bluuebunny/crossref_metadata_2025 huggingface dataset:
Blazed Diffractive Optics
Authors: Fleming Madeleine B.
Published: February 2023

The diffractive optics community has embraced the lithographic methods used in the electronics industry1. Typically, binary transmission masks are used to expose resist and produce stepped structures which approximate the ideal, continuous profiles. Since these profiles are approximations of the ideal, continuous profiles, the diffraction efficiency is less than 100%: in theory, a four-level DOE has a first-order efficiency of 81%; an 8-level DOE, 95%1. Although the efficiency can be increased by increasing the number of levels and computer-based optimization, the process is limited by the resolutions of the binary masks and of the mask registration to the substrate.
Imaging in planar optics: system design for oblique deflection angles
Authors: Testorf Markus , Jahns Jürgen
Published: February 2023

Planar optics has been successfully demonstrated to be useful for the integration of free space optical systems1. In this context, planar integration means the arrangement of optical elements on the surface of a thick transparent substrate. The light signal travels within the substrate along a folded zig-zag path, reflected at its surfaces. Since planar optics was first proposed, various applications has been demonstrated like array generation2 or imaging3.
Diffractive Optical Element for Chromatic Confocal Imaging
Authors: Dobson Sarah L. , Sun Pang-chen , Fainman Yeshayahu
Published: February 2023

Confocal scanning imaging technique is attractive for various microscopic imaging applications due to its superior resolution, rejection of scattered light, and depth discrimination [1-3]. This method attracted special interest in such applications as imaging biological and semiconductor materials, where high definition in both the transverse and longitudinal dimensions is required. The unique property of the depth discrimination enables the confocal microscope to measure the depth image of a 3-D object by moving different parts of the object transversally and longitudinally into the focal region. The precision of the depth measurement depends on the depth Point-Spread-Function (PSF) of the confocal imaging system as well as the depth resolution of the depth scanning device. To achieve high depth resolution, most of the existing confocal imaging systems use a high precision and very stable mechanical scanning methods. In contrast, chromatic confocal microscope alleviates the requirement of the mechanical depth scanning by employing a broadband light source (e.g., white light source) and a dispersive objective lens for wavelength-depth coding [2-4]. With this method different spectral components of the source are focused onto different depth planes of the object, and the measured output power spectrum is directly translated into the depth information of the object. Furthermore, the chromatic confocal microscope can perform parallel depth measurements when the output power spectrum components are detected and analyzed in parallel.
Tunable Diffractive Optical Filter for Imaging Applications
Authors: Cox J. Allen , Fritz Bernard S.
Published: February 2023

Remote detection and monitoring of scenes, objects, and materials in selective spectral bands is an increasingly important field with many applications. A variety of optical filtering concepts have been suggested for the sensors used for this purpose, ranging from fixed dielectric filters and rotating filter wheels to more advanced techniques based on acousto-optical gratings and interferometric devices (Fabry-Perot and Michelson). These latter methods (acousto-optic and interferometric) have been demonstrated(1,2) and have shown the value provided by tunability and spectral agility in the optical filter. More recently, methods based on diffractive optics have been proposed for tunable spectral filtering. Specifically, the large degree of longitudinal dispersion in a diffractive element has been exploited both by Hinnrichs and Morris(3) and by the authors(4).
Diffractive Optics Technology for F-Θ Scan Lenses
Authors: McIntyre Kevin J. , Morris G. Michael
Published: February 2023

A variety of optical systems utilize F-θ lenses to focus a scanned laser beam to a small spot. Typical applications include laser printing and laser machining. Since scan lenses usually operate at discrete laser wavelengths, diffractive optical components can be incorporated into these designs without the efficiency losses normally associated with broadband applications. This paper will examine the use of diffractive optical elements in F-θ scan lens design. A discussion of some basic design principles is provided. This is followed by a comparison between a refractive system and a hybrid system which illustrates how diffractive optics can significantly enhance the performance of F-θ scan lenses.
A Rogues’ Gallery of CGH Null Tests
Authors: Arnold Steven
Published: February 2023

CGH null testing of aspheric optics was first demonstrated by MacGovern and Wyant in 1971 but has only recently become available as a commercial product. This talk describes a variety of CGH null test configurations using both commercial and customized interferometers. Several of the aspheres and their associated CGH nulls will be shown to exhibit various pathological traits.
Rigorous Design of Flat-Top Generators
Authors: Kuittinen Markku , Turunen Jari , Vahimaa Pasi
Published: February 2023

One of the most common tasks in beam shaping is the transformation of a Gaussian laser beam into a uniform far-field distribution. We present both non-periodic and periodic resonance-region structures that convert a narrow beam (waist size of the order of the wavelength) into a nearly flat-top distribution over a wide angular range.
Diffraction Efficiency of High-NA Continuous-Relief Diffractive Lenses
Authors: Rossi M. , Blough C.G. , Raguin D.H. , Popov E.K. , Maystre D.
Published: February 2023

