Photonics

11 pages, 5150 KiB

Open AccessCommunication

Analog–Digital Combined High-Secure Optical Communication System Based on Chaotic Circuit Driving

by Qing Zhong, Bo Liu, Jianxin Ren, Yicheng Jiang, Rahat Ullah, Zhiruo Guo, Yaya Mao, Xiangyu Wu, Yongfeng Wu, Lilong Zhao and Tingting Sun

Photonics 2022, 9(9), 669; https://doi.org/10.3390/photonics9090669 - 19 Sep 2022

Cited by 2 | Viewed by 1461

Abstract

We propose and demonstrate a new analog–digital combined high-secure optical communication system based on chaotic circuit driving, which achieves encryption in the analog and digital domains. A 3D chaotic system is used for analog domain phase encryption (ADPE) and digital domain time–frequency encryption [...] Read more.

We propose and demonstrate a new analog–digital combined high-secure optical communication system based on chaotic circuit driving, which achieves encryption in the analog and digital domains. A 3D chaotic system is used for analog domain phase encryption (ADPE) and digital domain time–frequency encryption (DDTFE) simultaneously. The ADPE is carried out by the privately chaotic signal driving the phase modulator (PM), which realizes chaotic phase encryption. The chaotic circuit comprehends highly complex nonlinear dynamics. Its size is 10 cm × 5 cm, which has the characteristics of small size and low cost. The DDTFE is performed by the frequency–time encryption of signals in the digital domain. The experimental results show that the optical physical layer encryption scheme based on analog and digital combination can successfully mask the original data. The driving signal of PM is that generated by the chaotic circuit and needs to be privately synchronized, so that the legal receiver may accurately decrypt the encrypted data and the eavesdropper is unable to intercept a valuable message. If the chaotic driving circuit produces a delay of 3 s, the bit error rate (BER) reaches more than 0.3 at the receiver. The results of experiment verify that the scheme can transmit 13.3 Gb/s 16 quadrature amplitude modulation orthogonal frequency division multiplexing (16QAM-OFDM) signal over 25 km standard single mode fiber (SSMF). This scheme achieves low-cost, high-security communication, making it a suitable foundation for high-speed, secure optical communication at the physical layer. Full article

(This article belongs to the Special Issue Optical Fiber Communication Systems)

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18 pages, 4010 KiB

Open AccessArticle

Fluorescence Quenching of Carboxy-Substituted Phthalocyanines Conjugated with Nanoparticles under High Stoichiometric Ratios

by Daniil A. Gvozdev, Alexei E. Solovchenko, Alexander G. Martynov, Aleksei V. Yagodin, Marina G. Strakhovskaya, Yulia G. Gorbunova and Eugene G. Maksimov

Photonics 2022, 9(9), 668; https://doi.org/10.3390/photonics9090668 - 19 Sep 2022

Cited by 2 | Viewed by 1246

Abstract

Background: The search of the approaches towards a photosensitizer’s conjugation with multifunctional nanoparticles is an important step in the development of photodynamic therapy techniques. Association of photosensitizer molecules with nanoparticles that perform the delivery function can lead to a change in the functional [...] Read more.

Background: The search of the approaches towards a photosensitizer’s conjugation with multifunctional nanoparticles is an important step in the development of photodynamic therapy techniques. Association of photosensitizer molecules with nanoparticles that perform the delivery function can lead to a change in the functional state of the photosensitizer. Methods: We studied the effects observed upon incorporation of octa- and hexadeca-carboxyphthalocyanines of zinc(II) and aluminum(III) (Pcs) into the polymer shell of nanoparticles with a semiconductor CdSe/CdS/ZnS core with various spectral and optical methods. Results: First, the interaction of Pc with the polymer shell leads to a change in the spectral properties of Pc; the effect strongly depends on the structure of the Pc molecule (number of carboxyl groups as well as the nature of the central cation in the macrocycle). Secondly, upon incorporation of several Pc molecules, concentration effects become significant, leading to Pc aggregation and/or nonradiative energy transfer between neighboring Pc molecules within a single nanoparticle. Conclusions: These processes lead to the decrease of a number of the Pc molecules in an excited state. Such effects should be taken into account during the development of multifunctional platforms for the delivery of photosensitizers, including the use of nanoparticles as enhancers of photosensitizer activity by energy transfer. Full article

(This article belongs to the Section Biophotonics and Biomedical Optics)

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9 pages, 3684 KiB

Open AccessCommunication

Generation of Photonic Hooks under Point-Source Illumination from Patchy Microcylinders

by Qingqing Shang, Chu Xu, Fen Tang, Jiaji Li, Yao Fan, Caojin Yuan, Zengbo Wang, Chao Zuo and Ran Ye

Photonics 2022, 9(9), 667; https://doi.org/10.3390/photonics9090667 - 19 Sep 2022

Cited by 3 | Viewed by 1393

Abstract

Photonic hook (PH) is a new type of non-evanescent light beam with subwavelength curved structures. It has shown promising applications in super-resolution imaging and has the potential to be used in micromachining, optical trapping, etc. PHs are generally produced by illuminating mesoscale asymmetric [...] Read more.

Photonic hook (PH) is a new type of non-evanescent light beam with subwavelength curved structures. It has shown promising applications in super-resolution imaging and has the potential to be used in micromachining, optical trapping, etc. PHs are generally produced by illuminating mesoscale asymmetric particles with optical plane waves. In this work, we used the finite-difference time-domain (FDTD) method to investigate the PH phenomenon under point-source illumination. We found that the PHs can be effectively generated from point-source illuminated patchy particles. By changing the background refractive index, particle diameters and the position and coverage ratio of Ag patches, the characteristics of the PHs can be effectively tuned. Moreover, the structure of the intensity distribution of the light field generated from small and large particles can have an opposite bending direction due to the near-field light-matter interaction. Full article

(This article belongs to the Special Issue Extreme Photonics)

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12 pages, 12941 KiB

Open AccessArticle

Photonic Measurement for Doppler Frequency Shift and Angle of Arrival Based on a Dual-Polarization Dual-Drive Mach–Zehnder Modulator

by Qingqing Meng, Tao Lin, Zihang Zhu, Guodong Wang, He Li, Xuan Li, Longqiang Yu and Shanghong Zhao

Photonics 2022, 9(9), 666; https://doi.org/10.3390/photonics9090666 - 18 Sep 2022

Cited by 1 | Viewed by 1465

Abstract

A novel photonic-assisted system for realizing the simultaneous measurement of Doppler frequency shift (DFS) and angle of arrival (AOA) is proposed. It is a simplified structure that is based on a dual-polarization dual-drive Mach–Zehnder modulator (DPol-DDMZM). The DFS direction can be accurately determined [...] Read more.

