50,646 results match your criteria Applied optics[Journal]


Optics theory and practice in Iberoamerica: introduction to the feature issue.

Appl Opt 2020 May;59(13):IBO1-IBO5

This feature issue of Applied Optics (AO) on Optics Theory and Practice in Iberoamerica (OTPI) collects significantly expanded refereed papers presented at the multiconference RIAO-OPTILAS-MOPM, held in Cancún, Mexico, Sept. 23-27, 2019. All authors who participated at the conference were contacted and invited to contribute to this special issue. Read More

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http://dx.doi.org/10.1364/AO.396153DOI Listing

Vision measuring method for the involute profile of a gear shaft.

Appl Opt 2020 May;59(13):4183-4190

Since the involute profile error of a gear shaft influences its transmission performance, it is desirable to accurately and quickly measure its involute profiles. With the advantages of low cost, universal applicability and in situ detection, a vision measuring method for multiple involute profiles of a gear shaft is developed only using one image in this study. The base circle radius and initial position angle of the involute are obtained by geometrically fitting the involute profile. Read More

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http://dx.doi.org/10.1364/AO.388175DOI Listing

Improving thermo-optic properties of smart windows via coupling to radiative coolers: publisher's note.

Appl Opt 2020 May;59(13):4198

This publisher's note amends several equations and one formula in Appl. Opt.59, D210 (2020). Read More

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http://dx.doi.org/10.1364/AO.394626DOI Listing

Single-longitudinal-mode-operated, passively Q-switched Nd:YAG/Cr:YAG microchip laser with >100  kHz repetition rate and <400  ps pulse width.

Appl Opt 2020 May;59(13):4191-4197

We report a comprehensive design procedure for passively -switched monolithic Nd:YAG/Cr:YAG microchip lasers to realize operation conditions of the pulse repetition rate (PRR) >100kHz and pulse width (PW) <400ps, simultaneously. Crucial parameters including effective pump power and waist diameter of the pump laser, doping concentration and thickness of the Nd:YAG crystal, initial transmittance () of the Cr:YAG crystal, as well as the reflectivity of the output coupler are all considered during the design process. Two single-longitudinal-mode-operated lasers are designed and constructed according to the numerical results. Read More

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http://dx.doi.org/10.1364/AO.59.004191DOI Listing

Subaperture stitching interferometry based on the combination of the phase correlation and iterative gradient methods.

Appl Opt 2020 May;59(13):4176-4182

Subaperture stitching interferometry (SAS) is an important method for map testing of large aperture optical components, in which a mechanical structure is often employed for the testing of each subaperture. By eliminating the phase deviation of the corresponding points in the overlapping regions of every adjacent subaperture, the whole aperture map can be obtained. Accurate subaperture positioning is an important guarantee for precise stitching. Read More

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http://dx.doi.org/10.1364/AO.388515DOI Listing

Inverse design of photonic structures using an artificial bee colony algorithm.

Appl Opt 2020 May;59(13):4171-4175

We adapted the standard artificial bee colony algorithm for a binary search space in order to optimize photonic structures. The artificial bee colony algorithm in conjunction with the finite element method is applied for maximizing photonic bandgaps of photonic crystals. The proposed approach is assessed by two case studies assuming 2D photonic crystals comprised of silicon and air in a triangular lattice. Read More

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http://dx.doi.org/10.1364/AO.389475DOI Listing

Foveal scanning based on an optical-phases array.

Appl Opt 2020 May;59(13):4165-4170

We utilize the space-variant structure of the human fovea as a basis for a novel, to the best of our knowledge, foveal approach based on optical-phases array (OPA). This approach can be used to solve issues in 3D imaging and achieve a large field of view and high resolution with real-time application. A foveal scanning model based on the OPA is established. Read More

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http://dx.doi.org/10.1364/AO.383945DOI Listing

III/V silicon hybrid laser based on a resonant Bragg structure.

Appl Opt 2020 May;59(13):4158-4164

We demonstrate a laser tunable in intensity with gigahertz tuning speed based on a III/V reflective semiconductor optical amplifier (RSOA) coupled to a silicon photonic chip. The silicon chip contains a Bragg-based Fabry-Perot resonator to form a passive bandpass filter within its stopband to enable single-mode operation of the laser. We observe a side mode suppression ratio of 43 dB, linewidth of 790 kHz, and an optical output power of 1. Read More

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http://dx.doi.org/10.1364/AO.390522DOI Listing

Demonstration of wideband metal mesh filters for submillimeter astrophysics using flexible printed circuits.