Diffractive lenses are key elements in a large variety of optical systems. In hybrid refractive/diffractive optical systems they are used as powerful elements for aberration correction. Other applications, such as fiber coupling and optoelectronic devices, benefit from the fact that diffractive structures are thin and lightweight, enabling very compact systems. In addition, low-cost replication processes with a high profile fidelity make the use of diffractive lenses in prototype systems as well as in volume production very attractive.
Analysis and synthesis of 2-D diffractive lens using the local linear grating model and the coupled-wave theory
Authors: Sheng Yunlong , Larochelle Simon , Feng Dazeng
Published: February 2023

Large numerical aperture diffractive lenses have many applications for imaging and beam coupling. Since the minimum Fresnel zone width of a diffractive lens is approximately proportional to F-number: rM - rM-1 = 2λF/#, the grating period in the region close to the lens edge is comparable with the wavelength λ, for a fast lens. The diffraction of such surface relief wavelength-scale structures should be solved with rigorous electromagnetic theory. Most methods with the resonance domain diffraction theory for analysis and synthesis of diffractive optics elements are for 1-D and 2-D separable gratings, 1-D cylindrical lens and 2-D lens arrays1. Those elements are treated with the 1-D grating model. However, rigorous analysis of a single 2-D radially symmetrical diffractive lens needs solutions of the 3-D Maxwell The numerical solutions with the finite-element methods2 are usually computational expansive.
Thin-film filters with diffractive and waveguiding layers
Authors: Magnusson R. , Tibuleac S. , Liu Z. , Shin D. , Young P. P. , Wang S. S.
Published: February 2023

By merging traditional thin-film optics with diffractive and waveguide optics, it has been shown theoretically that optical reflection filters can be designed with 100% efficiency, symmetrical lineshapes, near-zero nonoscillatory sidebands over extended wavelength regions, narrow (or wide) controllable linewidths, and other favorable attributes [1]. Thus, single- and multilayer reflective filters with near ideal features have been theoretically demonstrated by utilizing anti-reflection design to suppress reflections adjacent to the resonance peak [2]. In addition, a transmission bandpass filter can be designed using guided-mode resonance effects with a highly reflecting dielectric multilayer stack [3]. This new transmission filter produces broad-range low-transmission sidebands with nearly 100% transmission efficiency at the passband. Numerous applications have been identified including laser resonator frequency-selective polarizing mirrors, laser cavity tuning elements, mirrors and phase-locking elements for vertical-cavity surface emitting laser arrays, and sensor elements [4]. Experimental results verifying the theoretically predicted high resonance efficiencies for reflection filters have been reported in the optical spectral region [5,6], in the millimeter wave region [7], and in the microwave region [8].
Optimisation of guided-mode resonance and Bragg gratings designed using rigorous diffraction theory
Authors: Layet Ben , Lightbody Malcolm T.M. , Taghizadeh Mohammad R.
Published: February 2023

We consider the implementation of several standard optical components by means of diffraction gratings. The motivation depends on the particular grating employed. A binary surface relief grating, in fused silica, for example, may provide greater robustness than, say, a multi-layer thin film. This is significant for high power laser systems. Alternatively, gratings manifesting the so-called guided-mode resonance (GMR) [1], or resonance type Wood anomaly, are of interest because ideally they give a very high performance for certain optical functions.
A Multiview Fast Optical Tomography System Using Microlens Arrays
Authors: Bishop K. P. , Pierson R. E. , Chen E. Y. , McMackin L.
Published: February 2023

In this paper, we present an application of microlens-based Hartmann wavefront sensors. The wavefront sensors, which employ arrays of one-dimensional cylindrical microlenses, are used in a multiview optical tomography system to provide a nonintrusive measurement of a dynamic heated air jet flow. A number of linear Hartmann sensors is arranged around the circumference of the region of interest (Figure 1). The tomography system uses the multiple simultaneous wavefront measurements around the circular jet to reconstruct two-dimensional estimates of the index-of-refraction variations in the flow. High speed sampling of the flow enables reconstruction of three-dimensional organized structures present in the flow.
Realization of Multilayer Diffractive Components Experimental Methods of Characterization
Authors: Giovannini H. , Akhouayri H. , Amra C.
Published: February 2023

It has been shown that multilayer coatings permit to modify the optical properties of diffraction gratings[1], which increases the fields of application of gratings, especially in micro­optics domain. For example, the efficiency of a grating for s or p polarization can be varied by depositing an optical coating on the diffracting surface[2]. Several techniques can be used to realize such components. One can mention the evaporation techniques (Electron Beam Deposition, Ion Assisted Deposition, Ion Plating) already used for thin film applications. These techniques have been used in our laboratory to realize various diffractive components. The optical properties (efficiency of diffracted orders and phase difference of the scattered field between s and p polarizations) of such components, have been measured by using two devices: one based on a goniometric ellipsometer[3], the other based on a recently developed grating interferometer[4]. The results obtained with these two techniques have been analyzed and compared to the results given by a numerical simulation based on a rigourous method, and the absorption has been measured by using a photothermal technique[5].
Experimental studies of Talbot array illuminators
Authors: Suleski Thomas J. , O’Shea Donald C.
Published: February 2023

