Photonics

Research

Jump to: Review

20 pages, 5606 KiB

Open AccessArticle

Fast 2D Subpixel Displacement Estimation

by Min Wan, John J. Healy and John T. Sheridan

Photonics 2024, 11(7), 625; https://doi.org/10.3390/photonics11070625 - 29 Jun 2024

Viewed by 586

Abstract

Fast and simple methods for motion estimation with subpixel accuracy are of interest in a variety of applications. In this paper, we extend a recently proposed method for quantifying 1D displacements with subpixel accuracy, referred to as the subtraction method (SM) to 2D [...] Read more.

Fast and simple methods for motion estimation with subpixel accuracy are of interest in a variety of applications. In this paper, we extend a recently proposed method for quantifying 1D displacements with subpixel accuracy, referred to as the subtraction method (SM) to 2D motion. Simulation and experimental results are presented. The results indicate that any general motion in 2D involving combinations of in-plane motions in x and y can be determined using SM after a 1D calibration. The errors between the actual motion and estimated are examined. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

17 pages, 6145 KiB

Open AccessArticle

Laser Machining at High ∼PW/cm² Intensity and High Throughput

by Nan Zheng, Ričardas Buividas, Hsin-Hui Huang, Dominyka Stonytė, Suresh Palanisamy, Tomas Katkus, Maciej Kretkowski, Paul R. Stoddart and Saulius Juodkazis

Photonics 2024, 11(7), 598; https://doi.org/10.3390/photonics11070598 - 26 Jun 2024

Cited by 1 | Viewed by 1259

Abstract

Laser machining by ultra-short (sub-ps) pulses at high intensity offers high precision, high throughput in terms of area or volume per unit time, and flexibility to adapt processing protocols to different materials on the same workpiece. Here, we consider the challenge of optimization [...] Read more.

Laser machining by ultra-short (sub-ps) pulses at high intensity offers high precision, high throughput in terms of area or volume per unit time, and flexibility to adapt processing protocols to different materials on the same workpiece. Here, we consider the challenge of optimization for high throughput: how to use the maximum available laser power and larger focal spots for larger ablation volumes by implementing a fast scan. This implies the use of high-intensity pulses approaching ∼PW/cm² at the threshold where tunneling ionization starts to contribute to overall ionization. A custom laser micromachining setup was developed and built to enable high speed, large-area processing, and easy system reconfiguration for different tasks. The main components include the laser, stages, scanners, control system, and software. Machining of metals such as Cu, Al, or stainless steel and fused silica surfaces at high fluence and high exposure doses at high scan speeds up to 3 m/s were tested for the fluence scaling of ablation volume, which was found to be linear. The largest material removal rate was 10 mm³/min for Cu and 20 mm³/min for Al at the maximum power 80 W (25 J/cm² per pulse). Modified surfaces are color-classified for their appearance, which is dependent on surface roughness and chemical modification. Such color-coding can be used as a feedback parameter for industrial process control. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

15 pages, 3284 KiB

Open AccessArticle

Monolithically Integrated Michelson Interferometer Using an InGaAs/InAlAs Quantum Cascade Laser at λ = 4 µm

by Daniel Hofstetter, Hans Beck and David P. Bour

Photonics 2024, 11(7), 593; https://doi.org/10.3390/photonics11070593 - 26 Jun 2024

Cited by 1 | Viewed by 1645 | Correction

Abstract

In the present article, we propose a monolithically integrated Michelson interferometer using a λ = 4 µm InGaAs/InAlAs quantum cascade laser as the light source. By using simple fringe detection and a four-point interpolation on each fringe, we will be able to detect [...] Read more.

In the present article, we propose a monolithically integrated Michelson interferometer using a λ = 4 µm InGaAs/InAlAs quantum cascade laser as the light source. By using simple fringe detection and a four-point interpolation on each fringe, we will be able to detect minimal object displacements of 500 nm—corresponding to 25% of half the laser emission wavelength. Such an interferometric photonic integrated circuit has interesting applications for precision computerized numerical controlled machines. Since the industrial standard of such machines currently consists of glass-based linear encoders with a resolution of 5 µm, our interferometer-based system will enable an improvement of at least one order of magnitude. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Graphical abstract

14 pages, 2637 KiB

Open AccessArticle

Analysis of Long-Distance Geometric Error Measurement and Uncertainty Based on PSD Laser Collimation Principle

by Yinbao Cheng, Penghuang Luo, Bin Shen, Yinghui Wang, Yaru Li and Shaohui Li

Photonics 2024, 11(6), 538; https://doi.org/10.3390/photonics11060538 - 4 Jun 2024

Viewed by 968

Abstract

Due to the limitations of traditional geometric error measurement, the measurement accuracy of long-stroke geometric errors is generally not high and the operation is complicated. In response to the above situation, in this study, a geometric error measurement system is built with a [...] Read more.

