Simple and universal method in designs of high-efficiency diffractive optical elements for spectrum separation and beam concentration

Diffractive optical elements（DOEs） with spectrum separation and beam concentration（SSBC） functions have important applications in solar cell systems. With the SSBC DOEs, the sunlight radiation is divided into several wave bands so as to be effectively absorbed by photovoltaic materials with different band gaps. A new method is proposed for designing high-efficiency SSBC DOEs, which is physically simple, numerically fast, and universally applicable. The SSBC DOEs are designed by the new design method, and their performances are analyzed by the Fresnel diffraction integral method.The new design method takes two advantages over the previous design method. Firstly, the optical focusing efficiency is heightened by up to 10%. Secondly, focal positions of all the designed wavelengths can be designated arbitrarily and independently. It is believed that the designed SSBC DOEs should have practical applications to solar cell systems.

A single diffractive optical element implementing spectrum-splitting and beam-concentration functions simultaneously with high diffraction efficiency

In this paper,a novel method is proposed and employed to design a single diffractive optical element（DOE） for implementing spectrum-splitting and beam-concentration（SSBC） functions simultaneously.We develop an optimization algorithm,through which the SSBC DOE can be optimized within an arbitrary thickness range according to the limitations of modern photolithography technology.Theoretical simulation results reveal that the designed SSBC DOE has a high optical focusing efficiency.It is expected that the designed SSBC DOE should have practical applications in high-efficiency solar cell systems.

Realizing high photovoltaic efficiency with parallel multijunction solar cells based on spectrum-splitting and-concentrating diffractive optical element

Based on the facts that multijunction solar cells can increase the efficiency and concentration can reduce the cost dramatically, a special design of parallel multijunction solar cells was presented. The design employed a diffractive optical element （DOE） to split and concentrate the sunlight. A rainbow region and a zero-order diffraction region were generated on the output plane where solar cells with corresponding band gaps were placed. An analytical expression of the light intensity distribution on the output plane of the special DOE was deduced, and the limiting photovoltaic efficiency of such parallel multijunction solar ceils was obtained based on Shockley-Queisser＇s theory. An efficiency exceeding the Shockley--Queisser limit （33%） can be expected using multijunction solar cells consisting of separately fabricated subcells. The results provide an important alternative approach to realize high photovoltaic efficiency without the need for expensive epitaxial technology widely used in tandem solar cells, thus stimulating the research and application of high efficiency and low cost solar cells.

Design optimization of highly efficient spectrum-splitting and beam-concentrating diffractive optical element for lateral multijunction solar cells

Two improved algorithms are proposed to extend a diffractive optical element （DOE） to work under the broad spec- trum of sunlight. An optimum design has been found for the DOE, with a weighted average optical efficiency of about 6.8% better than that of the previous design. The optimization of designing high optical efficiency DOEs will pave the way for future designs of high-efficiency, low-cost lateral multijunction solar cells based on such a DOE.

Spectrum-Splitting Diffractive Optical Element of High Concentration Factor and High Optical Efficiency for Three-Junction Photovoltaics

A spectrum-splitting and beam-concentrating （SSBC） diffractive optical element （DOE） for three-junction pho- tovoltaics （PV） system is designed and fabricated by five-circ/e micro-fabrication. The incident solar light is efficiently split into three sub-spectrum ranges and strongly concentrated on the focal plane, which can be di- rectly utilized by suitable spectrum-matching solar cells. The system concentration factor reaches 12x. Moreover, the designed wavelengths （450nm, 550nm and 65Onto） are spatially distributed on the focal plane, in good agree- ment with the theoretical results. The average optical effic/ency of all the cells over the three designed wavelengths is 60.07%. The SSBC DOE with a high concentration factor and a high optical efficiency provides a cost-effective approach to achieve higher PV conversion efficieneies.

Subwavelength Diffractive Optical Elements

1 Introduction 1.1 Advantages of DOE 1)High diffraction efficiency; 2)Dispersive; 3)More selectivity of designing parameters; 4)More selectivity of primary materials; 5)Can make components miniature,forming array and integration. 1.2 1.3 megapixel triplet plastic mobile

Design of Diffractive Optical Elements Used for Beam Shaping in the Fresnel Domain

In the Fresnel transform domain, an effective improvement to the conventional iterative algorithm for designing the diffractive optical elements (DOEs) used for spatial beam shaping has been proposed. The algorithm can successfully achieve to design DOEs for beam shaping. Compared with conventional algorithm, this algorithm can provide faster convergence, more powerful ability to overcome local minimum problem and better shaping quality. By computer simulation, the result has shown that the DOEs designed by this algorithm has snch advantages as high uniformity at the main lobe, low profile error and steep edge.