An experimental study of Talbot array illuminators (TAIs) has been performed. These devices, first proposed and implemented by Lohmann,1 are binary phase gratings that, when properly illuminated, give rise to periodic, concentrated areas of light with uniform intensities through Fresnel diffraction. This phenomenon is generally referred to (somewhat misleadingly) as Talbot self-imaging.
Rapid Fabrication of Diffractive Micro-Lenses Using Excimer Laser Ablation
Authors: Wang Xiaomei , Leger James R. , Rediker Robert H.
Published: February 2023

Diffractive optical elements (DOEs) provide solutions for applications that require complex phase profiles which are difficult or impossible to make with conventional optics. Because of their planar nature, they have small volume and are light-weight, both of which are attractive features for many applications. Diffractive optical elements are typically fabricated by multi-mask-level photoresist patterning and sequential reactive-ion etching to form the multilevel phase profile1,2. Other fabrication techniques include direct E-beam writing, direct laser writing, single-point ablation by excimer laser3, and thin film deposition. Here we describe a new technique for rapid fabrication of diffractive optic elements and arrays using deep-UV excimer laser ablation. We have fabricated 8-level diffractive micro-lenses which have diffraction-limited focusing and near-theoretical diffraction efficiency. This technique provides a flexible means for rapid prototyping and for applications where other techniques cannot be applied or are not cost-effective.
Excimer laser micromachining for rapid fabrication of binary and blazed diffractive optical elements
Authors: Duignan Michael T. , Behrmann Gregory P.
Published: February 2023

For all their power and promise, diffractive optical elements (DOEs) are generally so difficult to fabricate and so costly to prototype that their full commercial potential has yet to be realized. Although microfabrication techniques that stem from VLSI semiconductor processes are well-developed, they usually require mass production to be economically feasible.1 Even when unit cost is not a primary consideration, the time period from design to realization of even the simplest custom DOEs can frequently run to weeks or even months. We show that we are able to produce practical diffractive elements in minutes to hours. A user has the ability to design, fabricate, gauge, and refine the diffractive structure at a single workstation. We have constructed a wide spectrum of DOEs, including spherical lenses, aspheres, toroids, as well as cylindrical and conical lenses—each in a fraction of the time required using more conventional microfabrication techniques.
Fabrication of micro-optics and diffractive lenses using analogue methods
Authors: Hutley M C
Published: February 2023

The most important aspect of producing a diffracting optical component that will compare well with its refracting or reflecting counterpart is to achieve an adequate level of diffraction efficiency. Binary diffracting structures in amplitude and phase forms have been available for about a century but since their efficiency is limited to 10% and 40% respectively they have not found significant application. In order to achieve high efficiency it is necessary to exercise some control over the form of the grooves and for most practical cases it is necessary to generate a saw-tooth “blazed” profile. A blazed profile is one in which the individual facets behave, to a first approximation, like tiny prisms which send the light by reflection or refraction in the same direction that the spacing of the grooves sends it by diffraction.
Laser Written Diffraction Gratings in Quantum Dot and Island Metal Films
Authors: Kaganovskii Yu. , Rosenbluh M.
Published: February 2023

We demonstrate a new direct method of recording of interference patterns which are stable under high light intensities. The patterns are written on thin glass films containing quantum dots or on metal island films by the interference of two pulsed laser beams. A pulsed dye laser at 584 nm, with a 7 nsec pulse, and pulse intensities of 2-5 MW/cm2 produced gratings with a period l depending on the angle, α, between the two beams according to l = λ/2sin(α/2).
High-Efficiency Transmission Gratings Fabricated in Bulk Fused Silica
Authors: Nguyen H.T. , Shore B.W. , Britten J.A. , Boyd R.D. , Bryan S.J. , Falabella S. , Perry M. D.
Published: February 2023

High power ultraviolet lasers are now widely used in the semiconductor industry and inertial confinement fusion research, and are finding increased application in medical therapy. Whether based on excimers or frequency converted solid-state, high power ultraviolet lasers continue to be plagued by issues of optical damage and a limited choice of optical components for beam manipulation. In particular, system performance is often limited by the damage threshold of cavity and transport mirrors. Beam transport and steering based on refractive optics are limited not by surface damage as is the case with reflective systems but instead by bulk damage induced by two photon absorption, color center formation and self-focusing. These limitations can, in principle, be overcome in many applications by the use of transmission gratings fabricated in high damage threshold, transparent materials.
Diffractive diffusers at the fabrication limit
Authors: Herzig Hans Peter , Singer Wolfgang , Piper Eckhard , Wangler Johannes
Published: February 2023

Diffractive micro-optical elements gained increasing interest for beam-shaping, e.g., the laser treatment of materials,1 and for illumination systems. The fabrication technologies for diffractive micro-optical elements bring in advance high accuracy and reproducibility, especially of the periodicity of the elements. In monochromatic applications, diffractive micro-optical elements are only restricted by the limits of the fabrication technology.
Design of phase–shifting masks for enhanced–resolution optical lithography
Authors: Yang Guo–Zhen , Li Zhi–Yuan , Dong Bi–Zhen , Gu Ben–Yuan , Zhang Guo–Qing
Published: February 2023