Due to the limitations of traditional geometric error measurement, the measurement accuracy of long-stroke geometric errors is generally not high and the operation is complicated. In response to the above situation, in this study, a geometric error measurement system is built with a laser beam as the reference line and 2D position sensitive detector as the photoelectric conversion device. The single measurement range is 40 m, and the measurement range is further expanded through the principle of segmented splicing. Using an ultra-long guide rail as the measurement object for straightness measurement, the experimental results are similar to those of a laser interferometer. The uncertainty analysis model was obtained through the analysis of quantity characteristics, and based on this, the variance synthesis theorem and probability distribution propagation principle were studied to form two uncertainty synthesis methods. The measurement evaluation results showed that the two methods were basically consistent. The work provided a reference method for the uncertainty evaluation of position-sensitive detector measurement systems in the future. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

9 pages, 2305 KiB

Open AccessCommunication

Refractive Index and Dispersion Measurement Principle with Polarization Change in Total Internal Reflection

by Jyun-Ping Chang, Cheng-Mu Tsai, Jun-Hong Weng and Pin Han

Photonics 2024, 11(6), 505; https://doi.org/10.3390/photonics11060505 - 25 May 2024

Cited by 1 | Viewed by 1274

Abstract

Refractive index measurements have been an important task for a long time because that index plays an essential role in describing the optical properties of a material. Many methods have been developed to perform that task. Some of them use interferometry to achieve [...] Read more.

Refractive index measurements have been an important task for a long time because that index plays an essential role in describing the optical properties of a material. Many methods have been developed to perform that task. Some of them use interferometry to achieve high precision. However, these configurations are complicated. Some measure the critical angle using simple structures, but their accuracy is unsatisfactory because it is difficult to judge the exact critical angle with intensity variations. Here, we propose several new schemes based on measuring the polarization change in the total internal reflection. The proposed method has the merits of simple structure and easy incident angle determination that gives the maximum phase change. Additionally, it is possible to find the material dispersion by measuring the wavelength dependence of the polarization ellipticity. Some useful formulas relating the refractive index to the maximum phase change are obtained. This work can provide valuable alternatives for refractive index measurement. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

14 pages, 3314 KiB

Open AccessArticle

Repeatable Passive Fiber Optic Coupling of Single-Mode Waveguides in High-Precision Disposable Photonic Biosensors

by Jakob Reck, Laurids von Emden, Klara Mihov, Martin Kresse, Madeleine Weigel, Tianwen Qian, Csongor Keuer, Philipp Winklhofer, Marcel Amberg, David de Felipe, Crispin Zawadzki, Moritz Kleinert, Norbert Keil and Martin Schell

Photonics 2024, 11(6), 488; https://doi.org/10.3390/photonics11060488 - 21 May 2024

Viewed by 1457

Abstract

This research demonstrates a method for the repeatable passive fiber optic coupling of single-mode waveguides with a micron-scale accuracy for high-precision disposables. The aim is to broaden the application of photonic integrated circuits (PICs) from traditional fiber optic communication systems to include medical, [...] Read more.

This research demonstrates a method for the repeatable passive fiber optic coupling of single-mode waveguides with a micron-scale accuracy for high-precision disposables. The aim is to broaden the application of photonic integrated circuits (PICs) from traditional fiber optic communication systems to include medical, life science, and environmental sensing applications. The proposed passive coupling system enables the straightforward and reliable interchange of disposable photonic chips without manual read-out unit adjustments. Robustness is attributed to the chip-side grating couplers with 3 dB coupling tolerances exceeding ± 25 µm and a mechanical three-groove kinematic method ensuring precise alignment. The system simplicity is highlighted by the simple manual insertion and fixation of silicon nitride (Si₃N₄) PICs on a carrier using magnetic force and passive alignment features. Testing on a batch of 99 identical yet independent units revealed a standard deviation (SD) of 5.1 dB in coupling loss, without realignment post-calibration. This eliminates the need for active alignment processes, showing its potential for enabling field use. A usability assessment with five untrained operators confirms the suitability for various end-users, with consistent performance in engaging and disengaging disposable PICs. The research significantly advances the integration of photonic sensor technology into practical applications, particularly for chemical and biological fluid analysis in point-of-care settings. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

11 pages, 2797 KiB

Open AccessCommunication

Sensing Characteristic Analysis of All-Dielectric Metasurfaces Based on Fano Resonance in Near-Infrared Regime

by Yongpeng Zhao, Qingfubo Geng, Jian Liu and Zhaoxin Geng

Photonics 2024, 11(5), 482; https://doi.org/10.3390/photonics11050482 - 20 May 2024

Viewed by 1084

Abstract

A novel, all-dielectric metasurface, featuring a missing wedge-shaped nanodisk, is proposed to investigate optical characteristics. By introducing symmetry-breaking to induce Fano resonance, the metasurface achieves an impressive Q-factor of 1202 in the near-infrared spectrum, with a remarkably narrow full width at half maximum [...] Read more.

A novel, all-dielectric metasurface, featuring a missing wedge-shaped nanodisk, is proposed to investigate optical characteristics. By introducing symmetry-breaking to induce Fano resonance, the metasurface achieves an impressive Q-factor of 1202 in the near-infrared spectrum, with a remarkably narrow full width at half maximum (FWHM) of less than 1 nm. The ability to adjust the wavelength resonance by manipulating the structure of the wedge-shaped nanodisk offers a simple and efficient approach for metasurface design. This breakthrough holds great potential for various applications in sensing and optical filtering, marking a significant advancement in the field of nanophotonics. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

13 pages, 4656 KiB

Open AccessArticle

Integrated Wavefront Sensing and Processing Method Utilizing Optical Neural Network

by Gang Luo, Yuanchao Geng, Deen Wang, Qiang Yuan, Dongxia Hu and Wanguo Zheng

Photonics 2024, 11(4), 351; https://doi.org/10.3390/photonics11040351 - 10 Apr 2024

Viewed by 1366

Abstract

Wavefront sensors and processors are vital components of adaptive optical (AO) systems, directly impacting the operating bandwidth. As application scenarios become increasingly complex, AO systems are confronted with more extreme atmospheric turbulence. Additionally, as optical systems scale up, the data processing demands of [...] Read more.