A novel photonic-assisted system for realizing the simultaneous measurement of Doppler frequency shift (DFS) and angle of arrival (AOA) is proposed. It is a simplified structure that is based on a dual-polarization dual-drive Mach–Zehnder modulator (DPol-DDMZM). The DFS direction can be accurately determined by comparing the phase relationship between the upper and lower low-frequency signal waveforms. An amplitude comparison function (ACF), which constructs a one-to-one mapping between the power ratio and the phase difference of echo microwave signals, can reduce the AOA measurement errors. The simulation results show that the simulated ACFs agree well with the theoretical ACFs, and the measurement errors of AOA are less than ±2.8° in a range of 0° to 78°. Moreover, the DFS can be realized by analyzing the spectrum of the low-frequency electrical signal with a measurement error of less than ±0.05 Hz. The system structure is compact and cost-effective, which provides an alternative solution for modern radar and electronic warfare receivers. Full article

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12 pages, 6050 KiB

Open AccessArticle

Sub-5 nm AFM Tip Characterizer Based on Multilayer Deposition Technology

by Ziruo Wu, Yingfan Xiong, Lihua Lei, Wen Tan, Zhaohui Tang, Xiao Deng, Xinbin Cheng and Tongbao Li

Photonics 2022, 9(9), 665; https://doi.org/10.3390/photonics9090665 - 17 Sep 2022

Cited by 2 | Viewed by 1257

Abstract

Atomic force microscope (AFM) is commonly used for three-dimensional characterization of the surface morphology of structures at nanoscale, but the “Inflation effect” of the tip is an important factor affecting the accuracy. A tip characterizer has the advantages of in situ measurement, higher [...] Read more.

Atomic force microscope (AFM) is commonly used for three-dimensional characterization of the surface morphology of structures at nanoscale, but the “Inflation effect” of the tip is an important factor affecting the accuracy. A tip characterizer has the advantages of in situ measurement, higher accuracy of probe inversion results, and relatively simple fabrication process. In this paper, we developed a rectangular tip characterizer based on multilayer film deposition technology with protruding critical dimension parts and grooves parts. And the tip characterization is highly consistent across the line widths and grooves, and still performs well even in the sub-5 nm line width tip characterizer. This indicates that tip characterizers produced by this method can synergistically meet the combined requirements of standard rectangular structure, very small line edge roughness, very small geometry dimension, and traceable measurements. Full article

(This article belongs to the Special Issue Recent Advances in Optical Thin Films)

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9 pages, 2765 KiB

Open AccessArticle

High Performance Planar Antimony-Based Superlattice Photodetectors Using Zinc Diffusion Grown by MBE

by Jiakai Li, R. K. Saroj, Steven Slivken, V. H. Nguyen, Gail Brown and Manijeh Razeghi

Photonics 2022, 9(9), 664; https://doi.org/10.3390/photonics9090664 - 16 Sep 2022

Viewed by 1646

Abstract

In this letter, we report a mid-wavelength infrared (MWIR) planar photodetector based on InAs/InAs_1−xSb_x type-II superlattices (T2SLs) that has a cut-off wavelength of 4.3 μm at 77 K. The superlattice for the device was grown by molecular beam epitaxy while [...] Read more.

In this letter, we report a mid-wavelength infrared (MWIR) planar photodetector based on InAs/InAs_1−xSb_x type-II superlattices (T2SLs) that has a cut-off wavelength of 4.3 μm at 77 K. The superlattice for the device was grown by molecular beam epitaxy while the planar device structure was achieved by Zinc diffusion process in a metal–organic chemical vapor deposition reactor. At 77 K, the peak responsivity and the corresponding quantum efficiency had the value of 1.42 A/W and 48% respectively at 3.7 μm under −20 mV for the MWIR planar photodetector. At 77 K, the MWIR planar photodetector exhibits a dark current density of 2.0 × 10⁻⁵ A/cm² and the R₀A value of ~3.0 × 10² Ω∙cm² under −20 mV, which yielded a specific detectivity of 4.0 × 10¹¹ cm·Hz^1/2/W at 3.7 μm. At 150 K, the planar device showed a dark current density of 6.4 × 10⁻⁵ A/cm² and a quantum efficiency of 49% at ~3.7 μm under −20 mV, which yielded a specific detectivity of 2.0 × 10¹¹ cm·Hz^1/2/W. Full article

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7 pages, 3424 KiB

Open AccessCommunication

Power Loss Reduction of Angled Metallic Wedge Plasmonic Waveguides via the Interplay between Near-Field Optical Coupling and Modal Coupling

by Yin-Song Liao, Jia-Ren Wu, Diksha Thakur, Jy-Shan Hsu, Ram Prakash Dwivedi and Sheng Hsiung Chang

Photonics 2022, 9(9), 663; https://doi.org/10.3390/photonics9090663 - 16 Sep 2022

Viewed by 1149

Abstract

Coupled metallic-wedge nano-plasmonic (CWP) waveguides were predicted as the best building blocks, which can realize ultra-compact and broadband integrated optical circuits (IOCs) due to the localized near-field distributions at the dielectric/metal interfaces. Our simulation results show that the manipulations of the near-field distribution [...] Read more.

Coupled metallic-wedge nano-plasmonic (CWP) waveguides were predicted as the best building blocks, which can realize ultra-compact and broadband integrated optical circuits (IOCs) due to the localized near-field distributions at the dielectric/metal interfaces. Our simulation results show that the manipulations of the near-field distribution and the near-field modal coupling in CWP waveguides can effectively minimize the power loss by varying the wedge angles, which can avoid the loss from the metallic structure and thereby improving the practical application in IOCs. Full article

(This article belongs to the Section Quantum Photonics and Technologies)

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15 pages, 6037 KiB

Open AccessArticle

Ultrashort Laser Pulse Focusing by Amplitude and Phase Zone Plates

by Elena Kozlova and Victor Kotlyar

Photonics 2022, 9(9), 662; https://doi.org/10.3390/photonics9090662 - 16 Sep 2022

Cited by 1 | Viewed by 1283

Abstract

In this paper, using the frequency-dependent finite-difference time-domain method, a femtosecond cylindrical vector beam of second-order focusing binary zone plates (BZP) is investigated. It is shown that the relief material has a significant effect on the electromagnetic field formed in the focal plane. [...] Read more.