As integrated circuit (IC) technology continues to push further into the submicrometer regime, considerable effort has been devoted to finding new approaches for extending the resolution limits of optical lithographic systems. The idea of using phase–shifting masks in optical lithography is one of such resolution–enhancing techniques and is commonly attributed to Levenson.1 The problem of the design of phase–shifting mask is how to determine the phase of the mask that produces a predesignated image. There are several approaches to deal with this problem such as simulated annealing algorithm2 and optimal coherent approximations.3 In this paper we present an approach of the design of the phase–shifting mask for the enhancement of optical resolution in lithography based on general theory of amplitude–phase retrieval in optical system and an iteration algorithm. For several model objects the numerical investigating results are given.
Flattop Beam Generation Using An Iteratively-Designed Binary Phase Grating
Authors: Amako Jun , Sonehara Tomio
Published: February 2023

Various approaches for flattop beam generation have been reported.1-4) Here we focus on a grating approach in which a phase grating is used to modulate a beam wavefront and shape its Fourier spectrum. We designed a grating-type beam shaper in an iterative manner, where an optimal grating phase is sought under the constraints of amplitude and phase both in the grating and Fourier planes.
Effective medium theory of symmetric two-dimensional subwavelength periodic structures
Authors: Lalanne Philippe
Published: February 2023

Recent experimental and theoretical investigations have shown that periodic subwavelength structured surfaces with periods small compared to the illumination wavelength behave as homogeneous medium, and have suggested interesting applications, such as fabrication of anti-reflection coatings1,2,3, quarter wave plates4, polarizers5, and graded-phase diffractive elements6. The replacement of the periodic structure by a homogeneous medium is often referred as homogenization or effective medium theory (EMT). EMT can be applied to a large variety of physical material properties, such as diffusion constant, magnetic permeability, thermal conductivity, etc. To facilitate the design and fabrication of artificial dielectric elements, one must be able to relate the effective index of the subwavelength structured surface in a simple way.
Wavelength agile fluorescence microscopy filter using photorefractive barium titanate
Authors: Kersten Robert , Fernandez Salvador , Fischer George , Boyd Robert
Published: February 2023

We describe a wavelength-agile holographic notch filter (WAHNF) suitable for attenuating scattered laser light from the fluorescence signal in laser induced fluorescence (LIF) applications. The WAHNF utilizes a photorefractive material, specifically BaTiO3, and the technique of two beam coupling to attenuate the coherent portion of the signal to be detected1. Static holograms recorded in film emulsions are routinely used for this purpose but have the limitation that they are fixed notch-band devices. In contrast, the WAHNF enables tuning or switching the excitation wavelength while passively adapting to maintain the notch band centered on the laser wavelength.
Computer-generated hologram for reconstruction of unusual mode image
Authors: Wenqi Gao , Suqing Tan , Jin Zhou
Published: February 2023

Usually in reconstruction of Fourier computer-generated hologram[FCGH] the lens is necessary to make imaging at finite distance instead of imaging at infinite originally. The reconstructed images are mutual inverted ( one upright image,another inverted image) both appear in a same plane. Whether the imaging lens in reconstruction FCGH will be able to omit? Whether two reconstructed images will be able to separate in spatial? Whether two images have an identical direction and different shape in the same plane? It is the motivation for us to do this study. Through theoretic analysis and experimental reconstruction these assume can be realized essentially.
Planar integrated optics for 3-D multistage interconnection networks
Authors: Song Seok Ho , Park Suntak , Lee El-Hang
Published: February 2023

We propose a planar integrated optics for Banyan-type 3-D multistage interconnection networks. Result of planar optical experiment on signal and clock beam combination is presented.
Diffractive Elements Developed for Uniform Illumination in Inertial Confinement Fusion
Authors: Yue Qiu , Dianyuan Fan , Ximing Deng , Xuegong Deng , Yongpin Li
Published: February 2023

In inertial confinement fusion(ICF) experimental researches, especially in direct drive ICF experimental researches, energy of the incident high power laser beam must be focused onto the target surface very uniformly. To achieve high illumination uniformity for target, several techniques have been developed, such as random phase plate (PR)[1], induced spatial incoherence (ISI)[2], smoothing by spectral dispersion (SSD)[3], lenslet array (LA)[4], etc.. Although these techniques have proven valuable in ICF applications, all of them have some limitations and can't meet all of the requirements of the applications.
Achromatization for Multiple Narrowband Sources using Hybrid Multi-Order Diffractive Lenses
Authors: McIntyre Kevin J. , Morris G. Michael
Published: February 2023

