Special Issue "10th Anniversary of Applied Sciences: Invited Papers in "Optics and Lasers" Section"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (20 June 2021) | Viewed by 11122

Special Issue Editors

Prof. Dr. Totaro Imasaka
E-Mail Website
Guest Editor
Professor Emeritus, Kyushu University, Fukuoka 819-0395, Japan
Interests: analytical chemistry; analytical instrumentation; analytical science; trace analysis; lasers; non-linear optics; spectrometry
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Takayoshi Kobayashi
E-Mail Website
Guest Editor
1. Professor Emeritus, The University of Tokyo, Tokyo, Japan;
2. Chair Professor, Department of Electrophysics Science, National Chiao-Tung University, Hsinchu, Taiwan;
3. Guest Professor, Center for Neuroscience and Biomedical Engineering, The University of Electro-Communications, Tokyo, Japan;
4. Tokyo University of Science, WST Center, Tokyo, Japan
Interests: ultrafast and nonlinear optical processes; quantum optics; quantum photobiology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues, 

Applied Sciences is going to reach a remarkable milestone by publishing its 10th volume, and in celebration of this special occasion, we have taken the initiative to launch a Special Issue called “10th Anniversary of Applied Sciences: Invited Papers in ‘Optics and Lasers’ Section”.

In 2014, when we received our first impact factor for Applied Sciences, we published 35 manuscripts from 53 submissions, i.e., the acceptance rate was roughly 66%. However, we have now significantly improved the review quality; hence, in 2018, we published 2703 manuscripts from 9757 submissions, keeping the acceptance rate below 28%. This reasonably gave us an impact factor jump from 1.484 in 2014 to 2.217 in 2018. We have also reduced the manuscript turnaround time; presently, the median publication time is only 37 days, which will be further reduced in the coming days, and we hope to increase the impact factor to above 3.0 by 2019.

Among all sections of Applied Sciences, ‘Optics and Lasers’ section is doing extremely well, it appears, with 1033 articles published so far, along with 272 Special Issues. On this occasion, we would like to thank our all Editorial Board Members, Managing Editors, Reviewers, and Authors for their great contributions and continuous support. Please help us to celebrate our 10th anniversary and submit your review article to the Anniversary Edition.

We would like to invite you to contribute a comprehensive review article or an original research paper, for peer-review and possible publication.

Prof. Dr. Totaro Imasaka
Prof. Dr. Takayoshi Kobayashi
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2300 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (10 papers)

