Rigorous Coupled-Wave Approach (RCWA) has been used successfully and accurately to study simple grating structures, such as one-layer gratings, one-whole gratings. In this paper, RCWA is expanded to solve Sandwich gra...Rigorous Coupled-Wave Approach (RCWA) has been used successfully and accurately to study simple grating structures, such as one-layer gratings, one-whole gratings. In this paper, RCWA is expanded to solve Sandwich gratings (SG), which is composed of two identical planar dielectric gratings adjoined by thin metallic or dielectric film. The electromagnetic analytic expressions for each layer of SG structure are given and rigorous coupled-wave equations are deduced. The numerical investigations for the diffraction spectra of SG by our theoretical and computer programs are in good agreement with the results of classical RCWA in the condition when a Sandwish grating is simplified to a classical one-layer grating. The calculations by our programs of another condition when a Sandwish grating is degenerated to a classical single planar structure also conform to the results of classical electromagnetic theory. The research results above indicate that the extended theoretical formula has backwards compatibility and is self-consistent with the classical theory.展开更多
In this paper, a new type of resonant Brewster filters （RBF） with surface relief structure for the multiple channels is first presented by using the rigorous coupled-wave analysis and the S-matrix method. By tuning ...In this paper, a new type of resonant Brewster filters （RBF） with surface relief structure for the multiple channels is first presented by using the rigorous coupled-wave analysis and the S-matrix method. By tuning the depth of homogeneous layer which is under the surface relief structure, the multiple channels phenomenon is obtained. Long range, extremely low sidebands and multiple channels are found when the RBF with surface relief structure is illuminated with Transverse Magnetic incident polarization light near the Brewster angle calculated with the effective media theory of sub wavelength grating. Moreover, the wavelengths of RBF with surface relief structure can be easily shifted by changing the depth of homogeneous layer while its optical properties such as low sideband reflection and narrow band are not spoiled when the depth is changed. Furthermore, the variation of the grating thickness does not effectively change the resonant wavelength of RBF, but have a remarkable effect on its line width, which is very useful for designing such filters with different line widths at desired wavelength.展开更多
The excitation of a surface-plasmon-polariton(SPP) wave guided by a columnar thin film(CTF) deposited on a one-dimensional metallic surface-relief grating was investigated for sensing the refractive index of a fluid i...The excitation of a surface-plasmon-polariton(SPP) wave guided by a columnar thin film(CTF) deposited on a one-dimensional metallic surface-relief grating was investigated for sensing the refractive index of a fluid infiltrating that CTF. The Bruggemann homogenization formalism was used to determine the relative permittivity scalars of the CTF infiltrated by the fluid. The change in the refractive index of the fluid was sensed by determining the change in the incidence angle for which an SPP wave was excited on illumination by a p-polarized plane wave, when the plane of incidence was taken to coincide with the grating plane but not with the morphologically significant plane of the CTF. Multiple excitations of the same SPP wave were found to be possible, depending on the refractive index of the fluid, which can help increase the reliability of results by sensing the same fluid with more than one excitation of the SPP wave.展开更多
The micro/nano structures of the wing scales in Morpho butterfly are responsible for the structural coloration,with a major part ascribed to interference and diffraction of light.The optical properties of the butterfl...The micro/nano structures of the wing scales in Morpho butterfly are responsible for the structural coloration,with a major part ascribed to interference and diffraction of light.The optical properties of the butterfly wings were investigated by simulating a two-dimensional model using rigorous coupled-wave analysis technique.It is proved that they depend strongly on the structural parameters,incidence angle and refractive index.The peak value and the peak wavelength of the reflection efficiency increase as the vertical periodic thickness increases.The peak value decreases observably,while both of the bandwidth and the peak wavelength increase when the number of the vertical periods decreases.Increase of the horizontal periodic width causes a decrease of the peak value and an increase of the peak wavelength,although the variations are small.The peak value decreases distinctly and the peak wavelength increases as the ambient refractive index increases,which corresponds to the variation in ambient conditions.The research reveals the mechanisms of the brilliant structural color in Morpho butterfly,and is of great significance to the design,manufacture and applications of the bionic micro/nano structures for gas detection.展开更多
文摘Rigorous Coupled-Wave Approach (RCWA) has been used successfully and accurately to study simple grating structures, such as one-layer gratings, one-whole gratings. In this paper, RCWA is expanded to solve Sandwich gratings (SG), which is composed of two identical planar dielectric gratings adjoined by thin metallic or dielectric film. The electromagnetic analytic expressions for each layer of SG structure are given and rigorous coupled-wave equations are deduced. The numerical investigations for the diffraction spectra of SG by our theoretical and computer programs are in good agreement with the results of classical RCWA in the condition when a Sandwish grating is simplified to a classical one-layer grating. The calculations by our programs of another condition when a Sandwish grating is degenerated to a classical single planar structure also conform to the results of classical electromagnetic theory. The research results above indicate that the extended theoretical formula has backwards compatibility and is self-consistent with the classical theory.
