bluuebunny/crossref_metadata_2025 huggingface dataset:
Waveguide gratings: new solutions for the design of filters
Authors: Lemarchand F. , Sentenac A. , Giovannini H.
Published: February 2023

Theoretical studies of reflection and transmission curves of waveguide gratings have shown that these structures permit one to realize filtering functions[1]. More recent studies have shown that some of these functions are difficult to obtain with classical multilayers[2]. For example, it is possible to realize narrowband "notch" (inverse) filters with only a modulated layer (grating) lying on a silica substrate. For such structures, the bandpass depends on the thickness of the modulated region: a smaller thickness leads to a narrower bandpass. Hence it is possible to realize narrowband (ΔZ < 1 nm) filters with very simple structures. Yet these components have shown to be highly sensitive to the angle of incidence[3]. making them difficult to use for industrial applications. To solve this problem, we have considered structures with two gratings (see Figure 1). In this case the bandpass of the filter depends on height hg, dielectric constant εg and width ag of the top grating of period 2d. The dielectric contrast of the modulated waveguide modify the dispersion of the waveguide, making (under particular conditions) the resonant structure weakly sensitive to the angle of incidence[4,5]. Theoretical calculations have shown that all the parameters can be chosen in order to increase the angular tolerance of grating waveguide filters. An improvement by a factor 10 is obtained with respect to classical grating waveguide filters (see Figure 2). Moreover, the possibility of realizing these structures by classical photolithography makes them conceivable for industrial applications. Experimental results will be given.
Inhomogeneous film deposition of SiOxNy by laser ablation
Authors: Villa F. , Soto G. , Samano E. C. , Regalado L.E. , Machorro R.
Published: February 2023

Optical interference filters are made by sequentially depositing a discrete number of layers of materials with different refractive indices. The most popular is the high-low index multilayer, essential building block for the optical industry (Ref. 1). Unfortunately, the use of discrete layers and the limited number of available refractive indices restrict the possibilities of optical performance.
Inhomogeneous thin films obtained by co-evaporation and variable aperture masks
Authors: Villa F. , Pompa O. , Regalado E. , Machorro R.
Published: February 2023

Manufacturing of inhomogeneous thin films by co-deposition of two or more materials has been known for a long time[1–3] as a promising method, however some problem with control and reproducibility of optical properties of composites and their characterization have delayed the development of a standard technique for manufacturing this kind of filters. In this work we examine the behavior of thermal sources and the control of their emission by using rotating masks of variable aperture.
CaF2-rich CaF2-TiO2 composite films prepared by reactive ion-assisted codeposition as an IR transparent coating material
Authors: Tsai Rung-Ywan , Shiau Sen-Chrong , Ho Fang Chuan
Published: February 2023

CaF2 film is the most common used low index IR coating material due to its wide transmission band (0.2-10 μm) and low water solubility. However, CaF2 thin film deposited by conventional thermal evaporation processes at an ambient temperature typically has inferior optical, structural, mechanical, and chemical properties compared with the bulk materials, which is attributed to the moisture absorption due to the columnar structure and low packing density. These problems can be remedied by energetic ion bombardments and by addition of TiO2.1,2 It has been shown that CaF2-TiO2 composite films with TiO2 contents ≧ 10 at.% prepared by reactive ion-assisted codeposition (IAD) do offer the potential of improving performance, whereas the UV and IR transmission bands decrease with increasing TiO2 contents.2 The aim of this paper is to study the optical, structural, and mechanical properties of CaF2-rich CaF2-TiO2 composite films with TiO2 contents ≦ 10 at.% prepared by reactive ion-assisted codeposition (IAD). A practical application using this composite film, which has the superior optical, structural, and mechanical properties, as a low index coating material for mid-wave IR dichroic filter is presented.
Different approaches to improve the wavefront of low-loss mirrors used in the VIRGO gravitational wave antenna
Authors: Mackowski J.M. , Pinard L. , Dognin L. , Ganau P. , Lagrange B. , Michel C. , Morgue M.
Published: February 2023

The franco-italian VIRGO program, which goal is to build a giant Michelson type interferometer (3 km arms) to detect gravitational waves, has fixed very severe optical requirements on the mirrors.
Keep-Molecules Sputtering Deposition of Magnesium Fluoride Thin Films
Authors: Kawamata K. , Shouzu T.
Published: February 2023

Magnesium fluoride thin films deposited by vacuum evaporation have been used for optical films such as anti-reflection coatings because of their low refractive index (n=1.38) and durability when condensed on heated substrates. In recent years, the demand for optical thin films by sputtering is increasing because of its advantages over vacuum evaporation in factory automation, and applicability to substrates at room temperature.
Cosputtering Some Materials in Titanium Oxides by Ion-Beam Sputtering Deposition
Authors: Hsu Jin-Cherng , Lee Cheng-Chung , Lin Jiun-Horng , King Hong-Jung , Wei David T.
Published: February 2023