Appl Opt 2020 May;59(13):4143-4150

We developed a wideband quasi-optical band-pass filter covering 170-520 GHz by exploiting the recent advancements in commercially available flexible printed circuit (FPC) fabrication technologies. We designed and fabricated a three-layered stack of loaded hexagonal grid metal meshes using a copper pattern with a narrowest linewidth of 50µ on a polyimide substrate. The measured frequency passband shape was successfully reproduced through a numerical simulation using a set of parameters consistent with the dimensions of the fabricated metal meshes. Read More

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http://dx.doi.org/10.1364/AO.389605DOI Listing

High-refractive-index capping layer improves top-light-emitting device performance.

Appl Opt 2020 May;59(13):4114-4121

The performance of top-emitting organic light-emitting devices (TEOLEDs) was improved with capping layers having high refractive indices. The TEOLED electroluminescence was examined with different capping materials on the same device structure. The luminance and power efficiency in the forward direction was improved significantly by using a high-refractive-index capping layer. Read More

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http://dx.doi.org/10.1364/AO.391419DOI Listing

Hyperspectral remote sensing image classification based on random average band selection and an ensemble kernel extreme learning machine.

Appl Opt 2020 May;59(13):4151-4157

Hyperspectral remote sensing technology can explore a lot of information about ground objects, and the information is not explored in multispectral technology. This study proposes a hyperspectral remote sensing image classification method. First, we preprocess the hyperspectral data to obtain the average spectral information of the pixels; the average spectral information contains spectral-spatial features. Read More

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http://dx.doi.org/10.1364/AO.386972DOI Listing

Micro star tracker with a curved vane for a short baffle length and sharp stray light attenuation.

Appl Opt 2020 May;59(13):4131-4142

We present a micro star tracker with curved vanes that offers a short length of the baffle and a sharp cutoff of stray light. The curved vanes are derived mathematically by ray-tracing in such a way that all the stray light from outside of the desired field of view (FOV) is reflected out. The proposed curved vane design allows a smaller number of vanes to completely cut off stray light, leading to a shorter length in baffle design. Read More

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http://dx.doi.org/10.1364/AO.380774DOI Listing

Simultaneous detection of the Ca and Ca layers by a dual-wavelength tunable lidar system.

Appl Opt 2020 May;59(13):4122-4130

A dual-wavelength tunable lidar system that simultaneously detects the Ca and layers has been established in Yanqing Station (40.41°N, 116.01°E). Read More

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http://dx.doi.org/10.1364/AO.381699DOI Listing

Mitigating weak dispersion in affordable RF-over-fiber channels.

Authors:
Er'el Granot

Appl Opt 2020 May;59(13):4105-4113

A dispersion-compensating filter for next-generation low-cost analog and digital optical links is developed. In these high-frequency optical channels, even weak dispersion can be detrimental to data encoding (e.g. Read More

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http://dx.doi.org/10.1364/AO.392619DOI Listing

Thin thermally grown oxide thickness detection in thermal barrier coatings based on SWT-BP neural network algorithm and terahertz technology.

Appl Opt 2020 May;59(13):4097-4104

Terahertz time-domain spectroscopy is a contactless and nondestructive testing technique that is often used to measure the thickness of layered materials. However, the technique presents limited thickness detection resolution, especially in the thin thermally grown oxide (TGO) of thermal barrier coatings whose thickness is below 30 µm. In this study, an SWT-BP algorithm combining a stationary wavelet transform (SWT) and a backpropagation (BP) neural network was proposed, and the regression coefficient of SWT-detailed results was 0. Read More

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http://dx.doi.org/10.1364/AO.392748DOI Listing

Application of calibration-free high repetition rate laser-ablation spark-induced breakdown spectroscopy for the quantitative elemental analysis of a silver alloy.