Wavefront sensors and processors are vital components of adaptive optical (AO) systems, directly impacting the operating bandwidth. As application scenarios become increasingly complex, AO systems are confronted with more extreme atmospheric turbulence. Additionally, as optical systems scale up, the data processing demands of AO systems increase exponentially. These challenges necessitate advancements in wavefront sensing and processing capabilities. To address this, this paper proposes an integrated wavefront sensing and processing method based on the optical neural network architecture, capable of directly providing control coefficients for the wavefront corrector. Through simulation and experimentation, this method demonstrates high sensing precision and processing speed, promising to realize large-scale, high-bandwidth AO systems. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

14 pages, 4080 KiB

Open AccessArticle

Performance Enhancement in a Few-Mode Rayleigh-Brillouin Optical Time Domain Analysis System Using Pulse Coding and LMD Algorithm

by Lixin Zhang, Xuan Li, Jianjian Wang, Lei Zhang and Yongqian Li

Photonics 2024, 11(4), 308; https://doi.org/10.3390/photonics11040308 - 27 Mar 2024

Viewed by 978

Abstract

Rayleigh Brillouin optical time domain analysis (BOTDA) uses the backscattered Rayleigh light generated in the fiber as the probe light, which has a lower detection light intensity compared to the BOTDA technique. As a result, its temperature-sensing technology suffers from a low signal-to-noise [...] Read more.

Rayleigh Brillouin optical time domain analysis (BOTDA) uses the backscattered Rayleigh light generated in the fiber as the probe light, which has a lower detection light intensity compared to the BOTDA technique. As a result, its temperature-sensing technology suffers from a low signal-to-noise ratio (SNR) and severe sensing unreliability due to the influence of the low probe signal and high noise level. The pulse coding and LMD denoising method are applied to enhance the performance of the Brillouin frequency shift detection and temperature measurement. In this study, the mechanism of Rayleigh BOTDA based on a few-mode fiber (FMF) is investigated, the principles of the Golay code and local mean decomposition (LMD) algorithm are analyzed, and the experimental setup of the Rayleigh BOTDA system using an FMF is constructed to analyze the performance of the sensing system. Compared with a single pulse of 50 ns, the 32-bit Golay coding with a pulse width of 10 ns improves the spatial resolution to 1 m. Further enhanced by the LMD algorithm, the SNR and temperature measurement accuracy are increased by 5.5 dB and 1.05 °C, respectively. Finally, a spatial resolution of 1.12 m and a temperature measurement accuracy of 2.85 °C are achieved using a two-mode fiber with a length of 1 km. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

11 pages, 5250 KiB

Open AccessArticle

Multi-Mode Long-Wavelength GaAs/AlGaAs Quantum Well Infrared Photodetectors for Circular Polarization Detection

by Jianlin Feng, Hengrui Jiang, Jun Zhao and Dayuan Xiong

Photonics 2024, 11(4), 285; https://doi.org/10.3390/photonics11040285 - 22 Mar 2024

Viewed by 1123

Abstract

We present an integrated device combining a double L-shaped chiral metasurface with long-wavelength GaAs/AlGaAs quantum well infrared photodetectors (QWIPs), achieving a circular polarized extinction ratio (CPER) as high as 45 in the long-wavelength infrared range of 7–9 μm. The unit of the chiral [...] Read more.

We present an integrated device combining a double L-shaped chiral metasurface with long-wavelength GaAs/AlGaAs quantum well infrared photodetectors (QWIPs), achieving a circular polarized extinction ratio (CPER) as high as 45 in the long-wavelength infrared range of 7–9 μm. The unit of the chiral metasurface array consists of two structurally identical L-shaped gold structures with central symmetry. The CPER of the double L-shaped QWIPs is 14 times higher than that of a single L-shaped QWIP. The device operates in three modes within the detection band: the microcavity mode, the surface plasmon polariton (SPP) mode, and the hybrid mode. The double L-shaped chiral structure selects and reflects a small portion of left-handed circularly polarized light (LCP), while the majority enters the device and excites SPP modes with the bottom gold grating layer, leading to an absorption enhancement. In contrast, right-handed circularly polarized light (RCP) is mostly reflected with limited excitation of SPP waves. QWIPs exhibit a peak absorption of 0.8 and a coupling efficiency of 2700% in the active region of the quantum well due to the combined effects of the microcavity and SPP modes, in which the SPP mode plays a dominant role. The proposed device maintains high circular polarization discrimination capability under large incident angles and can be applied in spectral imaging. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

14 pages, 2478 KiB

Open AccessArticle

Classifying Raman Spectra of Colon Cells Based on Machine Learning Algorithms

by Maria Lasalvia, Crescenzio Gallo, Vito Capozzi and Giuseppe Perna

Photonics 2024, 11(3), 275; https://doi.org/10.3390/photonics11030275 - 21 Mar 2024

Viewed by 1350

Abstract

Colorectal cancer is very widespread in developed countries. Its diagnosis partly depends on pathologists’ experience and their laboratories’ instrumentation, producing uncertainty in diagnosis. The use of spectroscopic techniques sensitive to the cellular biochemical environment could aid in achieving a reliable diagnosis. So, we [...] Read more.