Surface relief diffractive lenses that utilize multiple diffracted orders were first introduced by Sweeney and Sommargren1 and Morris and Faklis2. More comprehensive discussions of these lenses were later presented3,4,5. These multi-order diffractive (MOD) lenses were shown to have the same optical power at a discrete set of resonance wavelengths within a chosen spectral region. The physical difference between a standard diffractive lens and a MOD lens is that the OPD at the zone boundaries of a standard diffractive lens is equal to the design wavelength, whereas, for a MOD lens the OPD is equal to an integer (>1) multiple of the design wavelength. As a result, the diffraction efficiency for each order of a MOD lens has a reduced spectral bandwidth. This efficiency reduction indicates that MOD lenses may be best suited for optical systems which utilize discrete wavelength sources as opposed to broadband sources. This paper will investigate the use of MOD lenses in this class of systems by examining the combination of refractive and diffractive lens power to achieve proper achromatic control in a manner analogous to the standard hybrid lens approach. These hybrid lens combinations may be well suited for applications such as color laser printing and laser machining. Several first order design examples are provided including a two-color hybrid achromat with nearly 100% diffraction efficiency and a three-color hybrid apochromat made from a single material.
Liquid crystal grating based on modulation of circularly polarized light
Authors: Stockley Jay E. , Sharp Gary D. , Serati Steven A. , Wang Ping , Johnson Kristina M.
Published: February 2023

Liquid crystals are frequently used as active diffractive optical elements [1,2]. These materials offer several advantages, including rapid response [3], large aperture, and low cost. The simplest liquid crystal diffractive structure is a one dimensional grating comprised of a linear array of electrodes [4]. Application of different voltages along the electrode array results in a multi-level phase structure which may take the form of a blazed grating or phased array. For such devices, the phase front across the grating aperture is constructed from periodic and quantized phase steps up to 2π.
Mathematical Modeling of Diffractive Gratings
Authors: Gang Bao
Published: February 2023

Since 1990, the electromagnetic theory of gratings has received considerable attention from the applied mathematics community. Several approaches and numerical methods have been developed, including integral methods Dobson and Friedman [9], analytical continuation method Bruno and Reitich [7], and variational methods Dobson [8], Abboud [1], and Bao [3]. Significant results on existence, uniqueness, and convergence of solutions of the Maxwell have been obtained. We refer to Bao, Dobson, and Cox [5] for a survey of recent mathematical and computational results. A good introduction to the problem of electromagnetic diffraction through periodic structures can be found in Petit [12]. See also Gaylord and Moharam [10], Li [11], … for other approaches, particularly along the line of differential methods.
Applications of Guided-mode resonant filters to VCSELs
Authors: Morgan Robert A. , Cox J. Allen , Wilke Robert , Ford Carol
Published: February 2023

Within the last 2 years Vertical Cavity Surface Emitting Lasers (VCSELs) have emerged from the research laboratory into the commercial marketplace as the component of choice for numerous applications, supplanting both LED and edge-emitting sources. The enormous success of VCSELs is attributed, in part, to their premium performance, producibility, and packaging perks. Namely, significantly lower operating currents and power dissipation at Gb/s data rates; wafer-level batch fabrication, testing, and utilization of the existing LED and III-V manufacturing infrastructure; more efficient coupling into fibers and simplified drive electronics.1 These attributes result directly from the laser’s inherent vertical geometry. This vertical cavity is essentially a zero-order thin-film Fabiy-Perot transmission filter, utilizing integral quarter-wave high-reflectance (> 99%) interference stacks referred to as distributed Bragg reflectors (DBRs). On a parallel front, it has recently been suggested that high reflectivity possible from guided-mode grating resonant filters (GMGRFs)2–4 may likewise serve to construct the high-Finesse vertical cavity, requiring minimal layers. These "resonant reflectors" may be designed to provide ultra-narrow bandwidth filters for a selected center wavelength and polarization with ≅100% in-band reflectance and ~30dB sideband suppression. These are very attractive properties for VCSELs and offer the potential as an enabling tool for modal engineering.
Polarization selective diffractive optical elements and applications
Authors: Fainman Y. , Xu F. , Tyan R. , Marom D. , Shames P. , Sun P. C. , Ford J. , Scherer A. , Krishnamoorthy A.
Published: February 2023

Computer-generated holograms (CGH) fabricated as phase-only optical elements have proven to be useful for various photonic systems applications. Such elements are normally capable of implementing fixed functionality. However, the performances of packaged photonic systems will be further enhanced with availability of CGH elements with multifunctionality in polarization or color, and programmability. We have constructed polarization selective CGH which apply an independent phase profile during readout by horizontal and vertical light polarizations1–3. These elements are composed of two surface relief etched birefringent substrates joined face to face. We describe the design methodology for arbitrary birefringent substrate and gap materials. We show how these holograms are fabricated with standard microelectronics technology, and discuss the effects of etching and alignment errors on performance. We have demonstrated high diffraction efficiency with a polarization contrast ratio of over 100:1, using a multilevel phase hologram made from two birefringent lithium niobate substrates2.
Electromagnetic Analysis of Axially-Symmetric DOEs Using the FDTD Method
Authors: Prather Dennis W. , Shi Shouyuan
Published: February 2023