Appl Opt 2020 May;59(13):4091-4096

In this work, we report the application of a calibration-free (CF) method combined with high repetition rate laser-ablation spark-induced breakdown spectroscopy (HRR LA-SIBS) to the analysis of a silver alloy. The sample was ablated by a fiber laser operated at a 30 kHz pulse repetition rate, and a spark discharge was applied to enhance plasma emission. Electron number density and plasma temperature were estimated using Stark broadening of spectral lines and the Saha-Boltzmann plot method, respectively. Read More

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http://dx.doi.org/10.1364/AO.390723DOI Listing

High-performance concealment of defective pixel clusters in infrared imagers.

Appl Opt 2020 May;59(13):4081-4090

Defective pixel concealment is a necessary procedure in infrared image processing and is widely used. However, current approaches are mainly focused on the concealment of isolated pixels and small defective pixel clusters. Consequently, these approaches cannot meet the requirements when applied to infrared detectors with large defective pixel clusters. Read More

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http://dx.doi.org/10.1364/AO.391668DOI Listing

Estimation of gamma-corrected exposure time ratio in multi-exposure images for removal of moving objects.

Authors:
Seong-O Shim

Appl Opt 2020 May;59(13):4076-4080

The constructed high-dynamic-range image from merging standard low-dynamic-range images with different camera exposures contains ghost-like artifacts caused by moving objects in the scene. We present a method to utilize the gamma-corrected exposure time ratio between multi-exposure images for removal of moving objects. Between each consecutive image pair in multi-exposure images, the ratio of their exposure times is computed and raised to the power gamma, and this value is used as a cue to detect the pixels corresponding to the moving objects. Read More

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http://dx.doi.org/10.1364/AO.391150DOI Listing

Cloud scattering influence on satellite laser altimetry data and its correction.

Appl Opt 2020 May;59(13):4064-4075

Satellite laser altimetry can obtain submeter or even centimeter-level surface elevation information over a large range. However, the laser will inevitably be affected by clouds during transmission through the atmosphere, which seriously affects the accuracy of altimetry. In this paper, based on laser altimetry data, cloud optical depth inversion was realized by using the Fernald method. Read More

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http://dx.doi.org/10.1364/AO.385808DOI Listing

Propagation of positioning uncertainties in near-field goniophotometers using the Monte Carlo method.

Appl Opt 2020 May;59(13):4055-4063

The method of near-field goniophotometry is used ever-increasingly to acquire detailed luminance information about various luminaires. It overcomes certain limitations of its predecessor, the widely used and thoroughly standardized far-field goniophotometry, and provides further opportunities to expand the scope of the measurement, but also introduces a new set of limiting factors. The aim of this paper is to examine the effect of positioning uncertainties on near-field goniophotometric measurements' results. Read More

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http://dx.doi.org/10.1364/AO.386451DOI Listing

Numerical calculation of the mosaic error between mosaic gratings.

Appl Opt 2020 May;59(13):4048-4054

The theoretical calculation model for a mosaic error was established based on the plane equation for a grating surface and the relationship equation for a mosaic grating surface. A mosaic grating was obtained based on this model. In the experiment, the mosaic error was calculated based on the diffraction wavefronts of two groups of mosaic gratings that were obtained simultaneously with a Zygo interferometer. Read More

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http://dx.doi.org/10.1364/AO.389274DOI Listing

Generation and measurement of high-order optical vortices by using the cross phase.

Appl Opt 2020 May;59(13):4040-4047

We investigate a method for the generation and measurement of high-order optical vortices (OVs) by using the cross phase (CP), which is applied to implement interconversion between Laguerre-Gauss (LG) beams and Hermite-Gaussian beams in the far-field. Experimentally, we generate LG beams, which are a kind of typical OVs, with 20 radial nodes, and measure OVs with topological charges up to 200 via the CP. On this basis, we discuss the relationship between intensity distributions and the waist radius of initial light beams. Read More

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http://dx.doi.org/10.1364/AO.389617DOI Listing

Echo decomposition of full-waveform LiDAR based on a digital implicit model and a particle swarm optimization.

Appl Opt 2020 May;59(13):4030-4039

In the waveform decomposition of full-waveform LiDAR, the Gaussian model (GSM) and the generalized Gaussian model (GGSM) are widely used to extract echoes from return waveforms. However, those models have explicit functions that follow specific distribution shapes, so they are suitable only for decomposing echo waveforms with similar shapes. This paper introduces a digital implicit model (DIM) and presents a universal decomposition method for the full-waveform LiDAR. Read More

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http://dx.doi.org/10.1364/AO.390146DOI Listing

Anisotropy of acousto-optic figure of merit for the case of a Bragg-diffracted wave propagating along an optic axis in optically biaxial crystals: TlAsS crystals.