Colorectal cancer is very widespread in developed countries. Its diagnosis partly depends on pathologists’ experience and their laboratories’ instrumentation, producing uncertainty in diagnosis. The use of spectroscopic techniques sensitive to the cellular biochemical environment could aid in achieving a reliable diagnosis. So, we used Raman micro-spectroscopy, combined with a spectral analysis by means of machine learning methods, to build classification models, which allow colon cancer to be diagnosed in cell samples, in order to support such methods as complementary tools for achieving a reliable identification of colon cancer. The Raman spectra were analyzed in the 980–1800 cm⁻¹ range by focusing the laser beam onto the nuclei and the cytoplasm regions of single FHC and CaCo-2 cells (modelling healthy and cancerous samples, respectively) grown onto glass coverslips. The comparison of the Raman intensity of several spectral peaks and the Principal Component Analysis highlighted small biochemical differences between healthy and cancerous cells mainly due to the larger relative lipid content in the former cells with respect to the latter ones and to the larger relative amount of nucleic acid components in cancerous cells compared with healthy ones. We considered four classification algorithms (logistic regression, support vector machine, k nearest neighbors, and a neural network) to associate unknown Raman spectra with the cell type to which they belong. The built machine learning methods achieved median values of classification accuracy ranging from 95.5% to 97.1%, sensitivity values ranging from 95.5% to 100%, and specificity values ranging from 93.9% to 97.1%. The same median values of the classification parameters, which were estimated for a testing set including unknown spectra, ranged between 93.1% and 100% for accuracy and between 92.9% and 100% for sensitivity and specificity. A comparison of the four methods pointed out that k nearest neighbors and neural networks better perform the classification of nucleus and cytoplasm spectra, respectively. These findings are a further step towards the perspective of clinical translation of the Raman technique assisted by multivariate analysis as a support method to the standard cytological and immunohistochemical methods for diagnostic purposes. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

13 pages, 939 KiB

Open AccessArticle

Fluorescence-Based Aqueous Phosphate Sensing Using Eu(cpboda)(DMF)₂

by Benjamin R. Anderson, Natalie Gese, Pranav Nawani and Hergen Eilers

Photonics 2024, 11(3), 250; https://doi.org/10.3390/photonics11030250 - 11 Mar 2024

Viewed by 1141

Abstract

Fluorescence-based phosphate sensing using phosphate-sensitive phosphors is a promising approach for in situ monitoring of phosphate pollution in waterways and reservoirs. To date, the most sensitive phosphor developed for this purpose is Tb(cpboda)(DMF)₂, where cpboda = (3,3^′-((5-Carboxy-1,3-phenylene)bis(oxy))dibenzoic acid). In [...] Read more.

Fluorescence-based phosphate sensing using phosphate-sensitive phosphors is a promising approach for in situ monitoring of phosphate pollution in waterways and reservoirs. To date, the most sensitive phosphor developed for this purpose is Tb(cpboda)(DMF)₂, where cpboda = (3,3^′-((5-Carboxy-1,3-phenylene)bis(oxy))dibenzoic acid). In this study, we further improve this sensitivity by replacing the

{Tb}^{3 +}

ions with

{Eu}^{3 +}

ions to make Eu(cpboda)(DMF

)_{2}

and find concentration-independent phosphate-sensitivity of 1570 ± 120, which is

\approx 8 \times

more sensitive than the Tb-version. This improvement is attributed to

{Eu}^{3 +}

having a hypersensitive transition, while

{Tb}^{3 +}

does not. Additionally, we characterize the phosphor’s optical properties, photodegradation, and water solubility. We find that the phosphor presents challenges with regards to both photodegradation and solubility, as it is found to be poorly soluble in water and is quickly photodegraded under UV radiation

< 360

nm. However, these obstacles can, in theory, be overcome with the use of direct excitation of the

{Eu}^{3 +}

ions at 394 nm and careful design of an analysis instrument to reduce concentration variations. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

9 pages, 4569 KiB

Open AccessCommunication

Response Time of III-V Multistage Detectors Based on the “Ga-Free” InAs/InAsSb Type-II Superlattice

by Karol Dąbrowski, Waldemar Gawron and Piotr Martyniuk

Photonics 2024, 11(3), 224; https://doi.org/10.3390/photonics11030224 - 29 Feb 2024

Cited by 3 | Viewed by 1271

Abstract

This paper presents a response time/time constant of III-V material-based interband long wavelength multistage infrared detector optimized for a wavelength of 10.6 µm at 200 K. The device is based on the InAs/InAsSb type-II superlattice with highly doped p⁺/n⁺ tunneling [...] Read more.

This paper presents a response time/time constant of III-V material-based interband long wavelength multistage infrared detector optimized for a wavelength of 10.6 µm at 200 K. The device is based on the InAs/InAsSb type-II superlattice with highly doped p⁺/n⁺ tunneling junctions among the stages. The detector exhibits a response time of 9.87 ns under zero voltage condition, while for 0.15 V reverse bias, that time decreases to approximately 350 ps. The presented device shows a significant increase in response time, especially for low bias, and for a voltage of −0.2 V, the decrease in the detector’s response time by an order of magnitude was estimated. Higher voltage slightly affects the time constant, and between −0.3 V and −1 V, it varies between 300 and 400 ps. The significant change in the detector’s response time between −0.1 V and −0.2 V probably results from electric field drop over entire absorber region. The optimal operating condition can be reached for −0.15 V, where the time constant reaches approximately 350 ns with peak detectivity at a level of ~3 × 10⁹ Jones. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

14 pages, 5703 KiB

Open AccessArticle

The Design of a Photonic Crystal Fiber for Hydrogen Cyanide Gas Detection

by Abdolreza Pourfathi Fard, Somayeh Makouei, Morad Danishvar and Sebelan Danishvar

Photonics 2024, 11(2), 178; https://doi.org/10.3390/photonics11020178 - 16 Feb 2024

Viewed by 1391

Abstract

Hydrogen cyanide gas is a dangerous and fatal gas that is one of the causes of air pollution in the environment. A small percentage of this gas causes poisoning and eventually death. In this paper, a new PCF is designed that offers high [...] Read more.