Titanium dioxide is hard, environmentally stable, transparent in the range of visible and near infrared and with a very high index. In our previous papers1, we showed that the influence of oxygen partial pressure (PO2) and the optimum post-baking temperature on ion-beam sputtering deposition (IBSD) of titanium dioxide (TiCh). At high baking temperature, such as 450 °C, the amorphous-crystalline transformation cause the k values increase2 and TiO2 •3 changes easily to oxygen deficient . Some areas of the surface draw down and form mildewlike micro structure. The morphology is so irregular due to thermal instability of titanium ions. The film micro structure can be improved by co-sputtering some materials4. In this paper we extend the investigation of the co-sputtering films with various compositions.
Large Area Sputtering of Optical Thin Films in the Glass Industry
Authors: Wegener Edward J.
Published: February 2023

The last three decades in the glass industry have seen more growth and change then the last three centuries. Arguably the most significant change (excepting the adoption of the float-glass process itself) has been the advert of sputtered thin film coatings for performance and aesthetic applications.
New high-rate automated deposition system for the manufacture of complex multilayer coatings - I. System description
Authors: Sullivan Brian T. , Clarke G. , Akiyama T. , Osborne N. , Ranger M. , Dobrowolski J. A. , Howe L. , Matsumoto A. , Song Y. , Kikuchi K.
Published: February 2023

There is a need for complex thin film coatings to meet the requirements of advanced applications in different fields such as telecommunications and displays. While it has not always been possible to achieve the desired filter specifications, over the past few years recent advances in design techniques, deposition equipment and optical monitoring have allowed more complex coatings to be designed and fabricated. One example of this is a fully automated deposition system that can accurately fabricate complex coatings.1,2 This system, based on rf-magnetron sputtering, has been previously used to fabricate a wide variety of filters of varying complexities including passband filters, edge filters, broad-band antireflectance coatings, low-reflectance metal/dielectric filters and so forth. However, this system had several disadvantages including low deposition rates (< 0.1 nm/sec) and limited thickness uniformity. In this paper we will describe a new automated deposition system (ADS) that has relatively high deposition rates and a good thickness uniformity. The thickness process control will be discussed and several examples of deposited filters will be given.
Fabrication of Distributed Bragg and quarter wave reflectors for visible to mid-IR applications by reactive sputtering of silicon oxides
Authors: Simpson J , Pitt AM
Published: February 2023

The reactive sputtering of silicon in oxygen is an attractive route to producing multilayer optical coatings as a wide range of indices can be produced simply by varying oxygen feed rate. Between the two extremes of pure Si and fully oxidised SiO2 the index varies continuously with oxygen content[1] . However the optical gap also varies with composition , which can limit the applications in the visible band.
Resonant second-harmonic scattering from rough thin films
Authors: Enoch Stefan , Akhouayri Hassan , Amra C.
Published: February 2023

Recent theoretical and experimental studies of the scattering from non-linear rough metal surface have been published [1-4], Effects arising from the resonant excitation of a plasmon resonance have been investigated and peaks or dips in the angular distribution of the scattered harmonic light have been demonstrated. These peaks arise from the excitation of both a fundamental or an harmonic resonance.
Recent Advances in Solid State Electrochromic Devices at OCLI
Authors: O’Brien Nada A. , Hichwa Bryant P. , Mathew J. Gordon H. , Raksha Vladimir P. , Lahaderne Robert B.
Published: February 2023

Electrochromic devices are multilayer structures comprised of 1) an electrochromic (EC) layer such as tungsten oxide, WO3, 2) an ion storage (IS) layer or counter electrode (CE) such as nickel oxide, NiO, or iridium oxide, IrOx, 3) an ion conducting (IC) layer such as tantalum pentoxide, Ta2O5, 4) and two transparent electron conducting layers separating the EC, IS and IC layers. A transmissive all-inorganic EC device which will be the subject of this paper is shown Figure 1.
Studies on organic electroluminescent thin film devices
Authors: Liu Xu , Li Fang-hong , Gu Pei-fu , Tang Jin-fa
Published: February 2023

The progress of information technology promotes the development of new light emissive display devices. As one of great potential display techniques, organic electroluminescent (EL) thin film devices has characterized by the low driven voltage, high fluorescence quantum efficiencies, wide emitting spectrum and physical flexibility, attract much more attentions around the world in the last few years[1] [2]. Different from inorganic electroluminescent thin film device, organic EL thin film device are based on the injection effect for luminescence, that is due to the recombination of electron and holes in the diode junction region, therefore organic EL thin film device is one kind of LED device. It is important to construct an organic thin film diode structure. The currency problem is how to produce an organic LED diode of high lighting efficiency and of long working time. There are two ways to improve the device performance, one is from the material point of view, that is to say by finding out new EL materials, by the different doping methods or by the combination or a new design organic-inorganic compound to arrive the goal; the second way to realize the performance is by improving coating process, or optimization thin film diode structure. In this paper, we present our primary research works in organic EL thin film devices.
Interference Filters for Thermophotovoltaic Applications
Authors: DePoy D.M. , Dziendziel R.J. , Charache G.W. , Baldasaro P.F. , Campbell B.C.
Published: February 2023