Appl Opt 2020 May;59(13):4022-4029

In the present work, we analyze acousto-optic (AO) interactions under the condition when a diffracted optical wave propagates along one of the optic axes in optically biaxial crystals. We find that the number of AO interaction types is reduced from nine, which is typical for the most general case, to six, since some of the isotropic and anisotropic diffraction types manifest themselves simultaneously. We reveal that, in the case of the interactions of quasi-ordinary and quasi-extraordinary optical waves, the dependences of effective elasto-optic coefficients and AO figure of merit on the tracing angle of an incident optical beam around the optic axis are symmetric with respect to the plane that is perpendicular to the plane of optic axes and contains the principal axis . Read More

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http://dx.doi.org/10.1364/AO.391267DOI Listing

Broadly tunable Tm/Ho-codoped fiber lasers based on temperature-sensitive single-mode-multimode-single-mode fiber structures.

Appl Opt 2020 May;59(13):4016-4021

We present all-fiber tunable lasers using single-mode-multimode-single-mode (SMS) structures involving a liquid cladding in the multimode section. We make use of large thermooptic coefficients of the refractive-index liquids to tune the laser oscillation wavelength. The oscillation wavelength is changed over a range of 100 nm from 1858 nm to 1958 nm by controlling the temperature of the SMS structures in the Tm/Ho-codoped fiber ring resonators. Read More

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http://dx.doi.org/10.1364/AO.392234DOI Listing

High-temperature stereo-digital image correlation using a single polarization camera.

Appl Opt 2020 May;59(13):4008-4015

We propose a new, to the best of our knowledge, full-frame, single-camera stereo-digital image correlation (stereo-DIC) technique that is capable of measuring surface profile and deformation over a wide temperature range. This technique uses a single polarization camera and a polarizing beam splitter to synchronously capture two full-frame sub-images with orthogonal polarization directions. By further adopting the idea of active imaging that combines monochromatic blue-light active lighting and narrow bandpass filter imaging, this system can capture stable and high-contrast speckle images of specimens at extremely high temperatures. Read More

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http://dx.doi.org/10.1364/AO.389396DOI Listing

High fidelity underwater wireless optical communication with a phase-conjugated frame structure.

Appl Opt 2020 May;59(13):4000-4007

In this paper, the influence factors of phase noise are first analyzed in detail and verified by experiments, and its principle is theoretically derived. Besides, we propose a novel, to the best of our knowledge, frame structure for m-quadrature amplitude modulation-orthogonal frequency division multiplexing (m-QAM-OFDM) in underwater wireless optical communication. The frame structure contains OFDM signals and their phase-conjugated signals. Read More

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http://dx.doi.org/10.1364/AO.388536DOI Listing

Resonator fiber-optic gyro with intensity error suppression using a bias-sampling compensation technique.

Appl Opt 2020 May;59(13):3995-3999

Resonator fiber-optic gyros (RFOGs) are one of the most promising candidates for next-generation inertial rotation sensors. The frequency servo loop is used to lock the laser frequency to the resonance frequency of fiber ring resonator via adjusting the laser diode current, which increases accompanying intensity variation and induces RFOG drift. RFOG output compensation using a bias-sampling technique is proposed to suppress intensity error. Read More

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http://dx.doi.org/10.1364/AO.389011DOI Listing

Brewster prism coupler for the intracavity excitation of TM guided modes.

Authors:
Aleksandr Shulga

Appl Opt 2020 May;59(13):3992-3994

A new type of prism coupler for intracavity excitation of TM guided modes in a planar waveguide is described. The prism coupler is made in the form of a parallelepiped with input and output faces inclined at the Brewster angle to intracavity radiation. It is shown that the prism base angle and base-to-height ratio are strongly determined by the refractive index of the prism material and the effective waveguide index of the corresponding guided mode of the waveguide structure. Read More

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http://dx.doi.org/10.1364/AO.391407DOI Listing

MAlO (M=Ba, Mg) photocatalytic activity dependence on annealing atmosphere.