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Research

Article
Optical Design of a Novel Collimator System with a Variable Virtual-Object Distance for an Inspection Instrument of Mobile Phone Camera Optics
Appl. Sci. 2021, 11(8), 3350; https://doi.org/10.3390/app11083350 - 08 Apr 2021
Cited by 4 | Viewed by 675
Abstract
The resolution performance of mobile phone camera optics was previously checked only near an infinite point. However, near-field performance is required because of reduced camera pixel sizes. Traditional optics are measured using a resolution chart located at a hyperfocal distance, which can only [...] Read more.
The resolution performance of mobile phone camera optics was previously checked only near an infinite point. However, near-field performance is required because of reduced camera pixel sizes. Traditional optics are measured using a resolution chart located at a hyperfocal distance, which can only measure the resolution at a specific distance but not at close distances. We designed a new collimator system that can change the virtual image of the resolution chart from infinity to a short distance. Hence, some lenses inside the collimator systems must be moved. Currently, if the focusing lens is moved, chromatic aberration and field curvature occur. Additional lenses are required to correct this problem. However, the added lens must not change the characteristics of the proposed collimator. Therefore, an equivalent-lens conversion method was designed to maintain the first-order and Seidel aberrations. The collimator system proposed in this study does not move or change the resolution chart. Full article
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Article
Automatic Fabric Defect Detection Method Using PRAN-Net
Appl. Sci. 2020, 10(23), 8434; https://doi.org/10.3390/app10238434 - 26 Nov 2020
Cited by 2 | Viewed by 1072
Abstract
Fabric defect detection is very important in the textile quality process. Current deep learning algorithms are not effective in detecting tiny and extreme aspect ratio fabric defects. In this paper, we proposed a strong detection method, Priori Anchor Convolutional Neural Network (PRAN-Net), for [...] Read more.
Fabric defect detection is very important in the textile quality process. Current deep learning algorithms are not effective in detecting tiny and extreme aspect ratio fabric defects. In this paper, we proposed a strong detection method, Priori Anchor Convolutional Neural Network (PRAN-Net), for fabric defect detection to improve the detection and location accuracy of fabric defects and decrease the inspection time. First, we used Feature Pyramid Network (FPN) by selected multi-scale feature maps to reserve more detailed information of tiny defects. Secondly, we proposed a trick to generate sparse priori anchors based on fabric defects ground truth boxes instead of fixed anchors to locate extreme defects more accurately and efficiently. Finally, a classification network is used to classify and refine the position of the fabric defects. The method was validated on two self-made fabric datasets. Experimental results indicate that our method significantly improved the accuracy and efficiency of detecting fabric defects and is more suitable to the automatic fabric defect detection. Full article
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Article
Process Parameter Optimization When Preparing Ti(C, N) Ceramic Coatings Using Laser Cladding Based on a Neural Network and Quantum-Behaved Particle Swarm Optimization Algorithm
Appl. Sci. 2020, 10(18), 6331; https://doi.org/10.3390/app10186331 - 11 Sep 2020
Cited by 4 | Viewed by 671
Abstract
The formation process of surface coatings fabricated with laser cladding is very complicated and coating quality is closely related to laser cladding process parameters. Generally, the optimization and control of process parameters play key roles when preparing high-quality ceramic coating. In this paper, [...] Read more.
The formation process of surface coatings fabricated with laser cladding is very complicated and coating quality is closely related to laser cladding process parameters. Generally, the optimization and control of process parameters play key roles when preparing high-quality ceramic coating. In this paper, three reasonable parameters were selected for each process parameter based on the preliminary experiment. The experiment of Ti(C, N) ceramic coating prepared with laser cladding was designed via the Taguchi method. The laser power, spot diameter, overlapping ratio, and scanning velocity were selected as the main process parameters, and their effects on coating micro-hardness were analyzed using the signal-to-noise (S/N) ratio and analysis of variance (ANOVA). Then, based on the back-propagation neural network (BPNN) and quantum-behaved particle swarm optimization (QPSO) algorithm, we created the prediction model of BPNN-QPSO neural network for laser cladding Ti(C, N) ceramic coating. The mapping of process parameters to the micro-hardness of the coating was obtained according to the model and we analyzed the influence of process parameters that interacted with the coating’s micro-hardness. The results showed that the interaction of laser cladding process parameters had a significant effect on the micro-hardness of the coating. The established BPNN-QPSO neural network model was able to map the relationship between laser cladding process parameters and coating micro-hardness. The process parameters optimized by this model had similar results with ANOVA. This research provides guidance for the selection and control of ceramic coating process parameters Ti(C, N) prepared via laser cladding. Full article