基金Project supported by the National Natural Science Foundation of China (Grant No 10704079)
文摘In this paper, a new type of resonant Brewster filters （RBF） with surface relief structure for the multiple channels is first presented by using the rigorous coupled-wave analysis and the S-matrix method. By tuning the depth of homogeneous layer which is under the surface relief structure, the multiple channels phenomenon is obtained. Long range, extremely low sidebands and multiple channels are found when the RBF with surface relief structure is illuminated with Transverse Magnetic incident polarization light near the Brewster angle calculated with the effective media theory of sub wavelength grating. Moreover, the wavelengths of RBF with surface relief structure can be easily shifted by changing the depth of homogeneous layer while its optical properties such as low sideband reflection and narrow band are not spoiled when the depth is changed. Furthermore, the variation of the grating thickness does not effectively change the resonant wavelength of RBF, but have a remarkable effect on its line width, which is very useful for designing such filters with different line widths at desired wavelength.
基金partial support from HEC,Pakistan,via grant 2016-5905the Charles Godfrey Binder Endowment at Penn State for ongoing support of his research activities。
文摘The excitation of a surface-plasmon-polariton(SPP) wave guided by a columnar thin film(CTF) deposited on a one-dimensional metallic surface-relief grating was investigated for sensing the refractive index of a fluid infiltrating that CTF. The Bruggemann homogenization formalism was used to determine the relative permittivity scalars of the CTF infiltrated by the fluid. The change in the refractive index of the fluid was sensed by determining the change in the incidence angle for which an SPP wave was excited on illumination by a p-polarized plane wave, when the plane of incidence was taken to coincide with the grating plane but not with the morphologically significant plane of the CTF. Multiple excitations of the same SPP wave were found to be possible, depending on the refractive index of the fluid, which can help increase the reliability of results by sensing the same fluid with more than one excitation of the SPP wave.
文摘The micro/nano structures of the wing scales in Morpho butterfly are responsible for the structural coloration,with a major part ascribed to interference and diffraction of light.The optical properties of the butterfly wings were investigated by simulating a two-dimensional model using rigorous coupled-wave analysis technique.It is proved that they depend strongly on the structural parameters,incidence angle and refractive index.The peak value and the peak wavelength of the reflection efficiency increase as the vertical periodic thickness increases.The peak value decreases observably,while both of the bandwidth and the peak wavelength increase when the number of the vertical periods decreases.Increase of the horizontal periodic width causes a decrease of the peak value and an increase of the peak wavelength,although the variations are small.The peak value decreases distinctly and the peak wavelength increases as the ambient refractive index increases,which corresponds to the variation in ambient conditions.The research reveals the mechanisms of the brilliant structural color in Morpho butterfly,and is of great significance to the design,manufacture and applications of the bionic micro/nano structures for gas detection.