Appl Opt 2020 May;59(13):D246-D252

Aluminate spinel type ${{\rm MAl}_2}{{\rm O}_4}$MAlO (M=Ba or Mg) materials prepared using the combustion synthesis method were annealed either in an air or carbon atmosphere. The materials were characterized using X-ray diffraction, scanning electron microscopy, diffuse reflectance spectra, electrochemical impedance spectroscopy, and photoluminescence (PL) measurements. Their photocatalytic activity was evaluated for the dye degradation and hydrogen evolution. Read More

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http://dx.doi.org/10.1364/AO.382912DOI Listing

Index of refraction of germanium.

Appl Opt 2020 May;59(13):3985-3991

Measurements of the index of refraction of a sample of high-quality, single-crystal germanium using the minimum deviation refractometry method are presented for temperatures near 22°C and for wavelengths in the range 2 to 14 µm. The standard uncertainty for the measurements ranges from ${1.5} \times {{10}^{ - 5}}$1. Read More

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http://dx.doi.org/10.1364/AO.382408DOI Listing

Information content of absorption spectra and implications for ocean color inversion.

Appl Opt 2020 May;59(13):3971-3984

The increasing use of hyperspectral optical data in oceanography, both in situ and via remote sensing, holds the potential to significantly advance characterization of marine ecology and biogeochemistry because, in principle, hyperspectral data can provide much more detailed inferences of ecosystem properties via inversion. Effective inferences, however, require careful consideration of the close similarity of different signals of interest, and how these interplay with measurement error and uncertainty to reduce the degrees of freedom (DoF) of hyperspectral measurements. Here we discuss complementary approaches to quantify the DoF in hyperspectral measurements in the case of in situ particulate absorption measurements, though these approaches can also be used on other such data, e. Read More

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http://dx.doi.org/10.1364/AO.389189DOI Listing

Rapid Xe-Rb spin-exchange rate measurement by using an atomic magnetometer.

Appl Opt 2020 May;59(13):3967-3970

We propose a fast and accurate method for $^ {129} {\rm Xe}{-}{\rm Rb}$Xe-Rb spin-exchange rate determination based on an atomic magnetometer at low magnetic field and low pressure. The $^ {129} {\rm Xe}{-}{\rm Rb}$Xe-Rb spin-exchange rate can be estimated via the product of the maximum transverse spin polarization of $^ {129} {\rm Xe}$Xe nuclei and the corresponding Rabi frequency. The velocity-averaged binary spin-exchange cross section and the rate constant for spin-exchange in $^ {129} {\rm Xe}{-}{\rm Rb}$Xe-Rb van der Waals complexes are measured to be ${\langle \sigma \nu \rangle _{{\rm SE}}} = ( {1. Read More

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http://dx.doi.org/10.1364/AO.390864DOI Listing

Rapid diagnosis and measurement of explosively formed projectiles based on high-quality sequential images.

Authors:
Ce Sun Yangyu Jia

Appl Opt 2020 May;59(13):3959-3966

The explosively formed projectile (EFP) is an important type of warhead technology. To verify and evaluate its design and performance, EFP testing is an essential procedure. This work applies a newly developed dual-color laser photographic system (DCLPS) to diagnose the EFP in a flight. Read More

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http://dx.doi.org/10.1364/AO.383410DOI Listing

Modified monomer diffusion model for volume holographic grating formation in photopolymers.

Appl Opt 2020 May;59(13):3952-3958

Monomer diffusion models are important in describing the formation mechanism of the volume holographic grating in photopolymers. The most representative of these models is the first-order diffusion model, which neglects the influence of the exposure intensity threshold and dissolved oxygen in a polymer. This model causes a significant deviation between the theoretical simulation and the experimental results. Read More

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http://dx.doi.org/10.1364/AO.388633DOI Listing

Atacama sub-millimeter telescope experiment polarimeter (APol) I: design and lab-test result: publisher's note.

Appl Opt 2020 May;59(13):3951

This publisher's note corrects errors in the author affiliations, abstract and the Funding sections in Appl. Opt.59, 2593 (2020). Read More

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http://dx.doi.org/10.1364/AO.395188DOI Listing

Low-stray-light concave holographic gratings processed by combining the methods of photoresist hot-melting and oxygen-ion ashing.

