Mid-infrared transmittance of submicron silver slit arrays was numerically studied with the finite difference time domain method. The slit width varies from 50 nm to 300 nm and a square feature may attach at either or...Mid-infrared transmittance of submicron silver slit arrays was numerically studied with the finite difference time domain method. The slit width varies from 50 nm to 300 nm and a square feature may attach at either or both slit sides. Although the side length of features is one or two orders of magnitude shorter than the wavelength, the attached nanoscale features can modify the transmittance significantly. The transmittance was also further investigated in detail by looking into the electromagnetic fields and Poynting vectors of selected slit geometries. The investigation results show that such change can be attributed to the cavity resonance effect inside the slit arrays. The work is of great importance to the wavelength-selective devices design in optical devices and thermal application fields.展开更多
We investigate the relationship between the transmission and the layer distance of double-layer gold slit arrays by using the finite-difference time-domain method. The results show that the transmission properties can...We investigate the relationship between the transmission and the layer distance of double-layer gold slit arrays by using the finite-difference time-domain method. The results show that the transmission properties can be influenced strongly by layer distance. We attribute the two types of resonant modes to surface plasmon resonance and the localised waveguide resonance. We find that the localised waveguide transmission peak redshifts and becomes broader with increasing layer distance D. We also describe and explain the splitting, shift, and degeneration of the surface plasmon resonant transmission peak theoretically. In addition, to clarify the physical mechanism of the transmission behaviours, we analyse the distributions of electric field and total energy for the three transmission peaks with distance D = 45 nm for the double-layer system. Light transporting behaviours are mostly concentrated in the region of the slits as well as the interspaces of the two layers, and for different resonant wavelengths the electric field and energy distributions are different. It is expected that the results obtained here will be helpful for designing subwavelength metallic grating devices.展开更多
This paper has made a theoretical study of enhanced transmission through a gold grating with arrays of subwavelength slits filled with nonlinear Kerr medium. The results of the research are based on rigorous finite-di...This paper has made a theoretical study of enhanced transmission through a gold grating with arrays of subwavelength slits filled with nonlinear Kerr medium. The results of the research are based on rigorous finite-difference time domain calculations. The resonance transmission peaks in the investigated wavelength range are produced as a result of the surface plasmon resonance collaborated with the localized waveguide resonance. The paper also gives a detailed analysis of the influence exerted by various factors: thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays and the incident intensity to the transmission. It is found that the small changes of parameters such as medium thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays as well as the incident intensity can bring great changes of lateral shift and magnitude variation of the transmission resonance peaks. The report proposes that these phenomena can be applied to designing precise optical switches.展开更多
基金Project(N110402015) supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2012M510075) supported by China Postdoctoral Science Foundation
文摘Mid-infrared transmittance of submicron silver slit arrays was numerically studied with the finite difference time domain method. The slit width varies from 50 nm to 300 nm and a square feature may attach at either or both slit sides. Although the side length of features is one or two orders of magnitude shorter than the wavelength, the attached nanoscale features can modify the transmittance significantly. The transmittance was also further investigated in detail by looking into the electromagnetic fields and Poynting vectors of selected slit geometries. The investigation results show that such change can be attributed to the cavity resonance effect inside the slit arrays. The work is of great importance to the wavelength-selective devices design in optical devices and thermal application fields.
基金supported by the National Natural Science Foundation of China (Grant No. 60708014)the Science Foundation for Postdoctorate of China (Grant No. 2004035083)+2 种基金the Natural Science Foundation of Hunan Province of China (Grant No. 06JJ2034)the Excellent Doctorate Dissertation Foundation of Central South University of China (Grant No. 2008yb039)the Hunan Provincial Innovation Foundation for Postgraduate (Grant No. CX2009B029)
文摘We investigate the relationship between the transmission and the layer distance of double-layer gold slit arrays by using the finite-difference time-domain method. The results show that the transmission properties can be influenced strongly by layer distance. We attribute the two types of resonant modes to surface plasmon resonance and the localised waveguide resonance. We find that the localised waveguide transmission peak redshifts and becomes broader with increasing layer distance D. We also describe and explain the splitting, shift, and degeneration of the surface plasmon resonant transmission peak theoretically. In addition, to clarify the physical mechanism of the transmission behaviours, we analyse the distributions of electric field and total energy for the three transmission peaks with distance D = 45 nm for the double-layer system. Light transporting behaviours are mostly concentrated in the region of the slits as well as the interspaces of the two layers, and for different resonant wavelengths the electric field and energy distributions are different. It is expected that the results obtained here will be helpful for designing subwavelength metallic grating devices.
基金supported by the National Natural Science Foundation of China (Grant No. 60708014)the Distinguished Youth Foundation of Hu-nan Province (Grant No. 03JJY1008)+2 种基金the Science Foundation for Post-doctorate of China (Grant No. 2004035083)the Natural Science Foundation of Hunan Province (Grant No. 06JJ2034)the Excellent Doctorate Dissertation Foundation of Central South University (Grant No. 2008yb039)
文摘This paper has made a theoretical study of enhanced transmission through a gold grating with arrays of subwavelength slits filled with nonlinear Kerr medium. The results of the research are based on rigorous finite-difference time domain calculations. The resonance transmission peaks in the investigated wavelength range are produced as a result of the surface plasmon resonance collaborated with the localized waveguide resonance. The paper also gives a detailed analysis of the influence exerted by various factors: thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays and the incident intensity to the transmission. It is found that the small changes of parameters such as medium thickness, third-order susceptibility and line refractive index of the nonlinear medium filled in the gold slits arrays as well as the incident intensity can bring great changes of lateral shift and magnitude variation of the transmission resonance peaks. The report proposes that these phenomena can be applied to designing precise optical switches.
