共查询到20条相似文献,搜索用时 531 毫秒
1.
High-damage-threshold static laser beam shaping using optically patterned liquid-crystal devices 总被引:1,自引:0,他引:1
Dorrer C Wei SK Leung P Vargas M Wegman K Boulé J Zhao Z Marshall KL Chen SH 《Optics letters》2011,36(20):4035-4037
Beam shaping of coherent laser beams is demonstrated using liquid crystal (LC) cells with optically patterned pixels. The twist angle of a nematic LC is locally set to either 0 or 90° by an alignment layer prepared via exposure to polarized UV light. The two distinct pixel types induce either no polarization rotation or a 90° polarization rotation, respectively, on a linearly polarized optical field. An LC device placed between polarizers functions as a binary transmission beam shaper with a highly improved damage threshold compared to metal beam shapers. Using a coumarin-based photoalignment layer, various devices have been fabricated and tested, with a measured single-shot nanosecond damage threshold higher than 30?J/cm2. 相似文献
2.
Magneto and Electro-Optic Intensity Modulator Based on Liquid Crystal and Magnetic Fluid Filled Photonic Crystal Fiber
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We propose a novel light intensity modulator based on magnetic fluid and liquid crystal(LC) filled photonic crystal fibers(PCFs). The influences of electric and magnetic fields on the transmission intensity are theoretically and experimentally analyzed and investigated. Both the electric and magnetic fields can manipulate the molecular arrangement of LC to array a certain angle without changing the refractive index of the LC. Therefore, light loss in the PCF varies with the electric and magnetic fields whereas the peak wavelengths remain constant. The experimental results show that the transmission intensity decreases with the increase of the electric and magnetic fields. The cut-off electric field is 0.899 V/um at 20 Hz and the cut-off magnetic field is 195 m T. This simple and compacted optical modulator will have a great prospect in sensing applications. 相似文献
3.
Ultra-narrow bandwidth optical filters consisting of one-dimensional photonic crystals with anomalous dispersion materials
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We present a new type of optical filter with an ultra-narrow bandwidth and a wide field-of-view (FOV). This kind of optical filter consists of one-dimensional photonic crystal (PC) incorporating an anomalous-dispersion-material (ADM) with, for instance, an anomalous dispersion of 6P3/2←6S1/2 hyperfine structure transition of a caesium atom. The transmission spectra of optical filters are calculated by using the transfer-matrix method. The simulation results show that the designed optical filter has a bandwidth narrower than 0.33GHz and a wide FOV of ±30°as well. The response of transmission spectrum to an external magnetic field is also investigated. 相似文献
4.
The specific features of the transmission and reflection spectra of a one-dimensional photonic crystal structure with a magnetically active layer placed between dielectric Bragg mirrors have been investigated. If the magnetic resonance frequency coincides with the frequency of the defect mode in one of the photonic bands, the defect mode in the photonic crystal can be completely suppressed, which makes it possible to effectively control the spectrum of such a structure by an external magnetic field. 相似文献
5.
采用光学传输矩阵方法,研究了外磁场作用下一维光子晶体的光传输特性.在外磁场作用下,介质介电函数在回旋频率ω.附近受到强烈的调制,使组分材料的色散关系发生明显改变,导致光子晶体的能带发生变化,透射谱出现复杂结构.在光子带隙中出现窄通带,窄带中的光是局域的.这表明,在不改变光子晶体组分材料的条件下,可以通过改变外磁场的大小,调制光子晶体的能带及其光传输性质. 相似文献
6.