In this paper, using the frequency-dependent finite-difference time-domain method, a femtosecond cylindrical vector beam of second-order focusing binary zone plates (BZP) is investigated. It is shown that the relief material has a significant effect on the electromagnetic field formed in the focal plane. It is also shown that, in the case of tight focusing of a second-order cylindrically polarized laser pulse, a reverse energy flux is formed in the focus near the optical axis. For the quartz BZP, the energy backflow is maximum. For aluminum and chromium BZPs, the reverse energy flux is approximately two times less, and there is no energy backflow in the focus formed by the gold BZP. This study will be useful for surface nanostructuring applications where a focused short pulse is applied. Full article

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12 pages, 5305 KiB

Open AccessArticle

Fiber Optic Sensor with a Gold Nanowire Group Array for Broad Range and Low Refractive Index Detection

by Gongli Xiao, Jiapeng Su, Hongyan Yang, Zetao Ou, Haiou Li, Xingpeng Liu, Zanhui Chen, Yunhan Luo and Jianqing Li

Photonics 2022, 9(9), 661; https://doi.org/10.3390/photonics9090661 - 16 Sep 2022

Cited by 6 | Viewed by 1799

Abstract

To achieve high performance and wide range detection, we propose an ultra-wide range high sensitivity plasmonic fiber optic sensor with a gold (Au) nanowire group array, which has both propagating surface plasmon resonance (PSPR) and local surface plasmon resonance (LSPR) sensing characteristics. The [...] Read more.

To achieve high performance and wide range detection, we propose an ultra-wide range high sensitivity plasmonic fiber optic sensor with a gold (Au) nanowire group array, which has both propagating surface plasmon resonance (PSPR) and local surface plasmon resonance (LSPR) sensing characteristics. The PSPR, LSPR, and PSPR+LSPR are presented as Au thin layers, Au spheres (or Au nanowires), and Au nanowire group arrays, respectively, and their respective properties are analyzed from theoretical, simulated, and numerical aspects. When detection is performed, the presence of both evanescent wave and electric field forces in the Au nanowire group array combines to significantly improve the sensor’s detection capability. Detection simulation analysis was performed using COMSOL Multiphysics software. The range of refractive indices that can be detected is 1.08 to 1.37 in the optical band from 1210 nm to 2140 nm. In the detection range, the maximum sensitivity of the detected wavelength is 13,000 nm/RIU. Our proposed sensor has a broad range, high sensitivity, and low refractive index detection, and has good research value and application prospects. Full article

(This article belongs to the Special Issue Design and Application of Modern Evanescent Wave Photonic Sensors)

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9 pages, 1238 KiB

Open AccessCommunication

Detection of Hemoglobin Concentration Based on Defective One-Dimensional Photonic Crystals

by Shiju Edappadikkunnummal, Rahul Chembra Vasudevan, Sruthy Dinesh, Sheenu Thomas, Narayana Rao Desai and Sharafudeen Kaniyarakkal

Photonics 2022, 9(9), 660; https://doi.org/10.3390/photonics9090660 - 16 Sep 2022

Cited by 8 | Viewed by 1521

Abstract

The significance of the optical biosensor is its ability to detect biomolecules in their natural form. Among them, photonic crystal-based biosensors analyze the refractive index changes due to molecular interaction, and that is correlated to the sample concentration instead of sample mass. In [...] Read more.

The significance of the optical biosensor is its ability to detect biomolecules in their natural form. Among them, photonic crystal-based biosensors analyze the refractive index changes due to molecular interaction, and that is correlated to the sample concentration instead of sample mass. In this paper, we report the sensing performance of a one-dimensional photonic crystal-based sensor for the detection of hemoglobin concentration using an asymmetric periodic structure with a single defect. We have used the transfer matrix method to analyze the reflectance properties of the photonic crystal. The resonant dip in the spectra and its shift with hemoglobin concentration is the basis of our sensor design. The proposed sensor is efficient in sensing hemoglobin concentration, the sensitivity and other sensor parameters were derived numerically, and the obtained parameters are comparable to the many of the reported values of photonic crystal-based sensors. The dependence of the defect layer thickness on the position of resonant dips and sensitivity is also demonstrated in our work. The numerical results prove that these photonic crystal biosensors are simple, cost effective and highly accurate for detecting the hemoglobin concentration. Full article

(This article belongs to the Special Issue Optical Sensing)

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7 pages, 2481 KiB

Open AccessCommunication

Scotch-Tape and Graphene-Oxide Photomobile Polymer Film

by Riccardo Castagna, Andrea Di Donato, Rachele Castaldo, Roberto Avolio, Oriano Francescangeli and Daniele Eugenio Lucchetta

Photonics 2022, 9(9), 659; https://doi.org/10.3390/photonics9090659 - 15 Sep 2022

Cited by 2 | Viewed by 1306

Abstract

In this work, we report on the fabrication and photonic activation of a novel kind of photomobile polymer (PMP) film based mainly on a double layered asymmetric configuration. The PMP is cheap and extremely easy to make. It is made of PVC/isoprene tape [...] Read more.

In this work, we report on the fabrication and photonic activation of a novel kind of photomobile polymer (PMP) film based mainly on a double layered asymmetric configuration. The PMP is cheap and extremely easy to make. It is made of PVC/isoprene tape with a layer of graphene-oxide (GO) attached. Under illumination at different intensities, and with coherent and incoherent light sources, the bending of the PMP film changes considerably. In particular, we noticed a more efficient bending effect when the film is directly exposed to high light intensities or to NIR radiation in the case of incoherent light sources. For the exposure times used in our experiments, the process is completely reversible when the light source is switched off. Additionally, if we paint the side of the PVC tape exposed to light black, the film is not able to return to its starting position and the bending results are permanent. This suggests that the presence of the GO-layer is responsible for the restoration of the position of the PMP film. Full article

(This article belongs to the Section Optoelectronics and Optical Materials)

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14 pages, 3127 KiB

Open AccessCommunication

An Optical Front-End for Wideband Transceivers Based on Photonic Time Compression and Stretch

by Yukang Zhang and Hao Chi

Photonics 2022, 9(9), 658; https://doi.org/10.3390/photonics9090658 - 15 Sep 2022

Viewed by 1413

Abstract

This study proposes an optical front-end for wideband transceivers based on photonic time compression (PTC) and photonic time stretch (PTS) techniques. The PTC and PTS systems within a transceiver generate and receive wideband RF signals, respectively, which expand the processible signal bandwidth. We [...] Read more.

