排序方式: 共有77条查询结果,搜索用时 0 毫秒
71.
72.
TM-like and TE-like Modes Coupling in a Two-Dimensional Photonic Crystal Slab Composed of Truncated Cone Silicon Rods 下载免费PDF全文
We numerically investigate the coupling of TE-like modes and TM-like modes in a two-dimensional (2D) photonic crystal (PC) slab composed of truncated cone silicon rods. In such structures, the classification of TE-like modes and TM-like modes is generally impossible and the coupling occurs due to vertical structural asymmetries. The frequency and wavevector dependences of the mode coupling are discussed by investigating the photonic band structures, and the coupling efficiency is studied by examining the transmittance. The results show that the efficiency of mode conversion is strengthened by the vertical asymmetry and weakened by the clear sinall gap. These structures could be used as polarization conversion devices in integrated optics. 相似文献
73.
Optical properties of the two-port resonant tunneling filters in two-dimensional photonic crystal slabs 下载免费PDF全文
We have designed and fabricated two types of two-port resonant tunneling filters with a triangular air-hole lattice in two-dimensional photonic crystal slabs.In order to improve the filtering efficiency,a feedback method is introduced by closing the waveguide.It is found that the relative position between the closed waveguide boundary and the resonator has an important impact on the dropping efficiency.Based on our analyses,two different types of filters are designed.The transmission spectra and scattering-light far-field patterns are measured,which agree well with theoretical prediction.In addition,the resonant filters are highly sensitive to the size of the resonant cavities,which are useful for practical applications. 相似文献
74.
Various Mie scattering systems, each having a transparent matrix, are studied in the mid-infrared region. Our three theoretical scattering systems correspond to a lossless scatterer, an anomalous dispersive dielectric scatterer and a metal scatterer, each in a non-air usual matrix. The refractive-index effects of the matrix on scattering and extinction efficiencies in the mid-infrared region are found to be quite different in different cases. Although the non-air usual matrix reduces scattering and extinction efficiencies in the first kind of system, it may or may not help scatter and extinguish the mid-infrared radiation in the second, and it has little effect on them in the third. 相似文献
75.
We propose a ring photonic crystal working in the near infrared region, where the air holes in the background material GaAs are arranged to form a series of rings. We find that the band gaps do not depend on the incident direction, and only a small number of rows are needed to create a frequency gap in the transmission spectrum. The transmission spectra of both P and S polarizations show that there is a complete bandgap in the hexagonal ring photonic crystals and the ratio of gap width to mid-gap frequency is as high as 11%. 相似文献
76.
Trapping force of an optical tweezers system with an oil immersion objective is calculated with a ray-optics model. Results indicate that the trapping force will be decreased as a result of the introduction of spherical aberration, which is caused by the refractive mismatch between objective oil and water, when the sample manipulated is suspended in a water solution. The effect of spherical aberration will be serious when the detection depth of the optical tweezers is enhanced. 相似文献
77.
The extraordinary light transmission through a 200-nm thick gold
film when passing through different subwavelength hole arrays is
observed experimentally. The sample is fabricated by electron beam
lithography and reactive ion etching system. A comparison between
light transmissions shows that the hole shape changing from
rectangular to diamond strongly affects the transmission intensity
although both structures possess the same lattice constant of
600,nm. Moreover, the position of the transmission maximum
undergoes a spectral red-shift of about 63,nm. Numerical
simulations by using a transfer matrix method reproduce the observed
transmission spectrum quite well. 相似文献