V. G. Arkhipkin V. A. Gunyakov S. A. Myslivets V. P. Gerasimov V. Ya. Zyryanov S. Ya. Vetrov V. F. Shabanov 《Journal of Experimental and Theoretical Physics》2008,106(2):388-398
Transmission spectra of a one-dimensional photonic crystal (PC) formed by two multilayer dielectric mirrors and a planar oriented layer of 5CB nematic liquid crystal (LC) that is sandwiched between these mirrors and serves as a structure defect are investigated experimentally. Specific features of the behavior of the spectrum of defect modes as a function of the angle of incidence of light on the crystal are studied for two polarizations: parallel and perpendicular to the director of the LC; the director either lies in the plane of incidence or is perpendicular to it. It is shown that, for the configurations considered, the maxima of the defect modes shift toward the short-wavelength region as the tilt angle of incidence radiation increases; this tendency is more manifest for the parallel-polarized component, when the director lies in the plane of incidence. In the latter case, the width of the photonic band gap (PBG) appreciably decreases. The temperature dependence of the polarization components of the transmission spectra of a PC is investigated in the case of normal incidence of light. The spectral shift of defect modes due to the variation of the refractive index of the LC at the nematic-isotropic liquid phase transition point is measured. It is shown that, in real PCs, the amplitude of defect modes decreases when approaching the center of the band gap, as well as when the number of layers in the dielectric mirrors increases. Theoretical transmission spectra of the PCs calculated by the method of recurrence relations with regard to the decay of defect modes are in good agreement with experimental data. 相似文献
7.
Arkhipkin VG Gunyakov VA Myslivets SA Zyryanov VY Shabanov VF 《The European physical journal. E, Soft matter》2007,24(3):297-302
A one-dimensional ZrO2/SiO2 photonic crystal with a 4-n -pentyl-4' -cyanobiphenyl (5CB) nematic defect layer was used to investigate the transmission spectra of light polarized
parallel and perpendicular to the liquid-crystal director at different angles of incidence. The spectra of the photonic crystal
were shown to split into four polarized components Tij at oblique incidence. When the incident angle increased, the bandgap edges and the defect modes shifted towards short wavelengths,
while the amplitudes of the defect modes increased for the transverse magnetic polarization and decreased for the transverse
electric polarization. The observed discrepancy between the defect mode amplitudes in the center and near the edges of the
photonic bandgap was found to be related to the radiation losses inside the defect layer of a non-ideal photonic crystal.
The simulated transmission spectra obtained using recurrence relations and taking into account the decay of defect modes are
in good agreement with the experimental data. 相似文献
8.
The polarized Raman spectra of LiTbF4 have been investigated at several temperaturesT150 K, and the temperature dependence of the selfenergies of optical phonons due to the magnetoelastic interaction have been determined. The sizes of these temperature shifts, of the magnetic phonon splittings and of the level repellings between resonant optical phonons and crystal field states have been calculated using the theory of magnetoelastic interaction by Fulde and Thalmeier without any adjustable parameters, considering the modulation of the crystalline electric field by the optical phonons. The phonon modes of LiTbF4 have been determined in a rigid-ion approximation. Reasonable to good agreement with the experimental results has been obtained for most of the phonon modes. 相似文献
9.
A. H. Gevorgyan 《Optics and Spectroscopy》2017,122(5):816-825
The specific features of light transmission in a cholesteric liquid crystal (LC) cell with a director rotated by 90° have been investigated. In this structure, where a light wave is incident at a large angle with respect to the LC surface, the light is reflected (refracted) in the LC layer near the opposite boundary. It is shown that the application of an electric field changes the character of extraordinary wave refraction, as a result of which light starts passing through a cell. The transmission threshold voltage is determined, and its dependence on the angle of incidence of light is obtained. The dependence of the transmitted-light intensity on the voltage across the cell is obtained as well. The same dependences are also derived by numerical calculations with allowance for the turning points and extinction. 相似文献
10.
针对当前液晶透镜盒间隙测试存在的难题, 文中提出采用线偏振干涉法测试方法, 采用光强均匀分布的单色光入射, 检偏器的偏光轴方向与起偏器的偏光轴垂直或者平行, 液晶透镜的液晶取向层的摩擦方向与起偏器偏振轴夹角为45°, 此时干涉条纹亮暗差别最明显. 利用液晶透镜中心保持预倾角不变的透过率以及其他位置透过率最大值来计算液晶透镜的盒间隙, 该方法简单、可靠, 因采用光学手段测试, 其精确度相对较高.
关键词:
液晶透镜
盒间隙
线偏振光干涉
透过率 相似文献
11.
Y. W. Yao F. G. Wu Z. L. Hou Y. Y. Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(4):353-360
The transmission and reflection coefficients of two-dimensional semi-infinite solid-solid phononic crystal systems and fluid-fluid
phononic waveguide structures have been investigated. The numerical results show that the transmission spectra for longitudinally
and transversally polarized incident waves are different, and the spectra of the transmission and reflection coefficients
of the semi-infinite system agree well with the band structure. The numerical results show that when a guided wave incident,
localized modes are excited, and different polarities have different coupling efficiencies with the incident guided wave.