Direct conversion of heat to electricity using Thermophotovoltaic (TPV) systems is attracting renewed attention due to recent advances on low bandgap (0.5-0.7 eV) III-V semiconductor materials and devices. TPV systems utilize the same principle of operation as solar cells. In particular, a heat source radiatively emits photons which are incident on a semiconductor TPV device. Photons with energy greater than the semiconductor bandgap, Eg (typically ranging from 0.50 eV to 0.73 eV for TPV devices), excite electrons from the valence band to the conduction band. The resultant electron-hole pairs are then collected by metal contacts and can power electrical loads. Photons with energy less than the semiconductor bandgap are parasitically absorbed as heat. In order to increase the efficiency of a TPV system, some form of spectral control is used to reflect photons with energy less than the semiconductor bandgap back to the radiator.
Spectroscopic studies of membrane protein-lipid bilayer systems deposited on multilayer thin film coatings
Authors: Salamon Zdzislaw , Tollin Gordon , Macleod Angus , Stevenson Ian C.
Published: February 2023

Although thin film coatings have been used for many years in optical investigations of biological systems (especially as narrow band light filters), more recent applications of such films in two types of spectroscopic devices, surface plasmon resonance (SPR) and optical waveguides, have provided new biophysical tools for the study of protein-protein and protein-lipid membrane interactions [1]. Although both of these techniques are based on different physical phenomena, the thin film coatings have the same function, i.e. coupling devices in which incident light, under the appropriate optical conditions, can generate an evanescent surface-bound electromagnetic field, which propagates along the interface between the thin film and the emergent dielectric medium in a manner which depends on the interface characteristics. The resulting electric field intensity is concentrated at the outer surface of the film, and diminishes exponentially on both sides of the interface. As a consequence of these properties, it is possible to use SPR and waveguide spectroscopy to probe a few nanometers from the coated surface, a distance well below the wavelength of the light used to generate the evanescent waves, and hence these phenomena have been utilized extensively in studies of surfaces and thin films [for references see 1,2]. Although numerous other optical techniques have also been applied to such systems (e.g. ellipsometry, interferometry, spectrophotometry, and various forms of microscopy), the SPR method has very recently regained its popularity, mainly because of its superior sensitivity, as well as some additional very important advantages over these other methodologies [1,2]. These latter advantages include the following. First, the complete system of measurement is located on the side of the apparatus which is remote from the sample, and thus there is no optical interference from the bulk medium. Second, the outer surface of the sample needs no treatment to increase reflectance, because the necessary high reflectivity is achieved by using total internal reflectance. Third, there are three principal parameters of the resonance that can readily be measured, thereby yielding much more information about the sample and changes within it than the simple interferometric step height used in other sensitive optical techniques.
How to determine the spectral properties of a 3-nm thin film?
Authors: Mendes Sergio B. , Burke James , Saavedra S. Scott , Li Lifeng , Peyghambarian Nasser
Published: February 2023

The optical characterization of ultra-thin films, such as molecular monolayers, is simultaneously a research tool for fundamental studies in molecule-interface interactions and an attractive configuration for a sensor platform. Molecular monolayers, which exhibit thickness of only a few nanometers, are attractive candidates for transducer layers in highly species-selective bio and chemical sensors. The planar waveguide is a configuration that has seen increasing use for research in thin film structure and surface characterization. The single mode planar waveguide, a substrate-supported dielectric layer, is an inherently sensitive geometry for probing ultra-thin films. At visible wavelengths, a single-mode planar waveguide supports up to several thousand reflections per cm of beam propagation using a ray optics model. This reflection density is about 4 orders of magnitude greater than using bulk optical elements in conventional attenuated total reflection (ATR) techniques, and yields a concomitantly much higher sensitivity. Nonetheless almost all-previous waveguide based studies have utilized monochromatic sources. Only a few works have reported spectroscopic detection either by using discrete laser lines1 or a monochromator2,3 to sequentially select a frequency to perform absorbance measurements.
Stabilization of the on-line characterization procedure using spectral monitoring data
Authors: Tikhonravov Alexander V. , Kochikov Igor V. , Trubetskov Michael K. , Krasilnikova Anna V. , Smith Douglas J.
Published: February 2023

Wideband in-situ optical monitoring enables the on-line characterization of optical coatings. Such characterization is an important part of the deposition error compensation process.1,2 In the case of bulk-like thin films and highly stable deposition processes it is possible to determine only one parameter, the current layer thickness, after the deposition of each layer.2 In the case of porous thin films and less stable deposition processes a reliable determination of optical coating parameters is more difficult, and a search for several parameters may be required after each layer deposition. A direct determination of multiple parameters from a single spectral monitoring scan may result in the instability of the determination of optical coating parameters. For this reason, a special mathematical treatment is required to provide stability of the on-line characterization procedure.
A wideband optical monitor for a planetary-rotation coating-system
Authors: Campanelli Mark B. , Smith Douglas J.
Published: February 2023

