共查询到20条相似文献,搜索用时 15 毫秒
1.
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. 相似文献
2.
Bandpass filters based on guided-mode resonance effects in waveguide-grating structures are obtained by use of a genetic algorithm search-and-optimization routine. Calculated examples show that narrow linewidths, high peaks, and low sideband transmittances can be achieved in thin-film diffractive devices with few layers. A filter with a linewidth of 0.2 nm at a central wavelength of 0.55 microm is demonstrated in a two-layer-two-grating structure. At 10.6-microm wavelength, a filter consisting of a single binary grating is obtained that has a linewidth of 12.7 nm and extended, low sideband transmittance. A three-layer device with a surface relief Si grating and two underlying homogeneous layers of SiO(2) and Si yields a high-efficiency filter centered at 1.55 microm with a linewidth of 0.1 nm. 相似文献
3.
Amplitude filters with non-linear adaptive performance in the Fourier plane of a mirror optical system are considered. Panchromatic silver bromide layers with a printout effect are employed. The processing of binary and grey-scale images with the aid of a passively adaptive mirror filtering block is investigated. 相似文献
4.
Bandpass filters are reported based on double-stacked metamaterial layers separated by an air gap for operation at terahertz frequencies. Several stacking configurations were investigated designed for a ~0.5 THz center frequency. The filters exhibited improved spectral transmission properties when compared with conventional ones based on single metamaterial layers. 3 dB bandwidth of ~78 GHz and sidelobe suppression ratio >16 dB were determined when symmetric or asymmetric double layers were stacked. We demonstrate that superior frequency selectivity can be achieved when metamaterial layers with different unit cells are used. Good agreement was found between measured and simulated transmission response. 相似文献
5.
Guided-mode resonant Brewster filter consisting of two homogenous layers and a single grating with an equal refractive index 下载免费PDF全文
In this paper,a new type of resonant Brewster filter(RBF) consisting of two homogenous layers and a single grating with an equal refractive index is presented.The properties are studied by using the plane waveguide method(PWM) and rigorous coupled-wave analysis(RCWA).It is found that the variation of the grating thickness does not effectively change the position of the resonant wavelength,however it has a remarkable effect on the line width,and the resonant peak can be adjusted back to its original position by slightly tuning the grating period.Moreover,by simultaneously tuning the thicknesses of the homogeneous layers above and beneath the grating structure,multiple channels can also be obtained when the RBF is illuminated at the Brewster angle calculated with the effective medium theory(EMT) of subwavelength grating.The adjacent optical thickness for acquiring the multiple channels is about three-quarters of the resonant wavelength.Furthermore,it is demonstrated that the line width at the operating resonant wavelength can be appreciably narrowed by tuning the thickness of the homogenous layer to its corresponding thickness without fine tuning the grating period or the thickness.Therefore,it is very useful for designing filters with different line widths at the desired wavelength.In addition,it is shown from our calculations that the symmetrical line feather can be obtained if the total optical thickness for the homogeneous layer meets the special condition. 相似文献
6.
Guided-mode resonant Brewster filter consisting of two homogenous layers and a single grating with an equal refractive index 下载免费PDF全文
In this paper, a new type of resonant Brewster filter (RBF) consisting of two homogenous layers and a single grating with an equal refractive index is presented. The properties are studied by using the plane waveguide method (PWM) and rigorous coupled-wave analysis (RCWA). It is found that the variation of the grating thickness does not effectively change the position of the resonant wavelength, however it has a remarkable effect on the line width, and the resonant peak can be adjusted back to its original position by slightly tuning the grating period. Moreover, by simultaneously tuning the thicknesses of the homogeneous layers above and beneath the grating structure, multiple channels can also be obtained when the RBF is illuminated at the Brewster angle calculated with the effective medium theory (EMT) of subwavelength grating. The adjacent optical thickness for acquiring the multiple channels is about three-quarters of the resonant wavelength. Furthermore, it is demonstrated that the line width at the operating resonant wavelength can be appreciably narrowed by tuning the thickness of the homogenous layer to its corresponding thickness without fine tuning the grating period or the thickness. Therefore, it is very useful for designing filters with different line widths at the desired wavelength. In addition, it is shown from our calculations that the symmetrical line feather can be obtained if the total optical thickness for the homogeneous layer meets the special condition. 相似文献
7.
A surface plasmon resonance(SPR) sensor with a high-order absentee layer on the top of metallic film is proposed.The performance of the SPR sensor with NaCl, MgO, TiO_2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit(FOM) depends on the refractive index of absentee layer.By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO_2(or AlAs) absentee layer is 1.059%(or 2.587%) higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors. 相似文献
8.
