共查询到20条相似文献,搜索用时 48 毫秒
1.
利用傅里叶模式理论分析了TE波自准直角入射的使用条件下,多层介质膜光栅的光栅区和多层膜区电场分布的特点.分别讨论了HfO2和SiO2为顶层光栅材料时,光栅结构参数对光栅脊峰值电场的影响,结果表明,对于不同膜厚的顶层材料,存在一个最佳膜厚度,使光栅脊峰值电场最小,并且当膜厚增大时,设计大高宽比的光栅可以降低该电场峰值.最后,在大角度条件下使用多层膜光栅也可以降低光栅脊处的峰值电场.
关键词:
衍射光学
多层介质膜光栅
模式理论
损伤阈值 相似文献
2.
Design of High-Efficiency Diffraction Gratings Based on Rigorous Coupled-Wave Analysis for 800nm Wavelength 下载免费PDF全文
We report on the design of a high diffraction efficiency multi-layer dielectric grating with wide incident angle and broad bandwidth for 80Ohm. The optimized grating can achieve 〉 95% diffraction efficiency in the first order at an incident angle of 5° from Littrow and a wavelength from 77Ohm to 83Ohm, with peak diffraction efieieney of 〉 99.5% at 80Ohm. The electric field distribution of the optimized multi-layer dielectric grating within the gratings ridge is 1.3 times enhancement of the incidence light, which presents potential high laser resistance ability. Because of its high-effieieney, wide incident, broad bandwidth and potential high resistance ability, the multi-layer dielectric grating should have practical application in Ti:sapphire laser systems. 相似文献
3.
Heyuan Guan Yunxia Jin Shijie Liu Fanyu Kong Yin Du Kai He Kui Yi Jianda Shao 《Applied physics. B, Lasers and optics》2014,114(4):557-565
Metal multi-layer dielectric gratings (MMDG) for pulse compressors in high-energy laser systems should provide broad bandwidth as well as high laser-induced damage thresholds. The non-uniform optical near-field distribution of MMDG is an important factor that limits damage resistant capabilities. MMDG for pulse compressors operating at 800 nm with a corrugated SiO2 layer are designed by using a genetic algorithm and the Fourier mode method. The diffraction efficiency, bandwidth, and near-field distribution of the MMDG are theoretically investigated. For the single dielectric match layer grating, the bandwidth is 140 nm, if the thickness and refractive index of the match layer are changed, the maximum electric field in the grating ridge, match layer, and metal layer of the grating increases with the decrease in grating diffraction efficiency. For the multi-dielectric match layer grating, the bandwidth and the maximum electric field in the metal layer decrease with the increase in high- and low-index material pairs, and the maximum electric field in the grating ridge and match layer initially decreases and then increases. Over a wide wavelength range, the maximum electric field in the grating ridge, match layer, and metal layer is minimal near the central wavelength. Moreover, MMDG should be used at larger incident angles while keeping enough bandwidth to reduce the electric field in the grating. 相似文献
4.
Shijie Liu Jianyong Ma Chaoyang Wei Zicai Shen Jianbin Huang Jianda Shao 《Optics Communications》2007,273(1):290-295
We present designs of high-efficiency compression grating based on total internal reflection (TIR) for picosecond pulse laser at 1053 nm. The setup is devised by directly etching gratings into the bottom side of a prism so that light can successfully enter (or exit) the compression grating. Dependence of the −1 order diffraction efficiencies on the constructive parameters is analyzed for TE- and TM-polarized incident light at Littrow angle by using Fourier modal method in order to obtain optimal grating structure. The electric field enhancement within the high-efficiency TIR gratings is regarded as another criterion to optimize the structure of the TIR gratings. With the criterion of high diffraction efficiency, low electric field enhancement and sufficient manufacturing latitude, TIR compression gratings with optimized constructive parameters are obtained for TE- and TM-polarized incident light, respectively. The grating for TE-polarized light exhibits diffraction efficiencies higher than 0.95 within 23 nm bandwidth and relatively low square of electric field enhancement ratio of 5.7. Regardless of the internal electric field enhancement, the grating for TM-polarized light provides diffraction efficiencies higher than 0.95 within 42 nm bandwidth. With compact structure, such TIR compression gratings made solely of fused silica should be of great interest for application to chirped pulse amplification (CPA) systems. 相似文献
5.