A substrate-specific, through-planet, wideband optical coating monitor is being developed to increase production yield and the understanding of physical vapor deposition (PVD) coatings fabricated in the Optical Manufacturing Laboratory at the University of Rochester’s Laboratory for Laser Energetics. In-situ wideband optical monitoring of planetary rotation systems allows direct monitoring of large, expensive substrates with complex layering schemes. The optical monitor discussed here is under development for coating several large (e.g., 80.7 x 41.7 x 9.0 cm) polarizers for the National Ignition Facility. Wideband optical monitoring of the production substrates is used in concert with an array of crystal monitors for process control, film parameter evaluation, and error detection with associated design reoptimization.
Optical and microstructural properties of silver-based films
Authors: Rafla-Yuan H. , Hichwa B. P.
Published: February 2023

Characterization of the optical and microstructural properties of durable Ag films with Variable Angle Spectroscopic Ellipsometer (VASE) and X-ray Photoelectron Spectroscopy (XPS).
Determination of the refractive index of crystalline layers, implanted materials and layers embedded in a stack, with the prism coupler
Authors: Flory F. , Tisserand S. , Massaneda J. , Pelletier E. , Lancok J. , Jelinek M.
Published: February 2023

The range of applications of optical thin films is still increasing. Then, it is necessary to have more and more performing characterization techniques. The precise knowledge of the optical properties of layers in a multilayer stack is important to make complex filters. New layer materials are also needed to make new components. So, thick crystalline layers are necessary to make micro lasers; mixtures of TiO2 and SiO2 synthesized by Ti implantation in silica allow the development of integrated optics and high efficiency gratings. It is necessary to have characterization means adapted to such particular thin films. The m-line technique has been shown to be a very sensitive and accurate method to determine the refractive index of usual materials for optical coatings[1]. We adapt this technique to answer to the need and make a study of the optical properties of the particular materials cited above.
Estimation of the optical constants and thickness of thin films using unconstrained optimization
Authors: Birgin E. G. , Martínez J. M. , Chambouleyron I.
Published: February 2023

The transmission of a thin film on a transparent substrate is a function of the wavelength (λ) and given by:1 where A, B, C, and D are functions of n(λ), k(λ), and d — the refractive index, the extinction coefficient, and the thickness of the film, respectively— and the refractive index of the substrate, assumed to be known.
Error Limits in Dispersion Analysis
Authors: Ribbing Carl G. , Malmport Andreas
Published: February 2023

There is a wide variety of methods for determination of the optical functions N(λ)=n(λ)+ik(λ) or ε(w)=ε1(ω)+iε2(ω), often named "constants", from experimental measurements.1 The methods can be split into two main categories a) One measurement over an extended wavelength range and b) two (or more) measurements at a single wavelength. The physical basis for this division is that the values of the two functions are independent at each isolated wavelength, but there is an integral relationship between the two functions over the entire wavelength range. This is exploited in methods of category a) where typically Kramers-Kronig calculations of bulk reflectance are used to calculate the phase of the complex reflectance amplitude and then N(λ) or ε(ω) are calculated from closed expressions.2 In category b-methods, no relationship between the two functions is used and then at least two measurements are needed at each wavelength.
Spectroscopic ellipsometry of slightly inhomogeneous thin films: application of the new approximation for the ellipsometric angles Ψ and Δ
Authors: Tikhonravov Alexander V. , Trubetskov Michael K. , Krasilnikova Anna V. , Masetti Enrico
Published: February 2023

Spectroscopic ellipsometry is a sensitive tool for the determination of thin film parameters and, in particular, for the investigation of thin film inhomogeneity. It was shown theoretically1,2 that the ellipsometric angle Ψ is most sensitive to the film inhomogeneity at the so-called half-wave (HW) wavelength points. The values of Ψ at the HW points can be used to determine the degree of inhomogeneity.1,2 These conclusions were obtained on the basis of the approximation that can be traced back to the early work by Schröder.3 Schroder’s approximation predicts essential properties of the ellipsometric angle Ψ but it is rather inaccurate with respect to the ellipsometric angle Δ. In particular, in this approximation the ellipsometric angle Δ is independent from the film inhomogeneity. At the same time ellipsometric experiments show that this is not true. Recently a new approximation was derived4 that allows for a more accurate study of the effects connected with the film inhomogeneity. In this paper we use this approximation to study the influence of the inhomogeneity on the ellipsometric angle Δ. The results of our theoretical study are applied to the investigation of structural properties of lanthanum fluoride films.
Modelisation of optical properties of Sn and Ge doped ln2O3
Authors: Monterrat E. , Boy Ph. , Marcel C.
Published: February 2023

Ten percent tin doped In2O3 films (ITO) and other heavily doped wide band gap oxide semiconductor films are transparent in the visible range and present a metallic behavior in the IR region. This remarkable combination of properties is very interesting for thermal applications and has been intensively studied in the past decade. Optical properties of these films are known to be strongly dependent on their electrical conductivity and are well modelized with a Drude model or a Drude-Lorentz model.[1,2,3,4]
A new type of long-wavelength cut-off filter
Authors: Dobrowolski J.A. , Li Li
Published: February 2023