Diffractive optical elements 75 years on:from micro-optics to metasurfaces

Diffractive optical elements(DOEs)are intricately designed devices with the purpose of manipulating light fields by precisely modifying their wavefronts.The concept of DOEs has its origins dating back to 1948 when D.Gabor first introduced holography.Subsequently,researchers introduced binary optical elements(BOEs),including computer-generated holograms(CGHs),as a distinct category within the realm of DOEs.This was the first revolution in optical devices.The next major breakthrough in light field manipulation occurred during the early 21st century,marked by the advent of metamaterials and metasurfaces.Metasurfaces are particularly appealing due to their ultra-thin,ultra-compact properties and their capacity to exert precise control over virtually every aspect of light fields,including amplitude,phase,polarization,wavelength/frequency,angular momentum,etc.The advancement of light field manipulation with micro/nano-structures has also enabled various applications in fields such as information acquisition,transmission,storage,processing,and display.In this review,we cover the fundamental science,cutting-edge technologies,and wide-ranging applications associated with micro/nano-scale optical devices for regulating light fields.We also delve into the prevailing challenges in the pursuit of developing viable technology for real-world applications.Furthermore,we offer insights into potential future research trends and directions within the realm of light field manipulation.

3D Diffractive Focusing THz of In-Plane Surface Plasmon Polarition Waves

Demonstrated that analog of diffractive and refractive 3D optics in free space can be developed to manipulate surface waves such as surface plasmon polaritons (SPPs). It has been shown that an air-gap control of a floating dielectric block can generate the dynamic phase and amplitude modulation of the SPP transmission coefficient. Unlike conventional bulk optics, the nano-scale surface optics for SPP processing contains several unexpected and interesting features in addition to the physical features described. Dynamic plasmonic information processing on the nano-scale using air-gap control may be an effective mechanism for building a dynamic plasmonic information processing system.

基于衍射透镜接收的激光雷达特性分析及测试

在激光雷达系统设计中,光学系统的优化与设计是一个重要的研究方向,本文利用衍射光学元件(DOE)的设计自由度高和色散大等优势,将DOE用于激光雷达接收端,同时实现聚焦和滤光作用,降低了光学系统复杂度。本文基于DOE的原理,仿真分析了DOE的光学特性,并且以DOE作为激光雷达的光学接收端,完成了激光雷达测距实验,证明了DOE同时具有聚焦作用和窄带滤光作用,实验结果与仿真基本一致。本文利用DOE在激光雷达中的优势,实现激光雷达的轻量化、集成化和高效化。

Full Complex Amplitude Digital Holograms： Design, Fabrication and Optical Characterization

Diffractive optical elements have a large number of industrial applications, such as beam shaping and optical filtering. Traditionally, these elements modulate the phase of the incoming light or its amplitude, but not both. To overcome this limitation, full complex-amplitude modulation diffractive optical elements were developed. Well-established integrated circuit fabrication steps were employed to fabricate the devices with high precision. Using this approach, the new element's optical performances are improved also for near field operations. With this device it is possible to obtain 100% efficient spatial filtering and low noise reconstructed images.

广角衍射光学元件的优化设计

为进一步研究入射角度的增大对衍射光学元件(diffractive optical element,DOE)衍射效率及微结构高度等参数的影响,分析了入射角度和周期宽度对带宽积分平均衍射效率的影响。基于扩展标量衍射理论,建立了DOE的微结构高度与入射角度和周期宽度的数学模型,提出了工作在一定入射角度范围内,基于复合带宽积分平均衍射效率(comprehensive polychromatic integral diffraction efficiency,CPIDE)最大化实现设计波长和微结构高度等结构参数的优化设计方法。以工作在红外波段的DOE为例进行分析。结果表明:当相对周期宽度为20,入射角度范围为0°~40°时,该DOE的CPIDE为94.15%,微结构高度为1.3396mm。该设计方法可以实现广角DOE的优化设计。

Design of refractive/diffractive hybrid optical elements for beam shaping with large diffraction pattern

Diffractive optics is an important technique for beam shaping with high light efficiency and strong diffraction pattern flexibility. Since the diffraction angle is limited by the unit size of the diffractive optical element （DOE）, the size of the required diffraction pattern is always rather small. In this Letter, refractive/diffractive hybrid optical elements （RDHOEs） consisting of a DOE and a lens are used to realize beam shaping for a large diffraction pattern. The lens, as the component of the RDHOEs, can not only be concave but also convex, and the double sampling Fresnel diffraction algorithm is developed for the design of these two types of RDHOEs. The simulation and experimental results provide solid evidence to demonstrate the proposed method with the pure phase spatial light modulator.