Many useful diffractive optical elements (DOEs) contain axial symmetry, e.g. lenses and mode shaping elements. Typically these structures are analyzed using scalar-based diffraction methods. However, when the profile of the DOE has variations on a scale comparable to the illumination wavelength scalar theory is not valid. In these cases a rigorous solution to the electromagnetic boundary value problem must be obtained. Unfortunately, most techniques for the rigorous analysis of such DOEs are only applicable to two-dimensional or periodic profiles. An exception to this is our method of moments (MOM) paper included in the technical digest of this conference. Although we have demonstrated the MOM to be a viable method for the analysis of axially-symmetric DOEs, in this paper we present an alternative technique based on the finite-difference time-domain (FDTD) method that is computationally more efficient and has broader application.
High-efficiency guided-mode resonance laser mirror
Authors: Liu Z. S. , Tibuleac S. , Shin D. , Young P. P. , Magnusson R.
Published: February 2023

Thin-film dielectric waveguides incorporating one or more periodic elements exhibit sharp variations of the externally propagating fields at certain values of the wavelength and angle of incidence that allow coupling of the incident beam to a leaky mode of the waveguide1,2. Theoretical studies indicate that with appropriate choice of materials and geometrical parameters, this guided-mode resonance (GMR) effect can be exploited to design polarized, narrowband reflection filters with efficiencies of 100%3,4. As practical applications of a filter device with such properties abound5,6, there is ample motivation for pursuing experimental proofs of these theoretically-predicted characteristics. For example, using a GMR mirror as a polarizing output coupler in a laser may require high-efficiency reflection approaching 100% with corresponding mirror transmission of a few percent yielding the laser output light7. During the past few years, experimental resonance efficiencies exceeding 90% have been reported.8–10 In this paper, a resonance filter with peak efficiency of 98% is presented and its use as output coupler in a laser cavity demonstrated.
Diffraction efficiency limitations on visually coupled hybrid optics
Authors: Tsou Brian H. , Ingling Carl R. , Beegan Julie
Published: February 2023

This is a report on the development of a psychophysical scale for measuring the image quality of photographic and video images. We found subjects can consistently use the method of direct magnitude estimation to judge the quality of images degraded by noise. An example of how this scale is used to assess the image quality produced by various optical elements will be presented.
Optical Testing of Technical Surfaces with Diffractive Optical Elements
Authors: Brinkmann Sven , Dresel Thomas , Schreiner Roland , Schwider Johannes
Published: February 2023

Optical techniques which are well established for the testing of optical surfaces usually suffer from speckle noise caused by the roughness of technical surfaces. For this reason the shape control of technical workpieces is commonly carried out by tactile profilometers. An optical and much faster alternative to mechanical profilometry is grazing incidence interferometry. It suppresses speckle noise by increasing the effective test wavelength from λ to λ/cosϑ, where ϑ is the angle of incidence [1-3]. Diffractive optical elements, containing the shape information of an ideal object in their surface relief, are used as references for the workpiece enabling a null test of the entire mantle surface in a single step. The period p of the diffractive optical elements determines the diffraction angle α=arcsin(λ/p) and hereby the angle of incidence ϑ=π-α, the effective wavelength λeff=p and the sensitivity λeff/2 of the interferometer.
Different concepts for the fabrication of hybrid (refractive/diffractive) elements
Authors: Herzig H. P. , Nussbaum Ph. , Schilling A. , Traut S. , Philipoussis I. , Ossmann C. , Völkel R. , Rossi M. , Schift H.
Published: February 2023

Various fabrication methods have been investigated to manufacture refractive and diffractive micro-optical elements [1]. The structure of the elements is generated by holographic recording, optical lithography and direct writing (e-beam, laser beam). The pattern is then transferred into quartz by reactive ion etching (RIE), or replicated into plastic for low-cost mass production. Of special interest is the fabrication of hybrid elements, which combine the unique properties of diffractive optics (fan-out, high dispersion) with those of refractive optics (high numerical aperture, low dispersion). Therefore, we have studied different concepts for the manufacturing of hybrid (refractive/diffractive) elements and we present here some first results.
Diffractive elements for the generation of propagation-invariant, rotating, and self-reproducing fields
Authors: Khonina S. N. , Kotlyar V. V. , Soifer V. A. , Pääkkönen P. , Lautanen J. , Honkanen M. , Kuittinen M. , Turunen J. , Friberg A. T.
Published: February 2023

Idealized optical fields of infinite spatial extent and energy can display a number of interesting properties, such as exact longitudinal periodicity,1 propagation-invariance,2 and rotation of the intensity distribution without any scale change.3–5 The angular spectra of all these fields consist of one or more rings, known as Montgomery’s rings.1 Therefore finite-aperture approximations can be realized by placing a filter with a set of concentric ringlike apertures (with appropriate complex-amplitude transmission functions) in the front focal plane of a collimating lens and illuminating the filter with a plane wave — this is a direct extension of the method originally proposed for the generation of propagation-invariant fields.2 However, the method outlined above suffers from poor light efficiency because only a small fraction of the incident light is transmitted by the set of ring apertures. Diffractive optics provides the means to generate propagation-invariant fields with high light efficiency using phase elements analogous to generalized axicons.6 In this paper we demonstrate experimentally that quite general rotating and self-reproducing optical fields can also be produced by means of diffractive optics.
Numerical Simulation of Binary Lenses by Direct Solution of the Helmholtz Equation
Authors: Hadley G. Ronald
Published: February 2023