There is a need in science and technology for short- and long-wavelength cut-off filters. For the visible range of wavelengths there is a very complete range of short-wavelength cut-off filters based on absorption in coloured glasses and organic dyes. Many companies provide such filters and the properties of the filters supplied by them have been summarized and compared in the past.1 Unfortunately, a corresponding set of long-wavelength cut-off filters does not exist for the visible and adjacent spectral regions. In the past, filters based on the interference of light in thin films have been used for this purpose. Such filters can be constructed with a cut-off at any desired wavelength, and almost any desired rejection can be achieved provided that a sufficiently large number of layers is used.2 The disadvantage of these devices is that, in order to achieve a rejection over a wide range of wavelengths, a number of contiguous stacks have to be used and consequently the number of layers in the resulting system can be quite large. Another disadvantage is that the range of wavelengths over which the transmittance is high can be relatively narrow, unless special designs are used, in which case the number of layers required is even larger.3
Color shift coatings produced by high rate deposition processes
Authors: Bright Clark
Published: February 2023

There has been considerable work on developing optical interference coatings that exhibit a change in color when viewed at different angles, since Dobrowolski (1) successfully demonstrated this technique for anticounterfitting. His group developed a multilayer, all-dielectric coating with a HL3HL3H design for Canadian currency. Today, many countries' currencies, valuable documents, or other important items, e.g., credit or identification cards, use optically variable devices (OVD) for security. OVD based on Fabry-Perot filters with metal reflectors and dielectric spacer layers have been demonstrated and successfully commercialized. OVD can be made as color shift films on a substrate ("foil") or deposited on a release layer or directly on a coating drum, then removed as flakes, ground into small particles and used as pigments in printing inks (2).
New developments in thin film polarizing beam-splitters
Authors: Li Li , Dobrowolski J. A.
Published: February 2023

Polarizers and polarizing beam-splitters (PBS) are important optical components and are widely used in many applications. Several parameters are often used to characterize the performance of a polarizer or a PBS. These parameters include the wavelength range or bandwidth, the angular field of the incident beam, the extinction ratio and the transmittance and reflectance for the desired polarization.
The design and manufacture of all-dielectric non-polarizing beam splitters
Authors: Ciosek J. , Dobrowolski J.A. , Clarke G. , Laframboise G.
Published: February 2023

There is a need in interferometers and other optical instruments for polarization-independent all-dielectric beam splitters. In the past, two different configurations have been used: parallel plate and cemented cube beam splitters. Commonly the angle of incidence of the light on the beam splitting surface is 45°. An ideal beam splitter would have no losses, its transmittance and reflectance would be equal over an extended spectral region and would be independent of the polarization of the incident light. The device would have a reasonable angular field. In practice, it is difficult to achieve a theoretical solution with the above stated ideal performance and even more difficult to implement it in practice.
Plasma Surface Modification and Coating of PMMA
Authors: Schulz U. , Kaiser N. , Zöller A.
Published: February 2023

Inexpensive, light weight polymers offer significant cost saving and design flexibility for optical applications. Polymethylmethacrylate (PMMA) is the most often used polymer in precision optics. It shows excellent optical properties and can easily be manufactured to form components of complicated geometry by injection molding. However, the use of plastics for optical applications is limited by physical properties of organic polymers[1,2]. The application fields for plastic optics could be expanded by coating the components. Thin anorganic films are effective to realize optical functions and to improve scratch resistance and environmental durability. Thermally induced stress caused by the different thermal expansion of organic substrate and anorganic thin films, as well as, low deposition temperatures are main problems in coating polymers. In addition, because of differing chemical behavior, each kind of polymer requires its special pre-treatment to realize sufficient adherence.
Mechanical properties of dielectric thin films
Authors: Mahodaux C. , Rigneault H. , Giovannini H. , Morreti P.
Published: February 2023

Stress in thin films deposited by Reactive Low-Voltage Ion Plating (RLVIP) and conventional reactive evaporation (RE) process is studied in air and at room temperature. Multilayers stacks are considered and the interactions layer to layer turn out to have no effect as regards to the final bending. Evolution of stress after annealing shows the possibility to reduce the stress as well as the absorption for Ta2O5 thin films. Finally, ion implantation, such as helium and xenon, at high energy, proves to be also a way to vary the stress in thin films.
In-situ stress and spectral characteristics of optical TiO2 thin films from various starting materials
Authors: Aoki Tomonori , Ogura Shigetaro
Published: February 2023

Most of optical thin films have large internal stresses. Some mechanical stability of thin film applications are under the influence of the stresses. On the other hand, these thin films have so many pores because of their columnar structures. It is well known the optical properties of the films are changed by intruding water vapor and heat cycles in vacuum and atmosphere1.
Optical and mechanical properties of thermally evaporated fluoride thin films
Authors: Zhang K. , Fahey R. , Jasinski D. , Scarpino C. , Dziendziel R. , Burger S. , DePoy D.
Published: February 2023