End-to-end optimization of a diffractive optical element and aberration correction for integral imaging

In the integral imaging light field display, the introduction of a diffractive optical element (DOE) can solve the problem of limited depth of field of the traditional lens. However, the strong aberration of the DOE significantly reduces the final display quality. Thus, herein, an end-to-end joint optimization method for optimizing DOE and aberration correction is proposed. The DOE model is established using thickness as the variable, and a deep learning network is built to preprocess the composite image loaded on the display panel. The simulation results show that the peak signal to noise ratio value of the optimized image increases by 8 dB, which confirms that the end-to-end joint optimization method can effectively reduce the aberration problem.

Diffractive Optical Elements for Dynamic Optical Coupling

Diffractive optical elements such as the complementary Dammann gratings are incorporated for dynamic optical fiber splitting and combining. Experimental results of 1×8 dynamic optical couplings are presented.

高亮度低色差裸眼三维显示中的谐衍射结构设计

目前,裸眼3D显示技术仍存在亮度低、清晰度差、结构复杂和制造难度高等缺点。为此,提出了一种可同时精确调制RGB像素光线的具有较大周期宽度的离散化谐衍射结构,四组交织排列的谐衍射结构子单元旋转对称分布组成调制三维光场的位相调制面板。使用Tracepro软件对水平方向上两个特定位置处的体像素进行了分光模拟实验。分析了不同台阶近似以及光源斜入射时的衍射效率与总光效的关系,得到16台阶近似时入射角应小于10°的结论。设计的谐衍射结构提升了显示亮度和清晰度,降低了设计与制造难度。得到了一种具有两个观看视角、分离角度为9.4°、最佳观看位置距离屏幕为384.2~402.8mm的裸眼3D显示方案。

Correction of dispersion distortion of femtosecond pulses by using the non-planar surface of diffractive optical elements

Peculiarities of propagation of femtosecond pulses through a focusing diffractive optical element (DOE) are considered. It is shown that the time delay between the pulse and phase wavefronts can be decreased by fabricating the DOE on the optimal curvilinear surface.

制冷型折衍混合双波段红外光学系统设计

能够同时工作在中波红外和长波红外频谱范围内的双波段红外光学系统可以有效利用这两个波段的信息,实现优势互补,从而显著提升其探测性能,应用前景广阔。双层谐衍射光学元件不仅具备独特的色散特性,还可以在多个设计波长处获得很高的衍射效率,为双波段红外光学系统设计提供了新思路。针对双层谐衍射光学元件的相关理论进行了研究,并基于双层谐衍射光学元件完成了焦距为200 mm,F数为2的制冷型折衍混合双波段红外光学系统的设计。成像质量分析以及冷反射分析结果表明,所设计光学系统的各类像差得到了有效校正,成像质量优良。

双程色散声光可调谐滤波器设计

声光可调谐滤波器(Acousto-Optic Tunable Filter,AOTF)是一种基于声光效应的色散器件,通过改变超声频率的大小,可以使光的衍射方向发生变化,从而进行波长选择。本研究设计了一种新的双程色散AOTF结构,并利用有限元分析软件对其滤波特性展开研究。研究结果表明,这种双程色散AOTF的设计可以有效地压缩光谱线宽,当中心波长为1064 nm时,在超声工作频率为84 MHz的情况下,线宽压缩效率达到了28.6%,明显提高了光谱分辨率;同时,这种结构还具有较强的抑制旁瓣效果,可以将中心波长为1064 nm的衍射光的旁瓣从-27.0 dB压缩至-44.8 dB,提高了光谱纯净度。

Laser beam characteristic for laser resonators with diffraction optical elements

The matrix eigenvalue method is used to analyze a laser resonator composed of diffraction optical elements. The results show that this type of resonator can separate fundamental mode and high order modes effectively. The output beams can be designed for different requests.