This study proposes an optical front-end for wideband transceivers based on photonic time compression (PTC) and photonic time stretch (PTS) techniques. The PTC and PTS systems within a transceiver generate and receive wideband RF signals, respectively, which expand the processible signal bandwidth. We present analytical models for characterizing the optical front-end based on the PTC and PTS. The design of the front-end for signal generation and reception is also discussed, in which we emphasize the bandwidth match between the PTC-based transmitter and PTS-based receiver through an appropriate dispersion configuration. We conducted experiments on PTC and PTS systems with a single channel. Further simulation results for PTC and PTS systems with multiple channels for continuous-time operation are presented. The proposed front-end based on time compression/stretch can largely improve the signal bandwidth in systems using inexpensive low-speed analogue/digital converters. Full article

(This article belongs to the Special Issue Microwave Photonics II)

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14 pages, 4807 KiB

Open AccessArticle

Low-Complexity and Highly-Robust Chromatic Dispersion Estimation for Faster-than-Nyquist Coherent Optical Systems

by Tao Yang, Yu Jiang, Yongben Wang, Jialin You, Liqian Wang and Xue Chen

Photonics 2022, 9(9), 657; https://doi.org/10.3390/photonics9090657 - 15 Sep 2022

Cited by 2 | Viewed by 1238

Abstract

Faster-than-Nyquist (FTN) coherent optical transmission technology is considered to be an outstanding solution to achieve higher spectral efficiency (SE), larger capacity, and greater achievable transmission by using advanced modulation formats in concert with highly efficient digital signal processing (DSP) to estimate and compensate [...] Read more.

Faster-than-Nyquist (FTN) coherent optical transmission technology is considered to be an outstanding solution to achieve higher spectral efficiency (SE), larger capacity, and greater achievable transmission by using advanced modulation formats in concert with highly efficient digital signal processing (DSP) to estimate and compensate various impairments. However, severe inter-symbol interference (ISI) caused by tight FTN pulse shaping will lead to intractable chromatic dispersion (CD) estimation problems, as existing conventional methods are completely ineffective or exhibit unaffordable computational complexity (CC). In this paper, we propose a low-complexity and highly robust scheme that could realize accurate and reliable CD estimation (CDE) based on a designed training sequence (TS) in the first stage and an optimized fractional Fourier transform (FrFT) in the second stage. The training sequence with the designed structure helps us to estimate CD roughly but reliably, and it further facilitates the FrFT in the second stage to achieve accurate CDE within a narrowed searching range; it thereby results in very low CC. Comprehensive simulation results of triple-carrier 64-GBaud FTN dual-polarization 16-ary quadrature amplitude modulation (DP-16QAM) systems demonstrate that, with only overall 3% computational complexity compared with conventional blind CDE methods, the proposed scheme exhibits a CDE accuracy better than 65 ps/nm even under an acceleration factor as low as 0.85. In addition, 60-GBaud FTN DP quadrature phase shift keying (DP-QPSK)/16QAM transmission experiments are carried out, and the results show that the CDE error is less than 70 ps/nm. The advantages of the proposed scheme make it a preferable candidate for CDE in practical FTN coherent optical systems. Full article

(This article belongs to the Special Issue Photonics for Emerging Applications in Communication and Sensing)

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16 pages, 4081 KiB

Open AccessArticle

ReDDLE-Net: Reflectance Decomposition for Directional Light Estimation

by Jiangxin Yang, Binjie Ding, Zewei He, Gang Pan, Yanpeng Cao, Yanlong Cao and Qian Zheng

Photonics 2022, 9(9), 656; https://doi.org/10.3390/photonics9090656 - 15 Sep 2022

Cited by 1 | Viewed by 1295

Abstract

The surfaces of real objects can visually appear to be glossy, matte, or anywhere in between, but essentially, they display varying degrees of diffuse and specular reflectance. Diffuse and specular reflectance provides different clues for light estimation. However, few methods simultaneously consider the [...] Read more.

The surfaces of real objects can visually appear to be glossy, matte, or anywhere in between, but essentially, they display varying degrees of diffuse and specular reflectance. Diffuse and specular reflectance provides different clues for light estimation. However, few methods simultaneously consider the contributions of diffuse and specular reflectance for light estimation. To this end, we propose ReDDLE-Net, which performs Reflectance Decomposition for Directional Light Estimation. The primary idea is to take advantage of diffuse and specular clues and adaptively balance the contributions of estimated diffuse and specular components for light estimation. Our method achieves a superior performance advantage over state-of-the-art directional light estimation methods on the DiLiGenT benchmark. Meanwhile, the proposed ReDDLE-Net can be combined with existing calibrated photometric stereo methods to handle uncalibrated photometric stereo tasks and achieve state-of-the-art performance. Full article

(This article belongs to the Special Issue The Interplay between Photonics and Machine Learning)

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11 pages, 4683 KiB

Open AccessArticle

Probabilistically-Shaped DMT for IM-DD Systems with Low-Complexity Fast WHT-Based PDSP

by Yi Liu, Haimiao Long, Ming Chen, Yun Cheng and Taoyun Zhou

Photonics 2022, 9(9), 655; https://doi.org/10.3390/photonics9090655 - 15 Sep 2022

Cited by 1 | Viewed by 1349

Abstract

Transmission capacity and receiver sensitivity of an intensity-modulation direct detection (IM-DD) optical discrete multi-tone (DMT) system can be improved by using the probabilistically shaping (PS) technique. However, different probabilistic distributions will be required owing to the unbalanced signal-to-noise ratio (SNR) among data-carrying subcarriers [...] Read more.

Transmission capacity and receiver sensitivity of an intensity-modulation direct detection (IM-DD) optical discrete multi-tone (DMT) system can be improved by using the probabilistically shaping (PS) technique. However, different probabilistic distributions will be required owing to the unbalanced signal-to-noise ratio (SNR) among data-carrying subcarriers (SCs) induced by the imperfect frequency response of optical/electrical devices, which can increase the implementation complexity of the PS-DMT transceiver. In this work, different signal pre-processing schemes including pre-equalization, Walsh–Hadamard transform (WHT)-based full data-carrying SCs precoding (FDSP) and fast WHT-based partial data-carrying SCs precoding (PDSP) are investigated for SNR equalization in a short-reach PS-DMT transmission system. After transmission over 50 km single-mode fiber, the experimental results indicated that three pre-processed signals have almost the same generalized mutual information (GMI) performance and receiver sensitivity improvements. The proposed fast WHT-based PDSP scheme may be a good option for the implementation of the PS-DMT transmission systems with a large SC SNR fluctuation regarding computational complexity. Full article

(This article belongs to the Special Issue Photonics for Emerging Applications in Communication and Sensing)

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10 pages, 3279 KiB

Open AccessArticle

Analysis and Correction of the Crosstalk Effect in a Three-Axis SERF Atomic Magnetometer

by Yeguang Yan, Jixi Lu, Binquan Zhou, Kun Wang, Ziao Liu, Xiaoyu Li, Weiyi Wang and Gang Liu

Photonics 2022, 9(9), 654; https://doi.org/10.3390/photonics9090654 - 14 Sep 2022

Cited by 5 | Viewed by 1678

Abstract

Three-axis atomic magnetometers have an excellent advantage for determining the complete vector information of a magnetic field to be measured. However, the crosstalk effect, which leads to an error output on one axis owing to a magnetic field on the other axes, can [...] Read more.