Hydrogen cyanide gas is a dangerous and fatal gas that is one of the causes of air pollution in the environment. A small percentage of this gas causes poisoning and eventually death. In this paper, a new PCF is designed that offers high sensitivity and low confinement loss in the absorption wavelength of hydrogen cyanide gas. The proposed structure consists of circular layers that are located around the core, which is also composed of circular microstructures. The finite element method (FEM) is used to simulate the results. According to the results, the PCF gives a high relative sensitivity of 65.13% and a low confinement loss of 1.5 × 10⁻³ dB/m at a wavelength of 1.533 µm. The impact of increasing the concentration of hydrogen cyanide gas on the relative sensitivity and confinement loss is investigated. The high sensitivity and low confinement losses of the designed PCF show that this optical structure could be a good candidate for the detection of this gas in industrial and medical environments. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

14 pages, 12997 KiB

Open AccessArticle

Harnessing Multistability: A Novel Approach to Optical Logic Gate Construction Using Erbium-Doped Fiber Lasers

by Safara Bibi, Guillermo Huerta-Cuellar, José Luís Echenausía-Monroy, Rider Jaimes-Reátegui, Juan Hugo García-López and Alexander N. Pisarchik

Photonics 2024, 11(2), 176; https://doi.org/10.3390/photonics11020176 - 15 Feb 2024

Cited by 1 | Viewed by 1145

Abstract

We present an innovative method harnessing multistability within a diode-pumped erbium-doped fiber laser to construct logic gates. Our approach involves manipulating the intensity of external noise to regulate the probability of transitioning among four concurrent attractors. In this manner, we facilitate the realization [...] Read more.

We present an innovative method harnessing multistability within a diode-pumped erbium-doped fiber laser to construct logic gates. Our approach involves manipulating the intensity of external noise to regulate the probability of transitioning among four concurrent attractors. In this manner, we facilitate the realization of OR, AND, NOR, and NAND logic operations, aligning with the coexisting period-1, period-3, period-4, and period-5 orbits. Employing detrended fluctuation analysis, we establish equilibrium in the probability distributions of these states. The obtained results denote a substantial advancement in the field of optical logic gate development, representing a pivotal stride toward the seamless integration of an all-optical logic gate within laser oscillator-based systems. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

13 pages, 3218 KiB

Open AccessArticle

Enhanced THz Circular-Polarization Detection in Miniaturized Chips with Chiral Antennas

by Fangzhe Li, Jing Zhou, Jie Deng, Jinyong Shen, Tianyun Zhu, Wenji Jing, Xu Dai, Jiexian Ye, Yujie Zhang, Junwei Huang and Xiaoshuang Chen

Photonics 2024, 11(2), 162; https://doi.org/10.3390/photonics11020162 - 7 Feb 2024

Viewed by 1675

Abstract

Recent advancements in terahertz (THz) wave technology have highlighted the criticality of circular-polarization detection, fostering the development of more compact, efficient on-chip THz circular-polarization detectors. In response to this technological imperative, we presented a chiral-antenna-integrated GaAs/AlGaAs quantum well (QW) THz detector. The chiral [...] Read more.

Recent advancements in terahertz (THz) wave technology have highlighted the criticality of circular-polarization detection, fostering the development of more compact, efficient on-chip THz circular-polarization detectors. In response to this technological imperative, we presented a chiral-antenna-integrated GaAs/AlGaAs quantum well (QW) THz detector. The chiral antenna selectively couples the incident light of a specific circular-polarization state into a surface-plasmon polariton wave that enhances the absorptance of the QWs by a factor of 12 relative to a standard 45° faceted device, and reflects a significant amount of the incident light of the orthogonal circular-polarization state. The circular-polarization selectivity is further enhanced by the QWs with a strong intrinsic anisotropy, resulting in a circular-polarization extinction ratio (CPER) as high as 26 at 6.52 THz. In addition, the operation band of the device can be adjusted by tuning the structural parameters of the chiral structure. Moreover, the device preserves a high performance for oblique incidence within a range of ±5°, and the device architecture is compatible with a focal plane array. This report communicates a promising approach for the development of miniaturized on-chip THz circular-polarization detectors. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

12 pages, 3149 KiB

Open AccessArticle

Small Footprint and High Extinction Ratio Cladding-Modulated Bragg Grating Structure as a Wideband Bandstop Filter

by Muhammad A. Butt and Ryszard Piramidowicz

Photonics 2024, 11(2), 158; https://doi.org/10.3390/photonics11020158 - 6 Feb 2024

Cited by 1 | Viewed by 1159

Abstract

This study presents a comprehensive numerical investigation of silicon Bragg grating (BG) waveguide structures with cladding modulation. The device design features a uniform silicon ridge waveguide with corrugated cladding on both sides. Two distinct architectures are explored: one where silicon serves as the [...] Read more.

