利用非规整膜系实现宽角度入射减偏振、减反射薄膜的研究

利用非均匀膜系理论对宽角度入射减偏振、减反射薄膜进行优化设计,分析了在宽角度入射的情况下,偏振光产生透过率不同的原因,选取了Na3AlF6、Ta2O5和Al2O3三种不同折射率材料,采用BK7作为基底,模拟设计了光谱区在500～560 nm波段、入射角为0~70°之间的多层减偏振、减反射薄膜,设计结果表明,薄膜的透过率得到大幅度提高.     

Surface profile optimization of antireflection gratings for solar cells

The solar cell efficiency can be improved by antireflection gratings. In this paper, the antireflection gratings with different symmetrical surface profiles are investigated by numerical simulations based on the Rigorous Coupled-Wave Analysis. Simulated results show that the antireflection performance of sharp profile such as quadratic profile has a significant improvement compared with triangular and parabolic profiles, while the top cutoff in the grating tip will severely influence the antireflection performance. Meanwhile, proper length of flat region between grating features in the nonclose-packed triangular antireflection grating can have better antireflection performance than the close-packed counterpart for the same grating period and height. Such antireflection gratings with different surface profiles may offer attractive solutions to current commercial silicon solar cell, as well as organic and other semiconductor material based solar cells.     

Conversion efficiency enhanced photovoltaic device with nanohole arrays in antireflection coating layer

In this paper, the authors introduce an enhanced photovoltaic device with nanohole arrays only in its antireflection coating. These nanoholes can improve light trapping efficiency as well as photoelectric conversion efficiency of the device. The authors analyze the light absorption of the devices with nanohole arrays by Finite-Difference Time Domain method and calculate the photoelectric conversion efficiency. The results show that the nanohole arrays can improve the light trapping more efficiently than the Si₃N₄ antireflection coating, especially, in 400-600 nm spectral range. Nanohole arrays with different characteristic parameters were fabricated in the antireflection coating layer of a Φ200 μm Si detector by using focused-ion beam system. With the optimized nanohole arrays, the enhancements factor of the experimental sample's photoelectric conversion efficiency is ~ 16% within the 400-600 nm spectral range and ~ 10% within the 400-1100 nm spectral range.     

Sol-gel preparation and characterization of nanoporous ZnO/SiO2 coatings with broadband antireflection properties

Nanoporous ZnO/SiO₂ bilayer coatings were prepared on the surface of glass substrates via sol-gel dip-coating process. The structural, morphological and optical properties of the coatings were characterized. The refractive indices of ZnO layer and SiO₂ layer are 1.34 and 1.21 at 550 nm, respectively. The transmittance and reflectance spectra of the coatings were investigated and the broadband antireflection performance of the bilayer structure was determined over the solar spectrum. The solar transmittances in the range of 300-1200 nm and 1200-2500 nm are increased by 6.5% and 6.2%, respectively. The improvement of transmittance is attributed to the destructive interference of light reflected from interfaces between the different refractive-index layers with an optimized thickness. Such antireflection coatings of ZnO/SiO₂ provide a promising route for solar energy applications.     

Subwavelength structures for high power laser antireflection application on fused silica by one-step reactive ion etching

In this paper we report a simple method to fabricate a novel subwavelength structure surface on fused silica substrate using one-step reactive ion etching with two-dimensional polystyrene colloidal crystals as masks. The etching process and the morphologies of the obtained structure are controlled. We show that the period of the obtained fused silica pillar-like arrays were determined by the initial polystyrene nanoparticle size. The height of pillar arrays can be adjusted by controlling the etching duration, which is proved to be of importance in tailoring the antireflection properties of subwavelength structures surface. The novel subwavelength structures surface exhibit excellent broadband antireflection properties, but the size of the pillar affects the antireflective properties in short wavelength region. We anticipate this method would offer a convenient and scalable way for inexpensive and high-efficiency high power laser field designs.     

可见光波段及1 064 nm波长处用于Glan-Taylor棱镜减反射膜

为了提高Glan-Taylor棱镜的透射率,研究了Glan-Taylor棱镜在可见光波段及1 064 nm波长处减反射膜膜的设计和制备.为提高薄膜和冰洲石晶体的附着力,采用沉积Al2O3为过渡层,ZrO2作缓冲层的方法,用单纯形优化的方法进行膜系优化设计.用电子束沉积和离子束辅助沉积的方法制备了多层减反射膜,并采用石英晶体振荡法监控膜厚和沉积速率.测量结果表明,在可见光波段及1 064 nm波长处的剩余反射率均小于0.5%经测试薄膜与冰洲石晶体的附着力性能良好.     

银镜反应制备纳米蛾眼减反结构法

为了降低光学表面的菲涅耳反射,提出了一种制备仿生减反结构的方法.利用银镜反应并结合退火处理在硬性材质基底表面制备银纳米粒子,经反应离子刻蚀工艺,在基底表面形成一层纳米蛾眼减反结构.分析了周期分布和随机分布纳米蛾眼的光学特性,实验研究了退火参量和刻蚀参量对银纳米颗粒直径、密度以及高度的影响,并在硅和石英基底上分别制备了随机减反结构.测试结果表明:硅基平均反射率小于4.5%,双面石英基透过率达98.1%.理论和实验均表明:随机分布的纳米仿生蛾眼结构具有宽光谱、广视角和高减反特性,所提出的制备方法具有简便易行、低成本、大幅面等优点,在光电器件中具有良好的潜在应用前景.     

Antireflection film in one-dimensional metallo-dielectric photonic crystals

We calculated the transmittance of a one-dimensional (1D) metallo-dielectric photonic crystal (MDPC) in the optical region including the absorption losses in metal layers. The structure consists of five Ag and four GaN layers stacked alternately. When we add an antireflection coating to each end of the stack, the transmittance of the MDPC is increased twice as much and the oscillations in the transmission spectrum are also smoothed out compared with the case without them. The transmittance for oblique incident angles is also increased by the addition of two antireflection layers at the ends of the 1D MDPC.     

Modelling of a two-dimensional photonic crystal as an antireflection coating for optoelectronic applications

In article a two-dimensional photonic crystal (PhC) is considered and modelled as a new generation antireflection coating for optoelectronic devices. Traditional antireflective coatings (ARCs) reduce the reflection of the radiation only – the new generation of antireflective coatings should affect the distribution of the radiation also. Such functionality can be provided by the two-dimensional PhC which reduce the reflection and scatter transmitted light. Prior to the fabrication, the PhCs should be designed and analysed. Results of the analysis should provide quantitative means for choice of materials and design solutions. In work, we analyse the electromagnetic field distribution as Poynting vectors inside the materials of optoelectronic devices, in order to investigate the possibility of improving the construction of future optoelectronic devices. Furthermore, we calculate the reflection and transmission of that ARC. It’s a complex optic analysis of new generation of ARC. The numerical analysis has been performed with the FDTD method in Lumerical Software. In work, we consider the two-dimensional photonic crystal on the top surface of optoelectronic structures. We compared the results with the traditional ARC from these same parameters as PhC: thickness and material. As an example, we presented the application of modelled, photonic crystal, thin-film, GaAs solar cells with PhC on top. The efficiency of this solar cell, using the photonic crystal, was improved by 6.3% over the efficiency of this same solar cell without PhC. Thus, our research strongly suggests that the unique properties of the photonic crystal could be used as a new generation of ARC.