Guided-mode resonance Brewster filter 总被引:1,自引:0,他引:1
A new type of optical filter is predicted theoretically and verified experimentally. The filter operates under guided-mode resonance conditions in a thin-film waveguide grating. A high-efficiency reflection filter response is produced at the Brewster angle at which TM reflection is classically prohibited. Low-reflectance sidebands are obtained that are adjacent to the resonance peak induced by the Brewster effect in the neighborhood of the resonance peak. A double-layer waveguide grating yields 94% experimental reflectance at the thin-film Brewster angle for a Gaussian laser beam with TM polarization at the 1064-nm wavelength. 相似文献
9.
《Solid State Communications》1986,58(12):833-838
Cyclotron Resonance measurements on accumulation-layer electrons at anodic oxide films on n-(Hg,Cd)Te are reported. Up to six subband cyclotron resonances are observed and discontinuities are seen in the subband effective masses, due to resonant polaron effects. The coupling is strongest for the higher subbands, where it is enhanced over that for the bulk, and occurs at the “HgTe-like” LO phonon frequency. The behaviour of the lowest (i=0,1) subbands is more complex, with the coupling being weaker and the dominant interaction seeming to occur at the TO frequency for low values of NS. 相似文献
10.
This paper is a first report on a theoretical and numerical study undertaken in order to understand the grating anomalies linked with an important absorption of energy. It is shown that metallic gratings can exhibit anomalies which consists of total absorption of a plane wave. 相似文献
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12.
We show that the energy of a plane wave incident on a layered structure can be totally absorbed if one of the layers has either dielectric or metallic losses. By interpreting this phenomenon in terms of a leaky-wave interaction, we explain similar total absorption effects that have been reported in the context of metallic gratings. 相似文献
13.
《Optik》2014,125(24):7247-7257
The effect of nanoscopically stratified anisotropic transmission layer between two isotropic dielectric medium on the characteristic Brewster angles is carried out. The analysis is based on the second-order approximate formulas for the quasi-Brewster, polarization (second Brewster), and principal (third Brewster) angles obtained in the framework of a long-wavelength approximation. The accuracy of these analytical expressions is estimated by using exact numerical methods for the solution of the anisotropic reflection problem. It is shown that the characteristics Brewster angles for real physical interfaces may differ considerably from the classical Brewster angle ϕB = arctg(nb/na), for certain material parameters even then, if the thickness of a transition layer is very significantly smaller than the wavelength of optical radiation. 相似文献
14.
An autocollimation system with an illuminated circular entrance aperture located in the front focal plane of a lens L is considered.
In the middle between S
0′ and L, a transparent plate a few millimeters thick is placed at an angle of i
0 = 45° to the axis of the system, and, near the rear focal plane of the lens L, a plane reflecting mirror is placed. The plate
divides the primary beam into parts during its propagation both forward and backward (after the reflection from the mirror).
This ensures the formation of derivative beams that propagate toward an ocular and that are overlapped in the region of spatially
separated images S
0, S
1, and S
2. The possibility of formation of a high-contrast system of first-order two-beam interference fringes in the region of S
2 is discussed. Conditions for achieving this result are also discussed. 相似文献
15.
从各向同性介质和各向异性单轴晶体界面间的菲涅耳公式出发,进一步研究了当自然光从各向同性介质射向各向异性且光轴任意取向的单轴晶体界面上时,其反射光成为垂直入射面的线偏振光时所对应的入射角,即布儒斯特角是否存在的问题,并对该问题进行了较全面的论述,计算了相应条件下的布儒斯特角和有关参量的数值,得到了正确的结论,同时也指出了某些文献在论述该问题时的不妥之处. 相似文献
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An internal Brewster guided-mode resonance (GMR) filter is designed. For this kind of GMR filter, the Brewster reflection occurs at the interface of grating/waveguide layers rather than at the interface of air/grating layers. At Brewster angle of 60~, the GMR filter owns almost 100% reflection at the resonance wavelength of 800 nm with the full-width at half-maximum (FWHM) of 0.2 nm. Its angle response changing with the fabrication deviation is also discussed. 相似文献
19.
By the use of a unitarity and reciprocity conserving theory for the scattering of p-polarized light from a one-dimensional random dielectric surface the we determine the shift in the Brewster angle toward smaller angles of incidence caused by the surface roughness, and the (non-zero) value of the reflectivity at its minimum. Both quantities may be useful in the characterization of the roughness of such surfaces. 相似文献
20.
We present an algorithm for the generalized search problem(searching6)marked items amongitems)based on a continuous Hamiltonian and exploiting resonance.This resonant algorithm has the same time complexity■as the Grover algorithm.A natural extension of the algorithm,incorporating auxiliary"mon√itor"qubits,can determine6)precisely,if it is unknown.The time complexity of our counting algorithm is■,similar to the best quantum approximate counting algorithm,or better,given appropriate physical resou... 相似文献