As a result of health and safety issues surrounding the use of radioactive materials on coated optical components, there has been renewed interest in coating materials whose optical and mechanical properties approach those offered by their radioactive counterparts. Due to the radioactive nature of ThF4 and its widespread use in optical coatings, the coating industry is examining other low index and non-radioactive fluorides as possible alternatives. In this paper, we present the results of an experimental study on the optical and mechanical properties of thermally evaporated ThF4, DyF3, CeF3, LiF, HfF4, IRX, and IRB thin films, where the materials were deposited at different substrate temperatures. The objective is to examine this series of fluorides under comparable deposition conditions and with respect to such material properties as: n and k, film stress, and environmental stability. The optical constants of these fluorides were evaluated over the wavelength region from 1.0µm to 12.5µm.
WDM filters
Authors: Duck Gary
Published: February 2023

Summary not available.
A Quantitative Study of Localized Laser Damage Morphology : Correlation with Phisical Parameters
Authors: Natoli J.Y. , Volto P. , Akhouayri H. , Albrand G. , Amra C.
Published: February 2023

Specifications on laser damage thresholds have become usual and necessary today for most optical coatings and related applications, such as American (NIF) or French (ARTHEMIS) programmes. Thanks to a support from le Centre d’Etudes Atomiques, France, our laboratory has been concerned by damage phenomena in optical coatings produced by different techniques (Electron Beam Deposition, Ion Assisted Deposition, Ion Plating) and materials (ZnS, Cryolithe, MgF2, Ta2O5, SiO2, HfO2) at LOSCM.
The correlation of laser damage threshold and optical admittance in the high power laser mirror design
Authors: Wang Ran-Hong Raymond
Published: February 2023

Different wavelength of laser mirrors ( i.e. 780nm and 1064nm) designed and coated similarly were shown to have different laser damage thresholds at Yag laser. In our case, two laser mirrors at wavelength of 780nm and 1064nm were designed and coated similarly. Laser damage test of both mirror was performed using Yag laser at 1064nm wavelength. The damage thresholds were found to be 3340 MW/cm2and 350 MW/cm2 for mirror at 1064nm and 780nm respectively. In our current study, the difference in damage threshold was correlated to the difference in final admittance of the mirror.
Theory and design of dispersive dielectric high reflectors for femtosecond pulse laser systems
Authors: Szipőcs Róbert
Published: February 2023

Nowadays, ultrashort pulse laser developing laboratories have an increasing demand for optical interference coatings, mostly for dielectric high reflectors (HR-s) with prescribed phase properties. There are two major reasons for this: on the one hand, conventional dielectric HR-s do not meet the expectations of laser developers due to the enormous bandwidth of the existing femtosecond (1 fs = 10-15 s) pulse laser systems. On the other hand, by the development and application of HR-s with special phase characteristics more compact laser systems with higher performance can be built, which can significantly lower the production costs and thus allow for mass application. Different applications call for different femtosecond pulse laser systems with individually designed thin film optics. In order to achieve the best compromise between the thin film requirements and the technological possibilities, a deep knowledge of such lasers is essential.
To the design and theory of chirped mirrors
Authors: Tikhonravov Alexander V. , Trubetskov Michael K. , Tikhonravov Andrei A.
Published: February 2023

1. Publications1,2 showed that dielectric mirrors with special phase properties, the so-called chirped mirrors, can be successfully used to design femtosecond lasers with very short pulse duration. These publications caused a considerable interest to the design and theory of chirped mirrors. The original approach1 to the design of chirped mirrors was based on the refinement of a properly chosen starting design. A starting design was a multilayer mirror with monotonically varying layer thicknesses. An alternative approach3,4 based on the transmission line theory resulted in the analytic technique for the design of chirped mirrors.
Design of broadband double-chirped mirrors for the generation of sub-10 fs laser pulses
Authors: Matuschek N. , Kärtner F. X. , Sutter D. H. , Jung I. D. , Keller U. , Scheuer V. , Tilsch M. , Tschudi T.
Published: February 2023

Rapid advances in ultrashort pulse generation resulted in sub-10 fs pulses from a Ti:sapphire laser in 1994. It became evident that the main limitation for further reduction of the pulse duration is given by the higher order dispersion in the laser. Chirped mirrors [1] provide a powerful and compact technique for dispersion compensation. Additionally, they exhibit a broader high reflectivity range in comparison to standard quarter-wave Bragg mirrors. In ref. [1], chirping means that the Bragg wavelength is gradually increased along the mirror, producing a negative group delay dispersion (ODD). However, an analytic explanation of the unwanted oscillations typically observed in the group delay and GDD of such a simple chirped mirror does not exist in standard theories of optical interference coatings. Therefore, these oscillations are very often minimized purely by computer optimization.
Design and reverse engineering of optical coatings
Authors: Tikhonravov Alexander V.
Published: February 2023

The design of optical coatings is the commonly accepted term which meaning is quite unambiguous. On the contrary the term reverse engineering is often taken variously. The meaning of this term in the following is the determination of optical parameters and thicknesses of layers of manufactured optical coatings from the spectral performance measurements.
Immersed coatings with high reflectance for TM polarization
Authors: Baumeister Philip
Published: February 2023

Consider an all-dielectric multilayer that is encapsulated in a “cemented cube.” For p linearly polarized light, the objective is to produce the maximum radiant reflectance with the minimum number of layers.
Constrained Optimization with User-Specified Functions
Authors: Goldstein Fred
Published: February 2023