Appl Opt 2020 May;59(13):3942-3950

The principal motivation for this paper is to reduce stray light and line roughness in concave holographic gratings (CHG). Compared with other previously reported line-smoothing grating techniques such as dynamic-exposure near-field holography, we successfully improve the line smoothing of CHG to approximately 10 nm from 2 nm. Our method uses optimization technologies and a combination of photoresist hot-melting (PHM) and oxygen-ion ashing (OIA), thereby improving the degree of stray light before and after optimization by one order of magnitude; the level processed by OIA, PHM, and OIA successively is ${7. Read More

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http://dx.doi.org/10.1364/AO.386465DOI Listing

Fabrication of a mesoporous silica film based optical waveguide sensor for detection of small molecules.

Appl Opt 2020 May;59(13):3933-3941

In this paper, a thick mesoporous silica film (MSF) (more than 700 nm) was fabricated via the two-step enhancing Stöber solution growth approach (ESSGA). According to the optimization based on the transfer matrix method, a thicker MSF sensor has higher waveguide index sensitivity and is more suitable for the adsorbent detection, while a thinner MSF sensor has higher covered medium index sensitivity and is more appropriate for non-adsorbent detection. The covered medium index sensitivity and refractive index resolution of the fabricated MSF optical waveguide sensor were calculated to be 53. Read More

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http://dx.doi.org/10.1364/AO.389118DOI Listing

Tapered multicore fiber interferometer for refractive index sensing with graphene enhancement.

Appl Opt 2020 May;59(13):3927-3932

An in-line, highly sensitive refractive index (RI) sensor based on a tapered multicore fiber (MCF) structure sandwiched between two single-mode fibers is proposed and demonstrated. The fiber tapering technique was employed to fabricate in-line interferometers based on the multicore fiber. The waist diameter is one of the dominant factors of the intercore coupling. Read More

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http://dx.doi.org/10.1364/AO.385324DOI Listing

Robust and fast filtering method for enhancement of two-dimensional quality-guided path unwrapping algorithms.

Appl Opt 2020 May;59(13):3920-3926

This paper presents a new filtering algorithm for reducing phase noise based on the bicubic interpolation method (BIM). The unwrapped phase map accuracy is enhanced by the combination of BIM with a conventional unwrapping algorithm. The bicubic interpolation filtering (BIF) and bicubic interpolation smoothed filtering (BISF) methods are two powerful low-pass filters. Read More

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http://dx.doi.org/10.1364/AO.386064DOI Listing

Tolerancing the surface form of aspheric microlenses manufactured by wafer-level optics techniques.

Appl Opt 2020 May;59(13):3910-3919

Tolerancing is an important step toward the fabrication of high-quality and cost-effective lens surfaces. It is critical for wafer-level optics, when up to tens of thousands microlenses are fabricated in parallel and whose surfaces cannot be formed individually. However, approaches developed for macro-optics cannot be directly transposed for microlenses because of differences in fabrication and testing techniques. Read More

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http://dx.doi.org/10.1364/AO.388453DOI Listing

Theoretical approaches to study the optical response of the red-legged honeycreeper's plumage (Cyanerpes cyaneus).

Appl Opt 2020 May;59(13):3901-3909

In this paper, we investigate the unusual color effect exhibited by the plumage of the heads of Cyanerpes cyaneus males, whose color turns from green to turquoise as the angle between the illumination and observation directions is increased. This singular color effect is characteristic of species that have quasi-ordered nanostructures of short-range order within the feather barbs. However, among species of the same family and even within feather patches of the same individual, one can find barbs with different characteristics, both macroscopic (curvature, shape, cross-sectional area) and in their internal microstructure. Read More

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http://dx.doi.org/10.1364/AO.380307DOI Listing

Detection and closed-loop control of piston errors for a Fizeau imaging interferometer.

Appl Opt 2020 May;59(13):3892-3900

In the Fizeau imaging interferometer testbed we recently built, the optical path difference (OPD; i.e., piston error) among three sub-telescopes should be corrected for phased imaging to enhance the spatial resolution. Read More

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http://dx.doi.org/10.1364/AO.387895DOI Listing

THz white light cavity with nonlinear dispersion in graphene.

Appl Opt 2020 May;59(13):3886-3891

A white light cavity (WLC) scheme is proposed to achieve broadband response in the terahertz (THz) region by enhanced nonlinear dispersion in a magnetized graphene system. In the weak probe field limit, the cavity linewidth is narrowed due to electromagnetically induced transparency, and then it becomes nearly as broad as the empty-cavity linewidth under the condition of Autler-Towns splitting. It is interesting to find that the cavity linewidth can be further broadened by enhanced nonlinear dispersion. Read More

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http://dx.doi.org/10.1364/AO.389180DOI Listing

Self-localization of an uncalibrated camera through invariant properties and coded target location.