Three-axis atomic magnetometers have an excellent advantage for determining the complete vector information of a magnetic field to be measured. However, the crosstalk effect, which leads to an error output on one axis owing to a magnetic field on the other axes, can reduce the measurement accuracy. In this study, we propose an effective suppression method for the crosstalk effect in a three-axis atomic magnetometer. First, we investigated and analyzed the main factors that introduce the effect. Based on this, the modulation parameters were optimized to improve the scale factors, which obtained a coupling coefficient of less than 6% for the atomic magnetometer. Subsequently, the associated transfer matrix was corrected to further suppress the crosstalk effect. After correction, all the coupling coefficients were decreased to less than 3%, with the majority being lower than 1%. Full article

(This article belongs to the Section Lasers, Light Sources and Sensors)

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12 pages, 3120 KiB

Open AccessCommunication

CGA-VLP: High Accuracy Visible Light Positioning Algorithm Using Single Square LED with Geomagnetic Angle Correction

by Chen Yang, Shangsheng Wen, Danlan Yuan, Junye Chen, Junlin Huang and Weipeng Guan

Photonics 2022, 9(9), 653; https://doi.org/10.3390/photonics9090653 - 14 Sep 2022

Cited by 8 | Viewed by 1837

Abstract

Visible light positioning (VLP), benefiting from its high accuracy and low cost, is a promising technology for indoor location-based services. In this article, the theoretical limits and error sources of traditional camera-based VLP systems are analyzed. To solve the problem that multiple LEDs [...] Read more.

Visible light positioning (VLP), benefiting from its high accuracy and low cost, is a promising technology for indoor location-based services. In this article, the theoretical limits and error sources of traditional camera-based VLP systems are analyzed. To solve the problem that multiple LEDs are required and auxiliary sensors are imperfect, a VLP system with a single square LED which can correct the geomagnetic angle obtained from a geomagnetic sensor is proposed. In addition, we conducted a static positioning experiment and a dynamic positioning experiment integrated with pedestrian dead reckoning on an Android platform to evaluate the effectiveness of the proposed method. According to the experimental results, when the horizontal distance between the camera and the center of the LED is less than 120 cm, the average positioning error can be retained within 10 cm and the average positioning time on the mobile phone is 39.64 ms. Full article

(This article belongs to the Special Issue Advances in Visible Light Communication)

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22 pages, 45170 KiB

Open AccessArticle

Design of High Peak Power Pulsed Laser Diode Driver

by Ching-Yao Liu, Chih-Chiang Wu, Li-Chuan Tang, Wei-Hua Chieng, Edward-Yi Chang, Chun-Yen Peng and Hao-Chung Kuo

Photonics 2022, 9(9), 652; https://doi.org/10.3390/photonics9090652 - 14 Sep 2022

Cited by 2 | Viewed by 6420

Abstract

This paper attempts to describe a laser diode driver circuit using the depletion mode gallium nitride high electron mobility transistor (D-mode GaN HEMT) to generate nanosecond pulses at a repetition rate up to 10 MHz from the vertical-cavity surface-emitting laser (VCSEL). The feature [...] Read more.

This paper attempts to describe a laser diode driver circuit using the depletion mode gallium nitride high electron mobility transistor (D-mode GaN HEMT) to generate nanosecond pulses at a repetition rate up to 10 MHz from the vertical-cavity surface-emitting laser (VCSEL). The feature of this driver circuit is a large instantaneous laser power output designed in the most efficient way. The design specifications include a pulse duration between 10 ns and 100 ns and a peak power up to above 100 W. The pulsed laser diode driver uses the D-mode GaN HEMT, which has very small C_oss difference between turn-on and turn-off states. The analysis is according to a laser diode model that is adjusted to match the VCSEL, made in National Yang Ming Chiao Tung University (NYCU). A design guide is summarized from the derivations and analysis of the proposed laser diode driver. According to the design guide, we selected the capacitor, resistor, and diode components to achieve 10 ns to 100 ns pulse duration for laser lighting. The experiment demonstrated that the maximum power-to-light efficiency can be as high as 86% and the maximum peak power can be 150 W, which matches the specifications of certain applications such as light detection and ranging (LiDAR). Full article

(This article belongs to the Special Issue Nanophotonics Pioneer: Prof. Dr. Dieter Bimberg ‘Green Photonics Networks: From VCSELs to Nanophotonics’)

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17 pages, 3862 KiB

Open AccessArticle

Ring Resonator Gap Determination Design Rule and Parameter Extraction Method for Sub-GHz Resolution Whole C-Band Si₃N₄ Integrated Spectrometer

by Gazi Mahamud Hasan, Peng Liu, Mehedi Hasan, Houman Ghorbani, Mohammad Rad, Eric Bernier and Trevor J. Hall

Photonics 2022, 9(9), 651; https://doi.org/10.3390/photonics9090651 - 14 Sep 2022

Cited by 2 | Viewed by 3159

Abstract

A panoramic ultra-high resolution photonic integrated circuit spectrometer is under development by the authors. The architecture comprises a tunable ring resonator (RR) stage and an AWG stage. The resolution defines the bandwidth of the RR, determined by the cross-coupled power and hence the [...] Read more.