Optical thin film optimization is typically based on a merit function calculated from a target list. The list includes wavelengths and corresponding transmittance, reflectance, and/or phase values. In the wider field of optimization1 we are introduced to the idea of an objective subject to constraints.
A novel design method for ultrabroadband chirped mirrors
Authors: Tempea G. , Krausz F. , Ferencz K. , Spielmann Ch.
Published: February 2023

For various applications in nonlinear optics and strong field-matter interactions pulses as short and intense as possible are required. The prerequisites of a short pulse duration are a broad spectrum and a chirp-free spectral phase (i.e. group delay dispersion, =0). Recently, very efficient methods for spectral broadening have been developed, enabling the generation of a continuum stretching from the visible to the near infrared (500-950nm). This huge spectral width corresponds to a pulse duration of less than 3fs under the assumption of a bandwidth-limited pulse (GDD=0). In order to approach this limit, the positive GDD introduced by the spectral broadening mechanism and the beam manipulation has to be compensated. For high peak powers this compensation must be introduced by reflecting optical components that provide both high reflectance and the prescribed dispersion over the broadest possible bandwidth. This is one of the challenging problems solved by the chirped mirror design algorithm we present here. The mirrors we have produced exhibit high reflectance and constant negative dispersion over the bandwidth 600-950nm (the broadest ever demonstrated, to our knowledge), and have been capable of supporting the generation pulses as short as 4fs [1].
Ultra-sensitive temperature and pressure sensor based on PDMS-based FPI and Vernier effect
Authors: Song Jiao , Sun Simei , Jiang Chao , Chen Ning , Jiang Wenbo , Liu Changning , Ren Jie , Wang Saiyu
Published: February 2023

An ultra-sensitive sensor, based on two Fabry–Perot interferometers (FPIs), has been realized for temperature and pressure sensing. A polydimethylsiloxane (PDMS)-based FPI1 was used as a sensing cavity, and a closed capillary-based FPI2 was used as a reference cavity for its insensitivity to both temperature and pressure. The two FPIs were connected in series to obtain a cascaded FPIs sensor, showing a clear spectral envelope. The temperature and pressure sensitivities of the proposed sensor reach up to 16.51 nm/°C and 100.18 nm/MPa, which are 25.4 and 21.6 times, respectively, larger than these of the PDMS-based FPI1, showing a great Vernier effect.
A Review of Optical Signal Processing
Authors: VanderLugt A.
Published: February 2023

The main topic of this conference is the application of optical techniques to numerical computation. These techniques have their roots in optical processing of images and wideband electrical signals; here we review some of the significant developments of this earlier work. The primary distinction between optical processing and computing, as I see it, is that the former generally uses integral operator algorithms as applied to analog signals whereas the latter implements algorithms applied to discrete, and often binary, data sets. The distinction is admittedly arbitrary and sometimes the same problem can be solved by either method.
Low-Energy, Fast, Thermally-Stable Optical Nor Gate in a Room-Temperature GaAs Etalon
Authors: Jewell J. L. , Lee Y. H. , Warren M. , Gibbs H. M. , Peyghambarian N.
Published: February 2023

A simple pump-and-probe technique for using a dispersively nonlinear Fabry-Perot etalon as NOR, NAND, XOR. OR and AND gates has been previously described and demonstrated using dye-filled etalons.1 We have now performed these five logic functions in a room-temperature GaAs-AlGaAs multiple-quantum-well (MQW) etalon at 82 MHz with input energies less than 3 pJ incident on the device achieving contrasts better than 5:1. Thermal stability with respect to input data was demonstrated in the NOR rate despite poor heatsinking. A similar Fabry-Perot MQW device has shown 1-ps response time.2
Transverse Effects in Optical Bistability in the Context of Parallel Processing
Authors: Firth W.J. , Moloney J.V. , Smith S.D. , Meystre P. , Wright E.M. , Mandel P. , Lugiato L.A. , Weaire D.
Published: February 2023

For reasons of speed and economy, applications of dispersive optical bistability are likely to concentrate on solid-state devices of small volume. In this paper we will discuss the modelling and optimisation of such devices, particularly in relation to possible pixel size and spatial resolution. Diffusion (1,2), rather than diffraction (3), is the dominant transverse coupling mechanism in the two current solid-state systems (InSb etalon (4) and ZnSe-spaced interference filter (5)), capable of cw hold and optical address, but we will argue that in an optimised device diffraction and diffusion will be equally important.
Distributed Computation in Neural Networks and Their Optical Analogs
Authors: Cohen Marcus
Published: February 2023

Two paths of inquiry are now converging: 1) the understanding of how parallel computation in neural networks implements pattern recognition tasks, and 2) the exploration of the broad spectrum of multiwave interactions in nonlinear crystals. Here, we will explore down the first path to the junction, just far enough to see why the computer which finally implements pattern recognition tasks in real time will be optical.
OPALS: Optical Parallel Array Logic System
Authors: Tanida J. , Ichioka Y.
Published: February 2023