This study presents a comprehensive numerical investigation of silicon Bragg grating (BG) waveguide structures with cladding modulation. The device design features a uniform silicon ridge waveguide with corrugated cladding on both sides. Two distinct architectures are explored: one where silicon serves as the cladding and another where gold (Au) is employed. Our detailed analysis uncovers compelling results for both configurations. The silicon corrugated cladding BG waveguide demonstrates a bandstop bandwidth of ~50 nm, accompanied by an extinction ratio (ER) of 7.98 dB. The device footprint is compact, measuring approximately 16.4 × 3 µm². In contrast, the Au corrugated cladding BG waveguide exhibits exceptional performance, boasting a wideband bandstop bandwidth of ~143 nm and an impressive ER of 19.96 dB. Despite this enhanced functionality, the device maintains a reasonably small footprint at around 16.9 × 3 µm². This investigation underscores the potential of Au corrugated cladding BG waveguides as ideal candidates for achieving high-spectral-characteristic bandstop filters. The significant improvement in bandstop bandwidth and ER makes them promising for advanced optical filtering applications. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

15 pages, 4729 KiB

Open AccessArticle

Comparison between Different Optical Configurations of Active-FRAME Setup in Multispectral Imaging of Flames

by Devashish Chorey, Prasad Boggavarapu, Devendra Deshmukh, Ravikrishna Rayavarapu and Yogeshwar Nath Mishra

Photonics 2024, 11(2), 144; https://doi.org/10.3390/photonics11020144 - 4 Feb 2024

Viewed by 1147

Abstract

Snapshot multispectral imaging of chemical species in the flame is essential for improved understanding of the combustion process. In this article, we investigate the different configurations of a structured laser sheet-based multispectral imaging approach called the Frequency Recognition Algorithm for Multiple Exposures (FRAME). [...] Read more.

Snapshot multispectral imaging of chemical species in the flame is essential for improved understanding of the combustion process. In this article, we investigate the different configurations of a structured laser sheet-based multispectral imaging approach called the Frequency Recognition Algorithm for Multiple Exposures (FRAME). Using FRAME, a snapshot of Laser-Induced Fluorescence (LIF) of Polycyclic Aromatic Hydrocarbons (PAH) excited by 283.5 nm laser and Laser-Induced Incandescence (LII) of soot particles excited by 532 nm laser are acquired simultaneously on a single FRAME image. A laminar diffusion flame of acetylene produced by a Gülder burner is used for the experiments. The standard FRAME approach is based on creating two spatially modulated laser sheets and arranging them in a cross-patterned configuration (X). However, the effect of using different configurations (angles) of the two laser sheets on the multispectral planar imaging of the flame has not yet been studied. Therefore, we have compared the FRAME approach in four different configurations while keeping the same flame conditions. First, we have compared the relation between laser fluence and LII signals with and without spatial modulation of the 532 nm laser sheet and found that both detections follow the same curve. When comparing the maps of flame species reconstructed from the standard FRAME configuration and other configurations, there are some dissimilarities. These differences are attributed to minor changes in the imaging plane, optical alignment, laser path length, different modulation frequencies of the laser sheet, laser extinction, laser fluence, etc. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

13 pages, 2483 KiB

Open AccessArticle

Dynamic Micro-Vibration Measurement Based on Orbital Angular Momentum

by Jialong Zhu, Fucheng Zou, Le Wang and Shengmei Zhao

Photonics 2024, 11(1), 27; https://doi.org/10.3390/photonics11010027 - 28 Dec 2023

Viewed by 1298

Abstract

In this study, we introduce a novel approach for dynamic micro-vibration measurement, employing an Orbital Angular Momentum (OAM) interferometer, where the reference beam is Gaussian (GS) and the measurement beam is OAM. The OAM light reflected back from the target carries information about [...] Read more.

In this study, we introduce a novel approach for dynamic micro-vibration measurement, employing an Orbital Angular Momentum (OAM) interferometer, where the reference beam is Gaussian (GS) and the measurement beam is OAM. The OAM light reflected back from the target carries information about the target’s vibrations. The interference of the OAM light with Gaussian light generates petal-shaped patterns, and the target’s vibration information can be measured by detecting the rotation angle of these petals. Our proposed method demonstrates enhanced tolerance to misalignment and superior precision. The effects of vibration frequency, CCD frame rates, and Topological Charges (TCs) on measurement accuracy are analyzed thoroughly. Experimental results reveal that the proposed method offers a higher accuracy (up to 22.34 nm) and an extended measurement range of (0–800 cm). These capabilities render our technique highly suitable for applications demanding nanometer-scale resolution in various fields, including precision engineering and advanced optical systems. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

12 pages, 5292 KiB

Open AccessArticle

Extension of Fiber Bragg Grating Ultrasound Sensor Network by Adhesive Couplers

by Jee-Myung Kim, Sherif Aboubakr and Kara Peters

Photonics 2023, 10(12), 1366; https://doi.org/10.3390/photonics10121366 - 12 Dec 2023

Cited by 1 | Viewed by 1359

Abstract

Previous studies demonstrated coupling of acoustic guided waves from one optical fiber to another through a simple adhesive bond coupler. This paper experimentally utilizes such an adhesive bond coupler to easily extend an already existing sensor network. We experimentally demonstrate this concept for [...] Read more.