Binary diffractive optics have become an important class of structures for use in optical interconnects and coupling into fibers1. Such structures have been successfully designed in the past using the techniques of Fourier analysis. These techniques are entirely adequate for near-paraxial optics such as occur with high-F-number lenses. The design of fast (F<1.5) lenses such as those required for coupling light into optical fibers, however, requires the use of more accurate techniques, most of which are based upon modal expansions2,3. In this paper we describe a new finite-difference method for modeling small-feature-size binary optical structures that involves the direct solution of the scalar Helmholtz in the vicinity of the structure, followed (in the case of lenses) by wide-angle beam propagation to predict the size of the focal spot. In this approach, the structure is described entirely by by its resulting dielectric function, allowing the treatment of aperiodic binary structures of arbitrary complexity. All reflections together with effects due to sub-wavelength feature sizes are automatically included. Polarization effects are treated approximately owing to the use of semivectorial boundary conditions at all dielectric interfaces. This technique has been shown previously4 to correctly model the behavior of first-and second-order diffraction gratings etched into waveguides. (The present method differs slightly from that described in reference 4 in that the solution method is direct matrix inversion instead of the iterative method described therein.) It involves no expansions or simplifying assumptions (aside from vectorial considerations) and is quite fast, requiring only a few minutes of workstation runtime.
Super-resolving filters as diffractive optical elements
Authors: Sheppard CJR
Published: February 2023

Super-resolving filters have potential applications in the areas of optical data storage,1-3 lithography4 and microscopy.5-6 In many applications the behaviour of the filter in the presence of defocus is important. For example, for lithography a large depth of focus is desirable, whereas in microscopy high axial resolution is often required. The effect of particular filters on the three-dimensional focal distribution has therefore been studied.7-9 It is found that filters which are super-resolving in the transverse direction can be either super-resolving or apodizing in the axial direction. Indeed, a minimum in intensity is often found along the axis at the focal point. For amplitude filters, simple design rules for the three-dimensional focusing properties have been proposed.7
Scalar-Based Design of Binary Subwavelength Diffractive Lenses
Authors: Mait Joseph N. , Prather Dennis W. , Mirotznik Mark S.
Published: February 2023

Recent research1–9 has shown that if a binary-phase diffractive optical element (DOE) has features that are on the order of the illuminating wavelength, the performance limits set by scalar-based diffraction theory can be overcome. In fact, diffraction efficiencies in excess of 90% have been predicted for binary gratings that have subwavelength features.1,4,5 Due primarily to the availability of tools for modeling, the analysis and design of subwavelength DOEs (SWDOEs) has concentrated primarily on gratings.1-7,10 To overcome this limitation, we have developed numerical routines that use a boundary element method (BEM) to analyze diffraction from finite extent, aperiodic DOEs.11 In this paper we consider diffractive design, in particular, the design of diffractive lenses, subject to the constraints of fabrication.
Three Dimensional Vector-based Analysis of Subwavelength Diffractive Optical Elements using the Finite-Difference-Time-Domain (FDTD) Method
Authors: Mirotznik Mark S. , Mait Joseph N. , Prather Dennis W. , Beck William A.
Published: February 2023

Diffractive optical elements (DOEs) whose features are smaller than the wavelength of illumination are referred to as subwavelength diffractive optical elements (SWDOEs). Subwavelength features provide SWDOEs with an added degree of flexibility over their superwavelength counterparts. For example, in the case of binary structures, SWDOEs have been shown to achieve diffraction efficiencies in excess of 90%[1]. This added flexibility, however, results in a significant cost. Namely, the analysis and subsequent design of SWDOEs require the use of rigorous electromagnetic (EM) models. These models, which incorporate the full vector nature of electromagnetic fields, can be theoretically challenging to construct and often demand considerable computational resources.
Diffractive optics for optical interconnects
Authors: Welch Hudson , Johnson Eric , Feldman Michael
Published: February 2023

Summary not available.
Locating Rotation-Invariant Optical Correlation
Authors: Zhang Yan , Gu Ben-Yuan , Dong Bi-Zhen , Yang Guo-Zhen
Published: February 2023

Optical correlation is one of important operations for many applications, for example, pattern recognition, feature extraction, and so on. With the development of optical information processing, many techniques have been applied to the optical correlation to meet different requirements. The conventional correlation is based on the Fourier transform,1,2 therefore, it is space-invariant. However, when one pays attention to the correct location of the object and does not care for whether it has been rotated at some angle. In this case, not only the space-variant but also rotation-invariant correlation is needed. In this presentation, we combine the fractional correlation with the method of the circular harmonics decomposition, and present a method to achieve the locating rotation-invariant correlation.
Character display unit using a binary phase hologram array and a LC-SLM
Authors: Kang Bong-Gyun , Kim Nam , Suh Ho-Hyung , Lee Duck-Hee
Published: February 2023