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Article
Efficient Molecular Aggregation of Rhodamine 6G and Pseudoisocyanine by Light-Induced Force
Appl. Sci. 2020, 10(10), 3563; https://doi.org/10.3390/app10103563 - 21 May 2020
Cited by 1 | Viewed by 755
Abstract
A highly efficient light-induced aggregation of porphyrin molecules in solution was recently reported for 4-[10,15,20-tris(4-sulfophenyl)-21,24-dihydroporphyrin-5-yl]benzenesulfonic acid (TPPS). Here, we demonstrate that rhodamine 6G (R6G) and pseudoisocyanine (PIC) also show efficient light-induced aggregation in unsaturated aqueous solution, being detected with a multichannel lock-in amplifier [...] Read more.
A highly efficient light-induced aggregation of porphyrin molecules in solution was recently reported for 4-[10,15,20-tris(4-sulfophenyl)-21,24-dihydroporphyrin-5-yl]benzenesulfonic acid (TPPS). Here, we demonstrate that rhodamine 6G (R6G) and pseudoisocyanine (PIC) also show efficient light-induced aggregation in unsaturated aqueous solution, being detected with a multichannel lock-in amplifier as the absorbance decrease/increase in the monomers/aggregates, induced by a laser at 633 nm, which is non-resonant off their main monomer absorption wavelengths. The light-induced aggregation states are H-aggregates that are hardly formed in the thermal equilibrium. The similar absorbance changes are absent in the monomer molecules fixed in polyvinyl alcohol (PVA) films. The aggregation efficiency defined as ( Δ A / A ) / ( U t r a p / k B T ) , where A is the absorbance of the monomers, Δ A is the absorbance increase in the aggregates, U t r a p is the optical gradient force potential, and k B T is the thermal energy at room temperature, is approximately 100 for R6G and 500 for PIC, which are much smaller than that of TPPS. Full article
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Article
Unrepeatered 240-km 64-QAM Transmission Using Distributed Raman Amplification over SMF Fiber
Appl. Sci. 2020, 10(4), 1433; https://doi.org/10.3390/app10041433 - 20 Feb 2020
Cited by 4 | Viewed by 1459
Abstract
We present a theoretical and experimental investigation of unrepeatered transmission over standard single-mode fiber (SMF-28) using several schemes of distributed Raman amplification, including first, second, and dual order. In order to further extend the transmission distance, we utilize advanced bidirectional higher-order ultra-long Raman [...] Read more.
We present a theoretical and experimental investigation of unrepeatered transmission over standard single-mode fiber (SMF-28) using several schemes of distributed Raman amplification, including first, second, and dual order. In order to further extend the transmission distance, we utilize advanced bidirectional higher-order ultra-long Raman fiber laser-based amplification, where we use fiber Bragg gratings (FBGs) to reflect Stokes-shifted light from the secondary pumps. Our work demonstrates the possibility of transmission up to 240-km span length with a total span loss of 52.7 dB. Here, we use a 28-Gbaud signal using a 64-quadrature amplitude modulation (QAM) modulation format. Our results highlight the contribution of nonlinear compensation using digital back propagation in a digital signal processor (DSP) code at the receiver. Full article
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Article
Deep Learning for Computational Mode Decomposition in Optical Fibers
Appl. Sci. 2020, 10(4), 1367; https://doi.org/10.3390/app10041367 - 18 Feb 2020
Cited by 11 | Viewed by 1642
Abstract
Multimode fibers are regarded as the key technology for the steady increase in data rates in optical communication. However, light propagation in multimode fibers is complex and can lead to distortions in the transmission of information. Therefore, strategies to control the propagation of [...] Read more.
Multimode fibers are regarded as the key technology for the steady increase in data rates in optical communication. However, light propagation in multimode fibers is complex and can lead to distortions in the transmission of information. Therefore, strategies to control the propagation of light should be developed. These strategies include the measurement of the amplitude and phase of the light field after propagation through the fiber. This is usually done with holographic approaches. In this paper, we discuss the use of a deep neural network to determine the amplitude and phase information from simple intensity-only camera images. A new type of training was developed, which is much more robust and precise than conventional training data designs. We show that the performance of the deep neural network is comparable to digital holography, but requires significantly smaller efforts. The fast characterization of multimode fibers is particularly suitable for high-performance applications like cyberphysical systems in the internet of things. Full article
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Article
Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver
Appl. Sci. 2020, 10(4), 1316; https://doi.org/10.3390/app10041316 - 15 Feb 2020
Cited by 14 | Viewed by 1199
Abstract
Arrays of nanoholes in metal are important plasmonic devices, proposed for applications spanning from biosensing to communications. In this work, we show that in such arrays the symmetry can be broken by means of the elliptical shape of the nanoholes, combined with the [...] Read more.