Previous studies demonstrated coupling of acoustic guided waves from one optical fiber to another through a simple adhesive bond coupler. This paper experimentally utilizes such an adhesive bond coupler to easily extend an already existing sensor network. We experimentally demonstrate this concept for detecting simulated cracks growing from circular holes in a thin aluminum plate. A single, remotely bonded FBG sensor is used to detect the original crack growth, followed by the addition of other optical fiber segments using adhesive couplers to detect new crack growth locations on the plate. A laser Doppler vibrometer is also used to measure the guided wave propagation through the plate to verify that the changes in the FBG sensor measurements are due to the growth of the cracks. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

13 pages, 4872 KiB

Open AccessArticle

Design and Experimental Validation of an Optical Autofocusing System with Improved Accuracy

by Jui-Hsiang Hung, Ho-Da Tu, Wen-Huai Hsu and Chien-Sheng Liu

Photonics 2023, 10(12), 1329; https://doi.org/10.3390/photonics10121329 - 30 Nov 2023

Cited by 2 | Viewed by 1486

Abstract

This study proposes a modified optical design to improve the issue of autofocus accuracy in existing optical systems. The proposed system uses lens offset to convert incident light into non-parallel light, achieving a focus shift and avoiding severe deformation of the light spot [...] Read more.

This study proposes a modified optical design to improve the issue of autofocus accuracy in existing optical systems. The proposed system uses lens offset to convert incident light into non-parallel light, achieving a focus shift and avoiding severe deformation of the light spot near the focal point of the objective lens. Based on triangulation theory and optical focusing theories such as the centroid method, the proposed optical design improves the shortcomings of existing technology. Experimental results demonstrate that the proposed optical autofocusing system has better autofocus accuracy than traditional systems while also reducing the difficulty of image processing. In summary, the proposed optical system is not only an effective autofocusing technology but also a highly valuable optical inspection and industrial application technology. This system has broader application and development opportunities for future research and practice. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

15 pages, 12151 KiB

Open AccessArticle

Measurement Method for the Flight Parameters of a Small Flying Object Using a Multi-Dimensional LED Detection Array

by Tao Dong, Siqi Li, Ding Chen and Ziyu Yang

Photonics 2023, 10(12), 1313; https://doi.org/10.3390/photonics10121313 - 28 Nov 2023

Viewed by 1088

Abstract

This article proposes a measurement method using a multi-dimensional LED detection array, which can be used to obtain the flight parameters (i.e., impact coordinates, flight velocity, and incident angle) of a small flying object. Firstly, the composition of the proposed system and its [...] Read more.

This article proposes a measurement method using a multi-dimensional LED detection array, which can be used to obtain the flight parameters (i.e., impact coordinates, flight velocity, and incident angle) of a small flying object. Firstly, the composition of the proposed system and its detection principle are described in detail. Then, a calculation model is derived according to the geometrical relationship between the different LED detection arrays, which can calculate the above flight parameters. Furthermore, numerical simulations are performed to analyze the change trend in the measurement error of the proposed system, and it can be verified that its measurement performance meets the related requirements in theory. Finally, we use the proposed system and a high-speed camera system to carry out comparison experiments with two different reference velocities of 900 m/s and 700 m/s, and the results show that the maximum deviation in the measured absolute velocity is always less than 1 m/s and that the maximum deviations of the measured coordinates of x and y are not more than 2 mm within the effective measurement range. Therefore, the proposed measurement method is feasible and effective, and it can also meet the requirements of the measurement system. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

14 pages, 1694 KiB

Open AccessArticle

Multiplexing Quantum and Classical Channels of a Quantum Key Distribution (QKD) System by Using the Attenuation Method

by Ondrej Klicnik, Petr Munster and Tomas Horvath

Photonics 2023, 10(11), 1265; https://doi.org/10.3390/photonics10111265 - 16 Nov 2023

Cited by 3 | Viewed by 1696

Abstract

The primary goal in this paper is to verify the possibility of combining a quantum channel into a single optical fiber with other classical channels by using the so-called attenuation method. Since the quantum channel is very weak in terms of power, combining [...] Read more.

The primary goal in this paper is to verify the possibility of combining a quantum channel into a single optical fiber with other classical channels by using the so-called attenuation method. Since the quantum channel is very weak in terms of power, combining it into a single fiber with much more powerful classical channels is challenging. Thus, sufficiently high-quality filtering is important to avoid possible crosstalk. A second and more difficult problem to address is the interference caused by Raman noise, which increases with the fiber length and is also dependent on the input power of the classical channel. Thus, in this paper the focus is on the possibility of suppressing the Raman noise effect, both in advance by means of wavelength positioning and by means of installed optical components. Such phenomena must be considered in the route design, as the quantum channel must be placed at a suitable wavelength with respect to the classical channels. The influence of other nonlinear phenomena has been neglected. In this paper, a practical experiment aimed at building a fully functional multiplexed quantum key distribution link is also described. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

7 pages, 4541 KiB

Open AccessCommunication

Multi-Frequency Doppler Velocimetry Based on a Mode-Locked Distributed Bragg Reflector Laser

by Hao Song, Dan Lu, Zhihao Zhang, Fei Guo, Daibing Zhou and Lingjuan Zhao

Photonics 2023, 10(11), 1254; https://doi.org/10.3390/photonics10111254 - 13 Nov 2023

Viewed by 1350

Abstract

A differential multi-frequency laser Doppler velocimetry is demonstrated, utilizing the synchronized multimode of a mode-locked distributed Bragg reflector laser. This scheme enables the simultaneous detection of multiple Doppler frequency shifts. Multiple differential Doppler shifts of 0.6 Hz, 1.3 Hz, and 1.9 Hz are [...] Read more.