A panoramic ultra-high resolution photonic integrated circuit spectrometer is under development by the authors. The architecture comprises a tunable ring resonator (RR) stage and an AWG stage. The resolution defines the bandwidth of the RR, determined by the cross-coupled power and hence the gap between the access and ring waveguides. The AWG channel frequency spacing determines the required free-spectral range (FSR) and hence the perimeter of the ring resonator. The specified <1 GHz resolution combined with an FSR of 50 GHz renders accurate simulation difficult, obstructing the design process. In this report, a simplified design rule to determine the minimum gap between straight access waveguides and a circular ring waveguide is proposed. Realistic assumptions such as the existence of local bisymmetry and adiabatic mode evolution throughout the coupling region permit a simple mode solver to determine the relationship between the cross-coupled power and the minimum gap size. A parameter extraction method is also formulated for add-drop rings equipped with two nominally identical couplers that disentangles the loss and coupling ring parameters from intensity-only transmission measurements. The proposed rule is applied to the design of ring resonators fabricated on a Si₃N₄ platform. The parameter extraction method is used to analyze the measured characterization data of the ring resonators. The results show good agreement within ~43 nm between the design rule and the gaps size determined by the parameters extracted from the measured data and provide experimental confirmation of the technological viability of the ring resonators required by the spectrometer. Full article

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11 pages, 915 KiB

Open AccessCommunication

Thermodynamic Reversibility in Polarimetry

by José J. Gil

Photonics 2022, 9(9), 650; https://doi.org/10.3390/photonics9090650 - 12 Sep 2022

Cited by 1 | Viewed by 995

Abstract

The action of linear media on incident polarized electromagnetic waves can produce two kinds of thermodynamic irreversible effects, namely, loss of intensity, in general anisotropic, and reduction of the degree of polarization. Even though both phenomena can be described through specific properties, the [...] Read more.

The action of linear media on incident polarized electromagnetic waves can produce two kinds of thermodynamic irreversible effects, namely, loss of intensity, in general anisotropic, and reduction of the degree of polarization. Even though both phenomena can be described through specific properties, the overall degree of reversibility of polarimetric interactions can be characterized by means of a single parameter whose minimum and maximum values are achieved by fully irreversible and reversible polarimetric transformations, respectively. Furthermore, the sources of irreversibility associated to the entire family of Mueller matrices proportional to a given one are identified, leading to the definition of the specific reversibility as the square average of the degree of polarimetric purity and the polarimetric dimension index. The feasible values of the degree of reversibility with respect to the mean intensity coefficient and the degree of polarimetric purity are analyzed graphically, and the iso-reversibility branches are identified and analyzed. Furthermore, the behavior of the specific reversibility with respect to the achievable values of the polarimetric dimension index and the degree of polarizance is described by means of the purity figure, and it is compared to the iso-purity elliptical branches in such figure. Full article

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10 pages, 2871 KiB

Open AccessCommunication

Analysis of Display Resolution of Volume Holographic Waveguide and High Resolution by Line-Symmetric Image Input

by Toshiteru Nakamura and Ryushi Fujimura

Photonics 2022, 9(9), 649; https://doi.org/10.3390/photonics9090649 - 12 Sep 2022

Viewed by 1907

Abstract

To reveal the fundamental characteristic of the volume holographic waveguide for a head-mounted display (HMD), we analyzed the resolution of a virtual image. We built a mathematical model considering the off-Bragg diffraction for each ray angle of the signal light ray. The display [...] Read more.

To reveal the fundamental characteristic of the volume holographic waveguide for a head-mounted display (HMD), we analyzed the resolution of a virtual image. We built a mathematical model considering the off-Bragg diffraction for each ray angle of the signal light ray. The display resolution performance of the HMD depended on the thickness of the waveguide and the ray angle. At the lowest-resolution ray angle, the input-point image was broadened more than 0.1° in a viewing angle for a 1-mm-thick waveguide. Conversely, our previously proposed line-symmetric image-input method, in which the input images were symmetrically arranged with respect to the center line, improved the resolution performance and luminance uniformity. We observed that the spread of the point image was suppressed to 0.01°, which was a sufficient resolution for a person with a visual acuity of 0.8. Full article

(This article belongs to the Special Issue Materials, Methods and Models for Holographic Optical Elements)

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14 pages, 4199 KiB

Open AccessArticle

Characterization of Aggregating Agents towards Sensitive Optical Detection of Tryptophan Using Lab-on-a-Chip

by Rekha Gautam, Deepika Chaturvedi, Sanchita Sil, Nikki Kuhar, Saumya Singh and Siva Umapathy

Photonics 2022, 9(9), 648; https://doi.org/10.3390/photonics9090648 - 09 Sep 2022

Cited by 1 | Viewed by 1721

Abstract

The analysis of body fluids is desirable to minimize the invasiveness of diagnostic tests and non-destructive forensic investigations. In this study, surface-enhanced Raman spectroscopy (SERS) is employed for sensitive and reproducible detection of biomolecule focusing on ‘hot spots’ generation and automated flow system. [...] Read more.

The analysis of body fluids is desirable to minimize the invasiveness of diagnostic tests and non-destructive forensic investigations. In this study, surface-enhanced Raman spectroscopy (SERS) is employed for sensitive and reproducible detection of biomolecule focusing on ‘hot spots’ generation and automated flow system. Here, we have demonstrated how the plasmon frequency of nanoparticles can be tuned using different aggregating agents for optimal SERS signals. We have compared the effect of different aggregating agents on silver colloids and the resulting enhancement in Raman signals for Tryptophan which is an important amino acid present as an integral component of various body fluids including blood, saliva, tears, and cerebrospinal fluid. The automated segmented flow system, Lab-on-a-chip (LOC), is employed to trap the analyte in droplets while obtaining reproducible SERS spectra of Tryptophan at μM concentration. Further for a thorough interpretation of enhanced vibrational modes of Tryptophan, a theoretical approach has been applied. By combining both experimental and computational approaches we have identified the most preferable site of Tryptophan for interaction with metal nanoparticles and accurately assigned the enhanced Raman bands. The present study demonstrates that the union of SERS and microfluidics has the potential for spectral fingerprinting of biomolecules present in body fluids with high sensitivity. Full article

(This article belongs to the Special Issue Optical Trapping: Techniques and Applications)

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16 pages, 2766 KiB

Open AccessArticle

Optical Labels Enabled Optical Performance Monitoring in WDM Systems

by Tao Yang, Kaixuan Li, Zhengyu Liu, Xue Wang, Sheping Shi, Liqian Wang and Xue Chen

Photonics 2022, 9(9), 647; https://doi.org/10.3390/photonics9090647 - 09 Sep 2022

Cited by 3 | Viewed by 1574

Abstract

Optical performance monitoring (OPM), particularly the optical power and optical signal-to-noise ratio (OSNR) of each wavelength channel, are of great importance and significance and need to be implemented to ensure stable and efficient operation/maintenance of wavelength division multiplexing (WDM) networks. However, the critical [...] Read more.