用于展宽和压缩激光脉冲的多层膜脉宽压缩光栅是由多层介质高反膜和位于其顶层的浮雕光栅构成。以设计的高反射多层膜为基础,利用傅里叶模式理论分析了其衍射场分布,给出了TE波自准直角入射的使用条件下,多层介质膜脉宽压缩光栅衍射效率的表达式。以-1级衍射效率为评价函数,分别讨论了HfO2和SiO2为顶层材料时,多层膜脉宽压缩光栅-1级衍射效率高于0.95的光栅结构参量范围。结果表明,在该条件下,选择HfO2为顶层材料时,光栅结构参量有较大的取值范围。给出了优化的光栅结构参量,并分析了光栅制作误差及其使用条件的宽容度,对光栅制作工艺和使用具有一定的指导意义。 相似文献
6.
Shijie Liu Jianyong Ma Zicai Shen Yunxia Jin Zhengxiu Fan 《Applied Surface Science》2007,253(7):3642-3648
Thin-film design used to fabricate multi-layer dielectric (MLD) gratings should provide high transmittance during holography exposure, high reflectance at use wavelength and sufficient manufacturing latitude of the grating design making the MLD grating achieve both high diffraction efficiency and low electric field enhancement. Based on a (HLL)9H design comprising of quarter-waves of high-index material and half-waves of low-index material, we obtain an optimum MLD coating meeting these requirements by inserting a matching layer being half a quarter-wave of Al2O3 between the initial design and an optimized HfO2 top layer. The optimized MLD coatings exhibits a low reflectance of 0.017% under photoresist at the exposure angle of 17.8° for 413 nm light and a high reflectance of 99.61% under air at the use angle of 51.2° for 1053 nm light. Numerical calculation of intensity distribution in the photoresist coated on the MLD film during exposure shows that standing-wave patterns are greatly minimized and thus simulation profile of photoresist gratings after development demonstrates smoother shapes with lower roughness. Furthermore, a MLD gratings with grooves etched into the top layer of this MLD coating provides a high diffraction efficiency of 99.5% and a low electric field enhancement ratio of 1.53. This thin-film design shows perfect performances and can be easily fabricated by e-beam evaporation. 相似文献
7.
8.
The intermediate regime of light diffraction on acoustophotorefractive holographic gratings written in cubic photorefractive crystals according to the synchronous-detection mechanism is studied. It is shown that the diffraction efficiency in sillenite-type gyrotropic crystals only slightly depends on the incident light polarization and the external electric field. The highest diffraction efficiency in nongyrotropic crystals was achieved for p-polarized writing and reading light and at a considerable external electric field strength. 相似文献
9.
We report the fabrication of efficient, buried diffraction gratings and micro-craters in bulk polystyrene using femtosecond laser direct writing technique. We recorded a maximum diffraction efficiency of 10% for a buried grating fabricated at 1 μJ energy, 1 mm/s speed, and a period of 30 μm. Buried micro-craters, with typical dimensions of ∼2 μm, were achieved at low energies and high scanning speeds. From the field emission scanning electron microscope studies, the observed emission is attributed as due to the inner surface modifications and the debris settled around the voids. The fabricated gratings subjected to heat treatment were tested for the diffraction efficiency and emission at different excitation wavelengths and the observed results are presented. Raman spectra collected from the femtosecond laser modified regions revealed the disappearance of few Raman modes at high peak intensities associated with incident Gaussian laser pulse. Potential applications of these luminescent micro-craters are highlighted. 相似文献
10.
Numerical simulation of the modulation to incident laser by the repaired damage site in a fused silica subsurface 下载免费PDF全文
One of the main factors of laser induced damage is the modulation to incident laser which is caused by the defect in the subsurface of the fused silica.In this work,the repaired damage site irradiated by CO 2 laser is simplified to a Gaussian rotation according to the corresponding experimental results.Then,the three-dimensional finite-difference time-domain method is employed to simulate the electric field intensity distribution in the vicinity of this kind of defect in fused silica front subsurface.The simulated results show that the modulation is notable,the E max is about 2.6 times the irradiated electric field intensity in the fused silica with the damage site (the width is 1.5 μm and depth is 2.3 μm) though the damage site is repaired by CO 2 laser.The phenomenon and the theoretical result of the annular laser enhancement existed on the rear surface are first verified effectively,which agrees well with the corresponding experimental results.The relations between the maximal electric field intensity in fused silica with defect depth and width are given respectively.Meanwhile,the corresponding physical mechanism is analysed theoretically in detail. 相似文献
11.
This paper presents a more detailed interaction of an electromagnetics light with a metallic surface-relief subwavelength grating utilizing the rigorous coupled-wave analysis. The focus of this work is the accurate modeling of undetermined aspects of diffraction patterns produced by binary metallic grating structures, specially gold grating. First-order diffraction efficiency for rectangular-groove gold grating with equal groove and ridge widths are presented for various wavelengths as a function of period, groove depth, polarization and angle of incidence. We also studied diffraction efficiency of both of TE and TM polarization modes against increasing of incident angle as well as TE polarization against increment of grating period. As a result, very low reflectivity at zero-order was found out for TE and TM polarizations at the pitch of Λ = 2λ. Having been studied diffraction efficiency of metallic surface-relief gratings, we also examined polarization-dependent efficiency of diffraction orders, for different groove depths. Simulation results have been completely presented. 相似文献
12.