Appl Opt 2020 May;59(13):D239-D245

This paper recalls one of the most critical problems for the area of computer vision, the automatic location of a single camera. Today, several robotic devices rely on technologies other than visual information to perform self-localization. An artificial optical system will significantly benefit from knowing its location within a three-dimensional world since this is a crucial step to approach other complex tasks. Read More

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http://dx.doi.org/10.1364/AO.385841DOI Listing

Determination of 1-propanol, ethanol, and methanol concentrations in water based on a one-dimensional phoxonic crystal sensor.

Appl Opt 2020 May;59(13):3878-3885

In this research, the photonic and phononic response of one-dimensional multilayer phoxonic crystals (PxCs) with normal incident of electromagnetic and acoustic waves is discussed. The presented design can work as a highly sensitive sensor for measuring three binary alcohol/water mixtures (i.e. Read More

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http://dx.doi.org/10.1364/AO.388763DOI Listing

Single preloaded piezoelectric-ceramic-stack-actuator-based fast steering mirror with an ultrahigh natural frequency.

Appl Opt 2020 May;59(13):3871-3877

To meet the requirements of the adaptive optics systems with high bandwidths and large excursion angles, we propose a fast steering mirror (FSM) with an ultrahigh natural frequency and a large angular range. The proposed FSM is driven by a preloaded piezoelectric ceramic stack actuator (PCSA), which has a higher shear stress limit in the working direction. We describe the structure of the preloading device and analyze the stiffness improvement of the preloaded PCSA. Read More

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http://dx.doi.org/10.1364/AO.387262DOI Listing

Research on the surface morphological and electrochemical modification of polyvinyl chloride induced by KrF and ArF excimer laser direct writing.

Appl Opt 2020 May;59(13):3861-3870

To obtain superior performance in adhesion, polyvinyl chloride (PVC) substrates were modified by excimer laser direct writing with different operating wavelengths, scanning speeds, and laser fluences. The induced morphological and electrochemical changes were detailedly tested and analyzed. Microchannels were formed on the surfaces of the PVC substrates due to the laser ablation, where the melted-resolidified droplet-like structures were distributed uniformly and can significantly improve the mechanical interlock. Read More

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http://dx.doi.org/10.1364/AO.388823DOI Listing

Filter construction using Ronchi masks and Legendre polynomials to analyze the noise in aberrations by applying the irradiance transport equation.

Appl Opt 2020 May;59(13):3851-3860

We tested different optical elements placed in three different positions by applying the irradiance transport equation (ITE), obtaining the wavefront $[ W(x,y) ]$[W(x,y)] and aberration surface [$ \textit{AS}(r,\theta ) $AS(r,θ)]. The existing noise in the captures $ I $I as well as in the $ W $W and $ AS $AS were analyzed applying several filters: first a filter based on Legendre polynomials (LP), generating the most probable points increasing the data resolution; second, a filter based on a 50 deg 2D-LP was used as a multilineal fit (multiple linear regression); and third, an ideal bandpass filter in the Fourier space after inducing a periodicity using Ronchi simulated masks with periods in $ x,y,xy $x,y,xy was used to perform data scanning (similar to the four-step phase-shifting method). Signal-to-noise ratio values were obtained for each proposed filter along with the most probable image free from noise, determined from a linear combination of the original data and the applied filters. Read More

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http://dx.doi.org/10.1364/AO.389716DOI Listing

Experimental investigation on aero-optical effects of a hypersonic optical dome under different exposure times.

Appl Opt 2020 May;59(13):3842-3850

The aero-optical effects induced by the complex flow structure around a hypersonic optical dome is highly unsteady, which leads to significant differences in the imaging quality under different exposure times. It is of great significance to study the influence of exposure time on imaging quality for guiding the design of imaging guidance seekers and improving imaging guidance accuracy. Based on the hypersonic gun wind tunnel, an aero-optical effect measurement platform was built to measure the wavefront from transient exposure to long exposure. Read More

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http://dx.doi.org/10.1364/AO.387513DOI Listing