Optical performance monitoring (OPM), particularly the optical power and optical signal-to-noise ratio (OSNR) of each wavelength channel, are of great importance and significance and need to be implemented to ensure stable and efficient operation/maintenance of wavelength division multiplexing (WDM) networks. However, the critical monitoring module of existing solutions generally are too expensive, operationally inconvenient and/or functionally limited to apply over WDM systems with numerous nodes. In this paper, a low-cost and high-efficiency OPM scheme based on differential phase shift keying (DPSK)-modulated digital optical labels is proposed and demonstrated. Each pilot tone is modulated by digital surveillance information and treated as an identity indicator and performance predictor that ties up to each wavelength channel and thereby can monitor the performance of all wavelength channels simultaneously by only one low-bandwidth photoelectric detector (PD) and by designed digital signal processing (DSP) algorithms. Simulation results showed that the maximum errors of channel power monitoring and OSNR estimation were both less than 1 dB after 20-span WDM transmission. In addition, offline experiments were also carried out and further verified the feasibility of our OPM scheme. This confirms that the optical label based OPM has lower cost and higher efficiency and thereby is of great potential for mass deployment in practical WDM systems. Full article

(This article belongs to the Special Issue Photonics for Emerging Applications in Communication and Sensing)

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10 pages, 5057 KiB

Open AccessCommunication

Enhancement in Structural and Electroluminescence Properties of Green Light Emission for Semipolar (11–22) InGaN/GaN Based Grown on m-Plane Sapphire via Low Temperature Ammonia Treatment (LTAT)

by Gary Tan, Ahmad Shuhaimi, Rizuan Norhaniza, Norhilmi Zahir, Yan Jie Low, Yew Hoong Wong and Wan Haliza Abd Majid

Photonics 2022, 9(9), 646; https://doi.org/10.3390/photonics9090646 - 08 Sep 2022

Viewed by 1342

Abstract

Research on enhancement green light emitter is important to obtain a perfect red-green-blue (RGB) induced white light source. Unfortunately the present of mixed phase in deposition of InGaN/GaN limited the potential LED efficiency. Therefore, we introduce a new method called as Low Temperature [...] Read more.

Research on enhancement green light emitter is important to obtain a perfect red-green-blue (RGB) induced white light source. Unfortunately the present of mixed phase in deposition of InGaN/GaN limited the potential LED efficiency. Therefore, we introduce a new method called as Low Temperature Ammonia Treatment (LTAT) to eliminate the mixed phase and to enhance the structure properties of InGaN/GaN. Two samples have been prepared, with LTAT (LED A) and without LTAT (LED B). Both samples have been characterized using optical microscope (OM), Atomic Force Microscope (AFM), X-ray rocking curve (XRC) and Electroluminescence (EL). On the structural characterization, the OM results show the present 3D island on LED B sample while sample LED A only shows 2D surface. The RMS surface roughness from AFM are 10.3 ± 0.4 nm and 13.5 ± 10.7 nm for LED A and LED B respectively. XRC analysis proved the LED A with LTAT has a homogenous XRD curve while LED B without LTAT has a mixed phase. The BSFs streak length measured as 1.42 nm⁻¹ and 1.61 nm⁻¹ for LED A and LED B respectively shows low crystallographic defect in LED A compared to LED B. For the EL characteristic, LED A shows a single sharp peak near 538.2 nm wavelength, while LED B shows a broad multi-peak profile at 435.7 nm, 480.6 nm and 520.5 nm. The single sharp peak shows enhancement in green light emission when LTAT is applied during deposition. Successful enhancement is structural and electroluminescence properties shows the effectiveness of LTAT proposed in this work for perfect RGB. Full article

(This article belongs to the Special Issue Advances of Laser Diode and LED)

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Graphical abstract

7 pages, 897 KiB

Open AccessCommunication

Influence of the Width of Launch Beam Distribution on the Transmission Performance of Seven-Core Polymer-Clad Silica Fibers

by Svetislav Savović, Alexandar Djordjevich, Konstantinos Aidinis and Rui Min

Photonics 2022, 9(9), 645; https://doi.org/10.3390/photonics9090645 - 08 Sep 2022

Cited by 2 | Viewed by 1160

Abstract

We propose a space division multiplexing (SDM) in a newly constructed multicore polymer-clad silica fiber (PCSF) with seven cores arrayed in a hexagonal array, each carrying a centrally launched beam. This enables a higher SDM capacity at longer fiber lengths in the proposed [...] Read more.

We propose a space division multiplexing (SDM) in a newly constructed multicore polymer-clad silica fiber (PCSF) with seven cores arrayed in a hexagonal array, each carrying a centrally launched beam. This enables a higher SDM capacity at longer fiber lengths in the proposed seven-core PCSF if compared with previously proposed angular division multiplexing (ADM) in single-core (SC) PCSF. As a result, the SDM is not limited to short fiber lengths in the proposed seven-core PCSF, as it is in the case of the ADM channels due to mode coupling in the SC PCSF. In addition, the time-independent power flow equation (TI PFE) is used to analyze the effect of the width of the launch beam distribution on the equilibrium mode distribution (EMD) and steady state distribution (SSD) in each of the seven cores of the investigated PCSF. The width of the launch beam distribution has a considerable impact on the fiber length at which the EMD and SSD are attained, according to our numerical results. Thus, by decreasing the full width at half maximum (FWHM) of the launch beam distribution from 20 to 2°, the length at which EMD is established increases from L_c = 1020 to 1250 m, and the length at which SSD is attained increases from z_s = 2650 to 3250 m. A narrow launch beam distribution leads to higher bandwidth at small and intermediate fiber lengths. On the other hand, at shorter fiber lengths, a wider launch beam distribution induces a bandwidth change from 1/z proportional to 1/z^1/2 proportional curve, e.g., a slower bandwidth reduction. When building a multicore optical fiber transmission system for SDM, such characterization of multicore PCSFs under various launch conditions should be taken into account. Full article

(This article belongs to the Special Issue Optical Fiber Transmission Systems)

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9 pages, 2702 KiB

Open AccessCommunication

Designation of Pump-Signal Combiner with Negligible Beam Quality Degradation for a 15 kW Tandem-Pumping Fiber Amplifier

by Zhixian Li, Min Fu, Hu Xiao, Zilun Chen, Zefeng Wang and Jinbao Chen

Photonics 2022, 9(9), 644; https://doi.org/10.3390/photonics9090644 - 08 Sep 2022

Cited by 5 | Viewed by 1647

Abstract

In this paper, the fabrication method of a pump/signal (6 + 1) × 1 combiner based on a large-core (48 μm) multimode signal fiber is introduced. Since the signal fiber is not tapered in the production, and an effective feedback alignment method is [...] Read more.

