conventional (waveguide-free) schemes, which generate terahertz pulses from single
pumping pulses (optical rectification), and still yields the same intensity of the output terahertz pulse and conversion efficiency.
For the Ag-GaP-Ag structure taken as an example, optimal parameters of the plasmon waveguide and pumping pulse are found and
characteristics of the output terahertz pulse are calculated. 相似文献
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Numerical simulations were used to design a variety of high-Q resonant cavities for integration into a terahertz 2D photonic crystal waveguide. After fabrication, the transmission characteristics of each integrated cavity were explored. These photonic waveguide-coupled cavities demonstrate resonances with linewidths approaching 10 GHz. The results compare favorably to previous observations of rectangular waveguide cavities. Good agreement between the experimental results and the numerical simulations was obtained. 相似文献
13.
Experimental studies of extraordinary light transmission through periodic arrays of subwavelength square and rectangular holes in metal films
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We fabricate a series of periodic arrays of subwavelength
square and rectangular air holes on gold films, and measure the
transmission spectra of these metallic nanostructures. By changing
some geometrical and physical parameters, such as array period, air
hole size and shape, and the incident light polarization, we verify
that both global surface plasmon resonance and localized waveguide
mode resonance are influential on enhancing the transmission of
light through nanostructured metal films. These two resonances
induce different behaviours of transmission peak shift. The
transmission through the rectangular air-hole structures exhibits an
obvious polarization effect dependent on the morphology. Numerical
simulations are also made by a plane-wave transfer-matrix method and
in good consistency with the experimental results. 相似文献
14.
Velasco AV Calvo ML Cheben P Ortega-Moñux A Schmid JH Ramos CA Fernandez IM Lapointe J Vachon M Janz S Xu DX 《Optics letters》2012,37(3):365-367
The design and fabrication of an ultracompact silicon-on-insulator polarization converter is reported. The polarization conversion with an extinction ratio of 16 dB is achieved for a conversion length of only 10 μm. Polarization rotation is achieved by inducing a vertical asymmetry by forming in the waveguide core two subwavelength trenches of different depths. By taking advantage of the calibrated reactive ion etch lag, the two depths are implemented using a single mask and etching process. The measured converter loss is -0.7 dB and the 3 dB bandwidth is 26 nm. 相似文献
15.
One-way-propagating broadly tunable terahertz plasmonic waveguide at a subwavelength scale is proposed based on a metal-dielectric-semiconductor structure. Unlike other one-way plasmonic devices that are based on interference effects of surface plasmons, the proposed one-way device is based on nonreciprocal surface magneto plasmons under an external magnetic field. Theoretical and simulation results demonstrate that the one-way-propagating frequency band can be broadly tuned by the external magnetic fields. The proposed concept can be used to realize various high performance tunable plasmonic devices such as isolators, switches and splitters for ultracompact integrated plasmonic circuits. 相似文献
16.
We report a novel geometry that allows for the phase-matched generation of broadband terahertz radiation in a polymer-based parallel-plate metal waveguide by means of optical rectification. Both the optical pump beam and the generated terahertz radiation propagate in the fundamental mode of the waveguide. This allows for noncritical phase matching over a broad range of terahertz frequencies. We demonstrate guided-wave interaction lengths of up to 3 mm. 相似文献
17.
报道了利用脉宽可调的光子晶体光纤飞秒激光放大器抽运矩形波导结构的GaP晶体太赫兹(THz) 发射器产生频率可调谐的超快THz脉冲.非线性晶体中光整流过程产生的THz辐射频率随抽运光脉冲宽度而 变化. GaP波导THz发射器可通过波导的几何尺寸来控制色散,以达到增加有效作用长度和提高输出功率的目的. 不同横截面尺寸的波导型发射器的THz辐射峰值频率随相位匹配条件的改变而改变,加以脉宽调节技术, 可以在大频谱范围获得频谱精细可调的THz脉冲.实验中在1 mm×0.7 mm的波导型THz发射器中获得了 频率可调谐的THz脉冲.提出实现THz辐射频率大范围调谐的GaP波导型阵列发射器的实施方案. 相似文献
18.
Chernomyrdin N. V. Kucheryavenko A. S. Rimskaya E. N. Dolganova I. N. Zhelnov V. A. Karalkin P. A. Gryadunova A. A. Reshetov I. V. Lavrukhin D. V. Ponomarev D. S. Karasik V. E. Zaytsev K. I. 《Optics and Spectroscopy》2019,126(5):560-567
Optics and Spectroscopy - We propose a new method of terahertz microscopy for imaging of biological tissues with a subwavelength spatial resolution. It makes it possible to surmount the Abbe... 相似文献
19.
Optical transmission properties of subwavelength planar fractals in terahertz (THz) frequency regime are studied by means of time-domain spectroscopy. The transmission spectra with multiple pass bands and stop bands are observed. The tunable photonic band gaps are realized by changing the angle between the principle axis of planar fractal and the polarization of THz wave. The possible application of the subwavelength optical component is discussed. We attribute the detected transmittance from subwavelength fractals to localized resonances. 相似文献
20.
We report on the time-domain differentiation of light waves by metallic transmission gratings. Time-resolved terahertz experiments show that the first time derivative of an arbitrary waveform can be achieved by use of gratings of subwavelength period. The results are in accord with classical diffraction theory and may permit novel applications for tailoring few-cycle light pulses and ultrahigh-frequency optoelectronics. 相似文献