At the same time, far from the cutoff frequency, the guided wave couples out of semi-infinite waveguide highly efficiently. 相似文献
12.
In this paper, we have studied the one-dimensional photonic crystal (PC) including a magneto-optical metal defect using the developed transfer matrix method for magnetic materials. Around the two interfaces between metal and one-dimensional PC, two nonsymmetric Tamm magneto-plasmon polaritons may be excited and coupled. The coupled states take on a clear nonreciprocal behavior and result in nonreciprocal transmission. The results are demonstrated through electromagnetic field distribution simulations based on finite element software. It provides a useful reference to realize optical isolator design. 相似文献
13.
《Physics letters. A》2020,384(36):126927
We elucidate the local distribution and aggregated structure of iron oxide nanoparticles (IONPs; 6 nm in diameter) doped in the matrix of a nematic liquid crystal (LC), 4-cyano-4'-pentylbiphenyl, utilizing in situ cryogenic transmission electron microscopy and polarized light microscopy. We show that tens of IONPs aggregate into a sphere-like morphology, and the aggregates combine into elongated clusters with a length of hundreds of nm. With the IONP-doped LC matrix confined to a thin glass cell, we study the nematic-isotropic (N-I) phase transition, and suggest that local heterogeneity of LC textures as seen in polarized microscopy is caused by the existence of IONP aggregate clusters. These clusters act also as nuclei for the formation of isotropic domains upon heating. 相似文献
14.
15.
Zeeman spectra for a pure electronic transition in the emission from a crystal of CaF2 : U cooled to helium temperatures are reported for a magnetic field of 7.7 T along principal crystallographic directions. The polarized Zeeman spectra correspond to those of an E → A transition at a centre with trigonal and inversion symmetry. 相似文献
16.
Rampur S. Viswanath Philip J. Miller Charles A. Cody 《Journal of Physics and Chemistry of Solids》1979,40(3):223-229
IR transmission, near-normal IR reflection and polarized Raman spectra of single crystals of selenious acid (H2SeO3) have been obtained at temperatures between 77°K and 335°K. The observed bands in the O-H stretching region have been assigned to two types of O-H….O bonds in the crystal structure. The spectral results appear to rule out correlation field splittings, intramolecular coupling, or Fermi resonance as explanations for the observed splitting. A proposed model based on intermolecular coupling of O-H….O vibrations to explain the splitting of the O-H stretching region is given. 相似文献
17.
Homeotropically aligned nematic liquid crystals doped with azo-dye were subjected both to a linear polarized light of a He–Ne laser and to a magnetic field perpendicular to the incident light beam. We found that the emerging light was elliptically polarized when using magnetic field strengths higher than the threshold value for the magnetic Freedericksz transition. The light transmission, the rotatory power (induced by azo-dye) and the ellipticity varied quasiperiodically when increasing magnetic field strength. The number and positions of maxima and minima depend on the cell thicknesses. Changes in the phase difference between the emergent ordinary and extraordinary rays were computed from the experimental data and the magnetic field dependence of the birefringence was determined. 相似文献
18.
A NEW METHOD TO ALIGN LIQUID CRYSTAL MOLECULES BY LINEAR PHOTO-POLYMERIZATION FOR LIQUID CRYSTAL DISPLAY
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A new technique to uniformly align liquid crystal molecules is presented. The technique is based on producing an anisotropic surface on the glass substrate coated with photo-polymers by photo-polymerization of linear polarized UV-light. The orientation of liquid crystal molecules is governed by the direction of the polarized vector of UV-light. Using this method, we have studied the photo-polymer PSi-CM aligning LC 6710A molecules. The liquid crystal microscopic texture between crossed polarizers, optical retardation from liquid crystal layers and electro-optical properties of twisted nematic liquid crystal display cell are obtained, which was prepared with one side -photo-alignment and the other side-rebbed substrate. 相似文献
19.
20.
AnalysesofthePropertiesofTunableFaradayAnomalousDispersionOpticalFilterat589nmAnalysesofthePropertiesofTunableFaradayAnomalou... 相似文献