13.
T. N. Smirnova O. V. Sakhno V. I. Bezrodnyj J. Stumpe 《Applied physics. B, Lasers and optics》2005,80(8):947-951
In this letter we report a simple technique to produce volume holographic gratings based on photopolymerizable composites containing TiO2 nanoparticles. Diffraction gratings with high refractive index modulation amplitude (up to 1.25 × 10−2) have been formed due to the periodic distribution of high refractive index nanoparticles in a low refractive index polymer matrix. The diffraction efficiency increases strongly on increasing the nanoparticle concentration. Taking the mixture with 10 wt.% TiO2 nanoparticles, gratings with high diffraction efficiency, low level of scattering and high transparency in the visible-wavelength range have been obtained. This will ultimately lead to different applications of diffractive optical elements based on nanocomposites. The dependence of the gratings’ diffraction efficiency on the intensity of probe laser pulses at 1064 nm has been explored. It is shown that the nonlinear response of the gratings is attributed mainly to the nonlinear properties of the TiO2 nanoparticles embedded in the polymer matrix. The mechanism of the grating formation and the reasons for the nonlinear behavior of the diffraction efficiency are discussed. 相似文献
14.
15.
Theoretical and experimental research on spectral performance and laser induced damage of Brewster's thin film polarizers 总被引:1,自引:0,他引:1
Polarizers respectively with broad polarizing region bandwidth, large layer thickness error tolerance and high extinction ratio are designed and prepared. Transmittance spectra of the prepared samples are measured at Brewster's angle, and the results show that different requirements can be fulfilled by optimized designs. Spectral performance of designs with higher layer thickness error tolerance coincides better with the theoretical spectra. Laser induced damage threshold of the prepared samples are evaluated. Electric field distribution, defect, film absorption, and damage morphology are investigated, and the results indicate that electric field distribution in high index layers is the main reason that causes the difference of laser induced damage threshold. For both p polarized and s polarized light, the lower the electric field peak value and the farther the layer, which has the strongest electric field away from air, the higher the laser induced damage threshold. 相似文献
16.
D.G. Papazoglou N.C. Deliolanis A.G. Apostolidis E.D. Vanidhis 《Applied physics. B, Lasers and optics》2000,71(6):841-848
We study the diffraction efficiency of volume phase gratings in Bi12GeO20, when the grating vector, lying on a (111) plane, is at an angle with respect to the crystallographic direction. An external
bias field parallel to the direction is applied during recording, thus, the recording conditions depend on the grating vector
orientation. The basic parameters determining the diffraction efficiency are the grating vector orientation, the rotatory
power and the field-induced linear birefringence (primary and secondary). Analytic expressions for the diffraction efficiency
have been obtained by taking into account all the above-mentioned parameters, provided that linearly polarized light is incident
on the crystal. In this configuration, the influence of the secondary electro-optic effect (inverse piezoelectric and photoelastic
effects) to the diffraction efficiency is actually stronger than the influence of the primary effect. Experimental results
are given.
Received: 3 January 2000 / Revised version: 6 June 2000 / Published online: 13 September 2000 相似文献
17.
18.
基于严格耦合波理论建立了多层介质膜光栅的衍射机理模型,给出了TE波自准直条件下多层介质膜光栅衍射效率的表达式.以-1级衍射效率为评价函数,分析了表面浮雕结构分别为HfO2和SiO2材料的介质膜光栅获得衍射效率优于96%的结构参数.数值计算表明,顶层材料为HfO2的介质膜光栅具有更宽的结构选择范围.最后分析了介质膜光栅的制备容差和允许的入射角度范围.
关键词:
衍射效率
多层介质膜光栅
严格耦合波理论 相似文献
19.
20.
为了克服目前高能短脉冲装置压缩光栅的损伤阈值无法满足要求的问题,针对星光Ⅲ装置皮秒激光束的压缩器,设计了由熔石英材料构成的、具有较高损伤阈值的光子晶体光栅,该光栅由2维光子晶体和表面光栅结构两部分组成,具有高反射效率和强角色散的能力。计算结果显示:经过优化设计的光子晶体光栅在波长1 053 nm,57°~77°的入射范围内,-1级衍射效率超过了92%,而当入射角为71°时,在1 040~1 090 nm光谱范围内,-1级衍射效率超过92%,性能满足使用要求。 相似文献