We have demonstrated the character display unit that combines the dynamic property of the LCSLM with the high efficiency property of the phase hologram fabricated by photolithography.
Binary Zone Plate Array for Parallel Joint Transform Correlator System:Design and Evaluation
Authors: Hashimoto Asako , Koda Kyoko , Kodate Kashiko , Thapliya Roshan , Kamiya Takeshi
Published: February 2023

Optical information processing systems based on Fourier transformation, such as the matched filtering correlation or the joint transform correlation, offer advantages such as parallel processing capability, direct input of signal images, freedom from electronic noise, and so on1,2). The key components of these systems are micro-optic components for generating efficient multiple image and spatial light modulators for real-time optical filtering . Binary zone plate array (BZPA), one of the diffractive optical elements, is especially attractive in the fields of optical computing and interconnection, where use of free space optics offer flexibility in designing a system of massive parallelism3,4).
Polarization analysis for detection of molecular reactions
Authors: Kley E.-B. , Schnabel B. , Riß U.
Published: February 2023

The direct measurement of molecular reactions is interesting for a lot of applications, for example for medical diagnostics, DNA, smell or taste-analysis. We have focussed on medical diagnostics. An improvement of the conventional analysis methods is possible by a direct optical measurement of the biochemical reaction. For this purpose we developed a microoptical device based on subwavelength period metal stripe gratings.
A confocal profilometer using microlens arrays
Authors: Eisner M. , Lindlein N. , Schwider J.
Published: February 2023

Confocal reflected light microscopy provides a very high depth resolution if the numerical aperture of the micro-objective is on the order of 1. The most common confocal microscopes rely on scanning the field of view by means of a Nipkow-disc or simply by mechanical scanning the object in a raster scan /l,2,3/. The basic idea of confocal imaging is spatial filtering on the way to and from the object through a small pinhole. This means that only the light from the immediate neighborhood of the image plane is allowed to pass the optical channel which means a very strong suppression of light coming from other than the plane the microscope is focused on. In a reflected light microscope the pinhole of the illuminating light path is imaged sharply onto the surface to be measured and is reflected back and has to pass the same pinhole again. Only if the pinhole is sharp on the surface to be measured the pinhole is imaged on itself and light can get through this pinhole. Unsharp imaging causes the image of the pinhole to be spread out over a considerable area which means that the total light flux is very low.
Optical Elements for Elimination of On-Axis Visible Transmission
Authors: Cai Luzhong , Li Chunfei , Zhao Jianhua , Liu Hua-Kuang
Published: February 2023

We have analyzed the transmitted spectra of optical elements including the phase gratings and Fabry-Perot (FP) and found design parameters of these elements for the elimination/reduction of on-axis transmission of broadband of visible light. In this paper, we will present a detailed theoretical analysis on the design and performance of the optical elements that will greatly reduce the transmittance of the beam in its original path of propagation. We will give the numerical computation results derived from the formula showing the spectral dependence of the direct intensity transmittance for different optical elements.
Two dimensional microoptical interconnects for a multiprocessor system
Authors: Danzer U. , Schwider J.
Published: February 2023

The trend of modern high-performance computer systems is directed towards parallel processing /1/, /2/. That results from the high complexity of physical, technical and administrative problems that must be solved. To avoid or to minimize the reduction of these multi-dimensional systems to computer compatible serial data streams, a parallel data processing is proposed. One major problem of that highly parallel multiprocessor systems is to handle the enormous data flow through the system. In that systems the data transfer and the communication protocols will be subdivided in hierarchical planes and the communication system is split into several independent interconnection networks. A common practice realizing short and medium distance bus systems is to use copper based communication media. The disadvantages of that solution are the fundamental electromagnetic properties of electrical interconnections at high frequencies. If the wavelength of the electrical signals and the transmission line have similar order of magnitude, a multitude of problems is arising. Screening of all transmission lines is necessary to prevent crosstalk through electromagnetic radiation. Termination of the lines is required to suppress reflections and standing waves and impedance matching is essential for splitting and joining signal lines.
Reactive ion etching: a versatile fabrication technique for micro-optical elements
Authors: Ferstl Margit
Published: February 2023

Reactive ion etching (RIE), a well established technology in semiconductor industries, has proven to be also a versatile tool for the fabrication of optical components. Using fluor based processes, we fabricated refractive spherical and cylindrical microlenses as well as various diffractive optical elements (DOEs) e.g. Fresnel zone lenses (FZLs), linear binary gratings, triangular gratings etc., in quartz glass and in silicon. Furthermore we realized waveguide components, above all arrayed waveguide gratings (AWGs) in silica on silicon for WDM applications. To meet the specific demands of these various optical structures (differing in shape, feature size, resolution, etch depth, etc.) appropriate structuring methods, mask materials and etching parameters had to be chosen.