Arrays of nanoholes in metal are important plasmonic devices, proposed for applications spanning from biosensing to communications. In this work, we show that in such arrays the symmetry can be broken by means of the elliptical shape of the nanoholes, combined with the in-plane tilt of the ellipse axes away from the array symmetry lines. The array then differently interacts with circular polarizations of opposite handedness at normal incidence, i.e., it becomes intrinsically chiral. The measure of this difference is called circular dichroism (CD). The nanosphere lithography combined with tilted silver evaporation was employed as a low-cost fabrication technique. In this paper, we demonstrate intrinsic chirality and CD by measuring the extinction in the near-infrared range. We further employ numerical analysis to visualize the circular polarization coupling with the nanostructure. We find a good agreement between simulations and the experiment, meaning that the optimization can be used to further increase CD. Full article
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Article
An Assemble Based on Clustering and Monte Carlo for the Wavelengths Selection of Excitation Emission Fluorescence Spectra
Appl. Sci. 2020, 10(3), 1134; https://doi.org/10.3390/app10031134 - 07 Feb 2020
Viewed by 724
Abstract
Excitation-emission fluorescence spectra is very effective to predict the concentration of organics in samples. However, redundant information and noises in the excitation-emission matrix (EEM) decrease the accuracy of the prediction concentration. Here we proposed a method to select more useful excitation and emission [...] Read more.
Excitation-emission fluorescence spectra is very effective to predict the concentration of organics in samples. However, redundant information and noises in the excitation-emission matrix (EEM) decrease the accuracy of the prediction concentration. Here we proposed a method to select more useful excitation and emission spectra from the EEM to increase the accuracy of prediction concentration and reduce the processing time. First, the excitation wavelengths were selected based on the clustering method to limit the redundant information in the EEM. Then the emission wavelengths were selected based on the Monte-Carlo method. To validate this method, we established the concentration prediction model with the spectra corresponding to the selected wavelengths by partial least square regression and predicted the multi component concentrations in the test samples. Our studies indicate that incorporation of this method increases the accuracy of the prediction concentration of organics and reduces the processing time. Full article
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Article
Thermal Relaxation Spectra for Evaluating Luminescence Quantum Efficiency of CASN:Eu2+ Measured by Balanced-Detection Sagnac-Interferometer Photothermal Deflection Spectroscopy
Appl. Sci. 2020, 10(3), 1008; https://doi.org/10.3390/app10031008 - 04 Feb 2020
Cited by 2 | Viewed by 1354
Abstract
Highly sensitive broadband photothermal spectroscopy with a white-light lamp as the excitation source was developed by combining a Sagnac interferometer and balanced detection with a photothermal deflection method. A probe beam was split by a birefringent crystal CaCO3 into signal and reference [...] Read more.
Highly sensitive broadband photothermal spectroscopy with a white-light lamp as the excitation source was developed by combining a Sagnac interferometer and balanced detection with a photothermal deflection method. A probe beam was split by a birefringent crystal CaCO3 into signal and reference beams with a balanced intensity. This balanced detection enabled the measurement of photoexcited thermal relaxation spectra of materials in the air over the whole visible range in the weak excitation limit 50 µW/cm2. The photothermal excitation spectrum of Eu2+-doped CaAlSiN3 phosphors (CASN:Eu2+) with a high luminescent quantum efficiency was measured to be distinctly different from the photoluminescence excitation spectrum which reflects the absorption spectrum, revealing the thermal relaxation mechanism of the phosphor. Assuming a typical non-radiative relaxation from the higher excited states to the lowest excited state and successively to the ground state, it is demonstrated that the photoluminescence efficiency of the phosphors is readily evaluated simply by comparing the photothermal and photoluminescence excitation spectra. Full article
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Article
Tri- and Tetrahyperbolic Isofrequency Topologies Complete Classification of Bianisotropic Materials
Appl. Sci. 2020, 10(3), 763; https://doi.org/10.3390/app10030763 - 21 Jan 2020
Cited by 7 | Viewed by 901
Abstract
We describe novel topological phases of isofrequency k-space surfaces in bianisotropic optical materials—tri- and tetrahyperbolic materials—which are induced by the introduction of chirality. This completes the classification of isofrequency topologies for bianisotropic materials, as we showed that all optical materials belong to one [...] Read more.
We describe novel topological phases of isofrequency k-space surfaces in bianisotropic optical materials—tri- and tetrahyperbolic materials—which are induced by the introduction of chirality. This completes the classification of isofrequency topologies for bianisotropic materials, as we showed that all optical materials belong to one of the following topological classes—tetra-, tri-, bi-, mono-, or nonhyperbolic. We showed that phase transitions between these classes occur in the k-space directions with zero group velocity at high k-vectors. This classification is based on the sets of high-k polaritons (HKPs), supported by materials. We obtained the equation describing these sets and characterized the longitudinal polarization-impedance of HKPs. Full article
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