A novel optical digital computing system called Optical Parallel Array Logic System (OPALS) is presented, which can execute cellular logic1 in parallel. The system is constructed on the basis of the concept of optical array logic. The pure optical version of the OPALS can be realized by using a dynamic optical coding technique and optical correlation by a multi-focus imaging system. Although the OPALS is still a conceptual system, it would be expected to be a prototype of optical digital computing systems in future.
Optical Digital Logic Operations by Two Beam Coupling in Photorefractive Material
Authors: Fainman Y. , Guest C. C. , Lee S. H.
Published: February 2023

Optical devices performing nonlinear operations are highly desirable for parallel optical computing. Nonlinear optical devices based on the liquid crystal light valve [1,2], Fabry-Perot resonator [3], acousto-optic devices [4], and, recently, on four-wave mixing in photorefractive materials [5,6] have been reported.
Digital Techniques in Optical Computing
Authors: Huang Alan
Published: February 2023

Advances in low power optical nonlinearities can be combined with the parallel noninterfering communications capability of optics to implement a new generation of digital computers.
Systolic Signal Processing with Integrated Optical Coupled-Wave Device Arrays
Authors: Nazarathy Moshe , Goodman J.W.
Published: February 2023

The data flow concept of systolic processing [1] has recently found its way into a number of optical processing architectures. [2, 3] This is not surprizing since optical processing schemes are much more closely allied with continuously flowing data than are the conventional Von Newmann processing architectures.
A Review of Spatial Light Modulators
Authors: Fisher A. D.
Published: February 2023

Over the past two decades a large variety of electronically and optically addressed devices for impressing information onto one- and two- dimensional optical wavefronts have been proposed.1−16 These spatial light modulators (SLM's) were initially developed for such applications as: 1−5projection and flat-screen display, page composers, laser printing, optical memory, incoherent-to-coherent conversion (e.g., for matched filtering and spectrum analysis), optical wavelength conversion, time-to-space conversion for optical signal processsing, and a reusable substitute for film (e.g., for Fourier-plane convolution /correlation filters, real-time holography, and synthetic aperture radar systems). Limited success in those applications has spurred proposals to employ SLM's in such more advanced contexts as: arithmetic operations (×, +, −, /) between image fields, nonlinear intensity processing (e.g., log, √, thresholding, inversion, A/D conversion), 2-D integrating detection, image-field light-level amplification and regeneration, white light/color image processing, optical feature extraction and pattern recognition (non matched-filtering approaches), edge detection, solution of partial differential equations, Boolean logic (AND, OR, NOR, XOR, etc), high-resolution adaptive optics, optical matrix algebraic computing, associative parallel processing, and optical interconnect. With continued SLM development, powerful general parallel optical computers and information processors can be seen on the horizon, probably targeted toward applications from such areas as robot vision and artificial intelligence.
Improved GaAs CCD Spatial Light Modulator Fabrication*
Authors: Burke B. E. , Nichols K. B. , Kingston R. H.
Published: February 2023

High-speed spatial light modulation using the electroabsorption effect in GaAs has been described recently (1,2). By controlling the charge level in a CCD well, the electric field, and therefore the optical absorption near the band edge, may be varied. This process suggests the possibility of electrically and optically programmable one and two-dimensional spatial light modulators operating at clock rates of as much as 1 GHz (3). One of the principle impediments to the realization of such devices is the lack of a high yield fabrication process that would make large area devices feasible. We have developed a new overlapping gate structure for Schottky barrier CCDs which has reduced photolithographic tolerances compared to current planar structures. Devices fabricated with this process have shown charge transfer inefficiencies in the low 10−4per transfer, a result which is among the best reported in GaAs.
A Microchannel Spatial Light Modulator having the function of preprocessing
Authors: Shinoda K. , Hara T. , Kato T. , Sugiyama M. , Suzuki Y.
Published: February 2023

It is necessary for image processing to preprocess the image in many cases. The microchannel spatial light modulator (MSLM) reported here has the functions of writing the positive and negative charge. Moreover it has especially the functions of zooming, deflecting and rotating images. So this device can achieve image differentiation and Laplacian operation as well as image addition, subtraction and logic operations. And it becomes easier to carry out the pattern recognition with this device.
Programmable Real-Time Incoherent Matrix Multiplier for Optical Processing
Authors: Grinberg J. , Soffer B. H. , Owechko Y. , Marom E.
Published: February 2023

Optical matrix processing systems based in part upon outer product decomposition are presented that can not only perform matrix-matrix multiplication but also many linear signal processing functions such as the calculation of the cross-ambiguity function.
Optical Matrix-Vector Multiplication Using Floating-Point Arithmetic
Authors: Bocker Richard P. , Miceli William J.
Published: February 2023

In the areas of signal, image, and information processing, more and more emphasis is being placed on parallel processing techniques for solving todays problems in real-time. Optics with its inherent parallelism has succesfully demonstrated its power in performing Fourier transforms, convolutions, and correlations. More recently, interest in performing matrix algebra optically is evident based on the proliferation of articles appearing in print in this field. However, if optical processing is to ever have a real impact on general matrix computation, then it will be necessary to generalise present, concepts to handle floating-point arithmetic as well.