In this paper, the fabrication method of a pump/signal (6 + 1) × 1 combiner based on a large-core (48 μm) multimode signal fiber is introduced. Since the signal fiber is not tapered in the production, and an effective feedback alignment method is adopted during the splice process, the degradation ratio of the M² value of the signal light is only about 5% after passing through the beam combiner. In addition, with the help of a home-made beam combiner, a counter-directional tandem-pumping amplifier is built. The maximum output power of the amplifier is 15.31 kW with the slope efficiency of 83.2%. The temperature rise coefficient of the home-made combiner is 3.2 °C/kW and the backward isolation degree is more than 36 dB from each pump pigtail. Both test results prove the outstanding potential of the pump-signal combiner in high-power laser applications. Full article

(This article belongs to the Section Lasers, Light Sources and Sensors)

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14 pages, 2630 KiB

Open AccessArticle

Goos–Hänchen Lateral Displacements and Angular Deviations: When These Optical Effects Offset Each Other

by Stefano De Leo, Luca Maggio and Moreno d’Ambrosio

Photonics 2022, 9(9), 643; https://doi.org/10.3390/photonics9090643 - 07 Sep 2022

Cited by 2 | Viewed by 1327

Abstract

For optical beams transmitted by a right-angle prism, the Goos–Hänchen shift can never be seen as a pure effect. Indeed, the lateral displacement, caused by the total internal reflection, will always be accompanied by angular deviations generated by the transmission through the incoming [...] Read more.

For optical beams transmitted by a right-angle prism, the Goos–Hänchen shift can never be seen as a pure effect. Indeed, the lateral displacement, caused by the total internal reflection, will always be accompanied by angular deviations generated by the transmission through the incoming and outgoing interfaces. This combined effect can be analyzed by using the Taylor expansion of the Fresnel coefficients. The analytic expression found for the transmitted beam allows us to determine the beam parameters, the incidence angles, and the axial distance for which lateral displacements are compensated by angular deviations. Proposals to optimize experimental implementations are also briefly discussed. Full article

(This article belongs to the Topic Applications of Photonics, Laser, Plasma and Radiation Physics)

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15 pages, 5606 KiB

Open AccessArticle

Single Image Deblurring for Pulsed Laser Range-Gated Imaging System with Multi-Slice Integration

by Hongsheng Lin, Liheng Ma, Qingping Hu, Xiaohui Zhang, Zhang Xiong and Hongwei Han

Photonics 2022, 9(9), 642; https://doi.org/10.3390/photonics9090642 - 07 Sep 2022

Cited by 2 | Viewed by 1627

Abstract

The multi-slice integration (MSI) method is one of the approachs to extend the depth of view (DOV) of the pulsed laser range-gated imaging (PLRGI) system. When the DOV is large enough and exceeds the depth of focus of the system, it may make [...] Read more.

The multi-slice integration (MSI) method is one of the approachs to extend the depth of view (DOV) of the pulsed laser range-gated imaging (PLRGI) system. When the DOV is large enough and exceeds the depth of focus of the system, it may make some targets in the image clear and others blurred. In addition, forward scatter is also considered to have a blurring effect on the image. There is very little literature to solve the combined effect of forward scatter and defocus. An imaging model is built based on the model from Jaffe–McGlamery and Fourier optics. According to the imaging model, backscattered light is independent from reflected light from the target, and forward scatter has a relationship with the reflected light. Thus, backscattered light should be removed before deblurring. First, rolling ball and intensity transformation are used to remove the backscattered light and enhance the image. Then, a deep learning model based on Transformer is used to deblur the image. To enable the deep learning model to accommodate different degrees of blurred image, 16 different blur kernels are generated according to the imaging model. Sharp images from a DPDD dataset were chosen to train the model. Images of varying degrees of blur were collected from a water tank and a boat tank by the PLRGI system as test sets. Image deblurring results show that the proposed method can remove different levels of blur and can deal with images which have sharp targets and blurred targets together. Full article

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10 pages, 3331 KiB

Open AccessCommunication

Dynamics of Nano-Particles Inside an Optical Cavity in the Quantum Regime

by Camilo M. Prada and Luis J. Martínez

Photonics 2022, 9(9), 641; https://doi.org/10.3390/photonics9090641 - 07 Sep 2022

Viewed by 1559

Abstract

We investigate the optomechanical effect on a single nano-particle inside an optical cavity, by deriving the optical forces acting on the nano-particle by the cavity from quantum theory. We obtain the steady state of the system and found that the force contains three [...] Read more.

We investigate the optomechanical effect on a single nano-particle inside an optical cavity, by deriving the optical forces acting on the nano-particle by the cavity from quantum theory. We obtain the steady state of the system and found that the force contains three terms associated with the gradient force, the back-action force resulting from the intra-cavity photon energy change, as well as the reactive force associated with the coupling between the external field and the cavity. Moreover, we solve the dynamical system for a dielectric particle in a small mode volume cavity, which is characterized by a quasi-periodic pattern. These results are important for understanding the control of various types of levitated nano-particles through optomechanical coupling. Full article

(This article belongs to the Special Issue Nonlinear and Quantum Optics in Coupled Structures: Fundamentals and Applications)

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11 pages, 3826 KiB

Open AccessArticle

Camouflage Target Recognition Based on Dimension Reduction Analysis of Hyperspectral Image Regions

by Jiale Zhao, Bing Zhou, Guanglong Wang, Jie Liu and Jiaju Ying

Photonics 2022, 9(9), 640; https://doi.org/10.3390/photonics9090640 - 06 Sep 2022

Cited by 6 | Viewed by 1753

Abstract

Hyperspectral reconnaissance technology can realize three-dimensional reconnaissance by using target space and spectral information, which effectively improves the efficiency of battlefield reconnaissance. However, in order to obscure what is true and what is false to confuse the enemy, camouflage technology is also developing. [...] Read more.

Hyperspectral reconnaissance technology can realize three-dimensional reconnaissance by using target space and spectral information, which effectively improves the efficiency of battlefield reconnaissance. However, in order to obscure what is true and what is false to confuse the enemy, camouflage technology is also developing. Hiding the target in the background environment and setting false targets have become common camouflage procedures on the battlefield. The camouflaged target has very similar spatial and spectral characteristics to the real target, so the method of identifying the camouflaged target according to the similarity threshold of the original spectral data is no longer reliable. In order to solve the problem of high spectral similarity and low discrimination between a camouflaged target and a real target in a hyperspectral image, a joint processing method of spatial spectrum information is adopted in this paper. Firstly, the hyperspectral image is preprocessed, and then the target area to be measured is determined. Finally, the dimensions of the determined sensitive small area are reduced. Experiments show that this processing method can effectively reduce the spectral similarity of true and false targets, increase the spectral difference of true and false targets and improve the ability to identify true and false targets based on hyperspectral images. Full article

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