A differential multi-frequency laser Doppler velocimetry is demonstrated, utilizing the synchronized multimode of a mode-locked distributed Bragg reflector laser. This scheme enables the simultaneous detection of multiple Doppler frequency shifts. Multiple differential Doppler shifts of 0.6 Hz, 1.3 Hz, and 1.9 Hz are obtained, with an average speed of 3.677 mm/s and a standard deviation of 0.122 mm/s, demonstrating a cross-referenced velocity measurement capability. The measurement results are also compared with the dual-frequency laser Doppler velocimetry scheme using electro-optical modulation. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

10 pages, 3989 KiB

Open AccessArticle

Image Reconstruction and Investigation of Factors Affecting the Hue and Wavelength Relation Using Different Interpolation Algorithms with Raw Data from a CMOS Sensor

by Eun-Min Kim, Kyung-Kwang Joo and Hyeon-Woo Park

Photonics 2023, 10(11), 1216; https://doi.org/10.3390/photonics10111216 - 31 Oct 2023

Viewed by 1116

Abstract

An image processing method was employed to obtain wavelength information using light irradiated during camera exposure. Physically, hue (H) and wavelength (W) are closely related. Once the H value is known through image pixel analysis, the wavelength can be obtained. In this paper, [...] Read more.

An image processing method was employed to obtain wavelength information using light irradiated during camera exposure. Physically, hue (H) and wavelength (W) are closely related. Once the H value is known through image pixel analysis, the wavelength can be obtained. In this paper, the H-W curve was investigated from 400 to 650 nm using raw image data with a complementary metal oxide semiconductor (CMOS) sensor technology. We reconstructed the H-W curve from raw image data based on a demosaicing method with 2 × 2 pixel images. To date, no study has reported on reconstructing the H-W curve using several different interpolation algorithms in the 400~650 nm wavelength region. In addition, several factors affecting the H-W curve with a raw digital image, such as exposure time, aperture, and international organization for standardization (ISO) settings, were investigated for the first time. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

Review

Jump to: Research

18 pages, 1507 KiB

Open AccessReview

Advances in Lensless Fluorescence Microscopy Design

by Somaiyeh Khoubafarin, Edmond Kwesi Dadson and Aniruddha Ray

Photonics 2024, 11(6), 575; https://doi.org/10.3390/photonics11060575 - 19 Jun 2024

Viewed by 1287

Abstract

Lensless fluorescence microscopy (LLFM) has emerged as a promising approach for biological imaging, offering a simplified, high-throughput, portable, and cost-effective substitute for conventional microscopy techniques by removing lenses in favor of directly recording fluorescent light on a digital sensor. However, there are several [...] Read more.

Lensless fluorescence microscopy (LLFM) has emerged as a promising approach for biological imaging, offering a simplified, high-throughput, portable, and cost-effective substitute for conventional microscopy techniques by removing lenses in favor of directly recording fluorescent light on a digital sensor. However, there are several obstacles that this novel approach must overcome, such as restrictions on the resolution, field-of-view (FOV), signal-to-noise ratio (SNR), and multicolor-imaging capabilities. This review looks at the most current developments aimed at addressing these challenges and enhancing the performance of LLFM systems. To address these issues, computational techniques, such as deconvolution and compressive sensing, hardware modifications and structured illumination, customized filters, and the utilization of fiber-optic plates, have been implemented. Finally, this review emphasizes the numerous applications of LLFM in tissue analysis, pathogen detection, and cellular imaging, highlighting its adaptability and potential influence in a range of biomedical research and clinical diagnostic areas. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

20 pages, 4240 KiB

Open AccessReview

Generation of Orbital Angular Momentum Light by Patterning Azopolymer Thin Films

by Temitope M. Olaleye, Maria Raposo and Paulo A. Ribeiro

Photonics 2023, 10(12), 1319; https://doi.org/10.3390/photonics10121319 - 29 Nov 2023

Viewed by 1732

Abstract

Orbital angular momentum (OAM) encoding is a promising technique to boost data transmission capacity in optical communications. Most recently, azobenzene films have gained attention as a versatile tool for creating and altering OAM-carrying beams. Unique features of azobenzene films make it possible to [...] Read more.

Orbital angular momentum (OAM) encoding is a promising technique to boost data transmission capacity in optical communications. Most recently, azobenzene films have gained attention as a versatile tool for creating and altering OAM-carrying beams. Unique features of azobenzene films make it possible to control molecular alignment through light-induced isomerization about the azo bond. This feature enables the fabrication of diffractive optical devices such as spiral phase plates and holograms by accurately imprinting a phase profile on the incident light. By forming azobenzene sheets into diffractive optical elements, such as spiral phase plates, one can selectively create OAM-carrying beams. Due to the helical wavefront and phase variation shown by these beams, multiple distinct channels can be encoded within a single optical beam. This can significantly increase the data transmission capacity of optical communication systems with this OAM multiplexing technique. Additionally, holographic optical components made from azobenzene films can be used to build and reconstruct intricate wavefronts. It is possible to create OAM-based holograms by imprinting holographic designs on azobenzene films, which makes it simpler to control and shape optical beams for specific communication requirements. In addition, azobenzene-based materials can then be suitable for integration into optical communication devices because of their reconfigurability, compactness, and infrastructure compatibility, which are the main future perspectives for achieving OAM-based technologies for the next generation, among other factors. In this paper, we see the possible use of azobenzene films in the generation and modification of OAM beams for optical communications through light-induced isomerization. In addition, the potential role of azobenzene films in the development of novel OAM-based devices that paves the way for the realization of high-capacity, OAM-enabled optical communication networks are discussed. Full article

(This article belongs to the Special Issue Advanced Photonic Sensing and Measurement II)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Advanced Photonic Sensing and Measurement II

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (27 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI