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Articles de revues sur le sujet « Intensity Modulated -Direct Detection »

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Auteur : Grafiati

Publié le 14 mars 2023

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1

Zhang, Xiaoyu, Thien Van Luong, Periklis Petropoulos et Lajos Hanzo. « Machine-Learning-Aided Optical OFDM for Intensity Modulated Direct Detection ». Journal of Lightwave Technology 40, n^o 8 (15 avril 2022) : 2357–69. http://dx.doi.org/10.1109/jlt.2022.3141222.

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Zhang, Rong, et Lajos Hanzo. « Multi-layer Modulation for Intensity-Modulated Direct-Detection Optical OFDM ». Journal of Optical Communications and Networking 5, n^o 12 (27 novembre 2013) : 1402. http://dx.doi.org/10.1364/jocn.5.001402.

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Alhalabi, Mahmoud, Necmi Taşpınar et Fady I. El-Nahal. « Bidirectional intensity modulated/direct detection optical OFDM WDM-PON system ». Optoelectronics Letters 19, n^o 2 (février 2023) : 83–87. http://dx.doi.org/10.1007/s11801-023-2126-x.

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4

Chen, Gang, Ming Chen, Wen Chen, Lede Yin, Aitao Deng, Yuxin Cai et Dengqiao Wang. « Real-time reception of NHS-OFDM signal with SPA-enhanced channel estimation for intensity-modulated direct-detection systems ». Chinese Optics Letters 20, n^o 5 (2022) : 050601. http://dx.doi.org/10.3788/col202220.050601.

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5

Hranilovic, S., et F. R. Kschischang. « Optical intensity-modulated direct detection channels : signal space and lattice codes ». IEEE Transactions on Information Theory 49, n^o 6 (juin 2003) : 1385–99. http://dx.doi.org/10.1109/tit.2003.811928.

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6

Wang, Qi, Chen Qian, Xuhan Guo, Zhaocheng Wang, David G. Cunningham et Ian H. White. « Layered ACO-OFDM for intensity-modulated direct-detection optical wireless transmission ». Optics Express 23, n^o 9 (1 mai 2015) : 12382. http://dx.doi.org/10.1364/oe.23.012382.

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7

Lee, S. C. J., S. Randel, F. Breyer et A. M. J. Koonen. « PAM-DMT for Intensity-Modulated and Direct-Detection Optical Communication Systems ». IEEE Photonics Technology Letters 21, n^o 23 (décembre 2009) : 1749–51. http://dx.doi.org/10.1109/lpt.2009.2032663.

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8

Bai, Ruowen, Qi Wang et Zhaocheng Wang. « Asymmetrically Clipped Absolute Value Optical OFDM for Intensity-Modulated Direct-Detection Systems ». Journal of Lightwave Technology 35, n^o 17 (1 septembre 2017) : 3680–91. http://dx.doi.org/10.1109/jlt.2017.2716983.

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9

Wang, Zhongpeng, Xiumin Wang, Fangni Chen, Weiwei Qiu et Linpeng Ye. « A Scaling Scheme for DCT Precoded Optical Intensity-Modulated Direct Detection Systems ». Journal of Electrical and Computer Engineering 2015 (2015) : 1–10. http://dx.doi.org/10.1155/2015/367693.

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A scaling technique is employed to improve the performance of a Discrete Cosine Transform (DCT) precoded optical intensity-modulated direct detection (IM/DD) OFDM system, which fully exploits the dynamic range of a digital-to-analog converter (DAC). The theoretical analysis shows that the proposed scaling scheme can improve the BER performance of DCT precoded and scaled OFDM systems. The experiment results also show that the proposed scheme significantly improves the BER performance without changing the receiver structure. The measured received sensitivity at a BER of 10−3for a 4 G samples/s (2.7 Gbits/s) DCT precoded and scaled OFDM signal and after 100 km standard single-mode fiber (SMF) transmission has been improved by 3 and 1.3 dB when compared with the original OFDM system and conventional DCT precoded OFDM system, respectively.

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Bai, Ruowen, Zhaocheng Wang, Rui Jiang et Julian Cheng. « Interleaved DFT-Spread Layered/Enhanced ACO-OFDM for Intensity-Modulated Direct-Detection Systems ». Journal of Lightwave Technology 36, n^o 20 (15 octobre 2018) : 4713–22. http://dx.doi.org/10.1109/jlt.2018.2864275.

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11

Iannone, E., F. Matera, A. Mecozzi et M. Settembre. « Performance evaluation of very long span direct detection intensity and polarization modulated systems ». Journal of Lightwave Technology 14, n^o 3 (mars 1996) : 261–72. http://dx.doi.org/10.1109/50.485583.

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Rademacher, Georg, Ruben S. Luis, Benjamin J. Puttnam, Yoshinari Awaji et Naoya Wada. « Crosstalk-Induced System Outage in Intensity-Modulated Direct-Detection Multi-Core Fiber Transmission ». Journal of Lightwave Technology 38, n^o 2 (15 janvier 2020) : 291–96. http://dx.doi.org/10.1109/jlt.2019.2945654.

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13

Bai, Ruowen, Jiaxuan Chen, Tianqi Mao et Zhaocheng Wang. « Enhanced asymmetrically clipped DC biased optical OFDM for intensity-modulated direct-detection systems ». Journal of Communications and Information Networks 2, n^o 4 (décembre 2017) : 36–46. http://dx.doi.org/10.1007/s41650-017-0035-5.

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Guo, Dong, Wei Zhang, Feng Tian, Jianyang Shi, Kaihui Wang, Miao Kong, Junwen Zhang et al. « LDPC-Coded Generalized Frequency Division Multiplexing for Intensity-Modulated Direct-Detection Optical Systems ». IEEE Photonics Journal 11, n^o 2 (avril 2019) : 1–15. http://dx.doi.org/10.1109/jphot.2019.2902607.

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Vappangi, Suseela, et V. V. Mani. « Performance Analysis of DST-Based Intensity Modulated/Direct Detection (IM/DD) Systems for VLC ». IEEE Sensors Journal 19, n^o 4 (15 février 2019) : 1320–37. http://dx.doi.org/10.1109/jsen.2018.2882378.

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Iannone, E., F. Matera et M. Settembre. « Performance of very long intensity-modulated direct-detection optical links with low chromatic dispersion ». Electronics Letters 30, n^o 7 (31 mars 1994) : 588–89. http://dx.doi.org/10.1049/el:19940385.

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17

Oliari, Vinicius, Caio Santos, Pablo Marciano, Helder Rocha, Marcelo Segatto et Jair Silva. « Closed-Form Expression for BER of CE-OFDM in Optical Intensity-Modulated Direct-Detection Systems ». IEEE Communications Letters 23, n^o 10 (octobre 2019) : 1796–800. http://dx.doi.org/10.1109/lcomm.2019.2929515.

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18

Svaluto Moreolo, Michela, Raul Munoz et Gabriel Junyent. « Novel Power Efficient Optical OFDM Based on Hartley Transform for Intensity-Modulated Direct-Detection Systems ». Journal of Lightwave Technology 28, n^o 5 (mars 2010) : 798–805. http://dx.doi.org/10.1109/jlt.2010.2040580.

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19

Keang-Po Ho. « Exact evaluation of the capacity for intensity-modulated direct-detection channels with optical amplifier noises ». IEEE Photonics Technology Letters 17, n^o 4 (avril 2005) : 858–60. http://dx.doi.org/10.1109/lpt.2005.843947.

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Gong, Xiaoxue, Lei Guo et Yejun Liu. « Power-efficient schemes using directly modulated lasers for intensity modulation and direct detection OFDM-PONs ». Photonic Network Communications 31, n^o 2 (9 août 2015) : 275–84. http://dx.doi.org/10.1007/s11107-015-0544-9.

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21

Stephens, T., K. Hinton, T. Anderson et B. Clarke. « Laser turn-on delay and chirp noise effects in Gb/s intensity-modulated direct-detection systems ». Journal of Lightwave Technology 13, n^o 4 (avril 1995) : 666–74. http://dx.doi.org/10.1109/50.372479.

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Chen, Hongxian, Jing He, Jin Tang, Fan Li, Ming Chen et Lin Chen. « Performance of 16 QAM-OFDM With New Null Subcarrier Shifting in an Intensity-Modulated Direct Detection System ». Journal of Optical Communications and Networking 6, n^o 2 (24 janvier 2014) : 159. http://dx.doi.org/10.1364/jocn.6.000159.

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Petkovic, Milica, Goran Djordjevic, Dejan Milic et Bata Vasic. « BER analysis of IM/DD FSO system with APD receiver over gamma-gamma turbulence ». Serbian Journal of Electrical Engineering 11, n^o 1 (2014) : 61–72. http://dx.doi.org/10.2298/sjee131208006p.

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In this paper, the bit-error rate (BER) performance of intensity modulated with direct detection (IM/DD) free space optical (FSO) system using the on-off keying (OOK) and avalanche photodiode (APD) receiver is analyzed. The intensity fluctuations of the received optical signal are modeled by gamma gamma distribution, while both zero and nonzero inner scale models are observed. The total receiver noise includes APD shot noise and thermal noise. The BER expression is theoretically derived and numerical results are presented. The results illustrate the BER dependence on the turbulence strength, propagation path length, APD gain and noise temperature.

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24

Alsowaidi, Naif, Tawfig Eltaif, Mohd Ridzuan Mokhtar et Belal A. Hamida. « Reduction of Four-Wave Mixing in DWDM System using Electro-Optic Phase Modulator ». International Journal of Electrical and Computer Engineering (IJECE) 8, n^o 4 (1 août 2018) : 2384. http://dx.doi.org/10.11591/ijece.v8i4.pp2384-2389.

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<span>In this paper, electro-optic phase modulator (EOPM) is used to reduce the effect of four-wave mixing (FWM), which is placed after 64 DWDM-channels multiplexer. It was found that the FWM is very sensitive to the phase deviation of the EOPM, and it can be reduced by introducing a phase shift between pulses. The simulation results confirmed the ability of the EOPM in improving the system performanceas indicated by the bit error rates. In term of comparison, the system of 64 channels based intensity modulated/ direct detection (IM/DD) transmission achieved bit error rate of 10<sup>-26</sup> over 30 km and 70km without and with EOPM, respectively.</span>

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25

Lee, Sang Eon, et Jung-Wuk Hong. « Detection of Micro-Cracks in Metals Using Modulation of PZT-Induced Lamb Waves ». Materials 13, n^o 17 (29 août 2020) : 3823. http://dx.doi.org/10.3390/ma13173823.

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The ultrasonic modulation technique, developed by inspecting the nonlinearity from the interactions of crack surfaces, has been considered very effective in detecting fatigue cracks in the early stage of the crack development due to its high sensitivity. The wave modulation is the frequency shift of a wave passing through a crack and does not occur in intact specimens. Various parameters affect the modulation of the wave, but quantitative analysis for each variable has not been comprehensively conducted due to the complicated interaction of irregular crack surfaces. In this study, specimens with a constant crack width are manufactured, and the effects of various excitation parameters on modulated wave generation are analyzed. Based on the analysis, an effective crack detection algorithm is proposed and verified by applying the algorithm to fatigue cracks. For the quantitative analysis, tests are repeatedly conducted by varying parameters. As a result, the excitation intensity shows a strong linear relationship with the amount of modulated waves, and the increase of modulated wave is expected as crack length increases. However, the change in the dynamic characteristics of the specimen with the crack length is more dominant in the results. The excitation frequency is the most dominant variable to generate the modulated waves, but a direct correlation is not observed as it is difficult to measure the interaction of crack surfaces. A numerical analysis technique is developed to accurately simulate the movement and interaction of the crack surface. The crack detection algorithm, improved by using the observations from the quantitative analyses, can distinguish the occurrence of modulated waves from the ambient noises, and the state of the specimens is determined by using two nonlinear indexes.

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Akrami, Y., M. Ashdown, J. Aumont, C. Baccigalupi, M. Ballardini, A. J. Banday, R. B. Barreiro et al. « Planck intermediate results ». Astronomy & ; Astrophysics 644 (décembre 2020) : A100. http://dx.doi.org/10.1051/0004-6361/202038053.

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The largest temperature anisotropy in the cosmic microwave background (CMB) is the dipole, which has been measured with increasing accuracy for more than three decades, particularly with the Planck satellite. The simplest interpretation of the dipole is that it is due to our motion with respect to the rest frame of the CMB. Since current CMB experiments infer temperature anisotropies from angular intensity variations, the dipole modulates the temperature anisotropies with the same frequency dependence as the thermal Sunyaev-Zeldovich (tSZ) effect. We present the first, and significant, detection of this signal in the tSZ maps and find that it is consistent with direct measurements of the CMB dipole, as expected. The signal contributes power in the tSZ maps, which is modulated in a quadrupolar pattern, and we estimate its contribution to the tSZ bispectrum, noting that it contributes negligible noise to the bispectrum at relevant scales.

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27

Wang, Haoyi, Pablo Torres-Ferrera, Valter Ferrero et Roberto Gaudino. « Experimental Study on 25 Gbps C-Band PON over up to 25 km SMF Using a 10G-Class DML + APD IM-DD System ». Photonics 8, n^o 8 (11 août 2021) : 328. http://dx.doi.org/10.3390/photonics8080328.

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In this paper we present an experimental analysis of several modulation formats (pulse amplitude modulation (PAM-2), quaternary pulse amplitude modulation (PAM-4) and electrical duobinary (EDB)) for passive optical network (PON) applications at 25 Gbps bit rate in a C-band 10G-class directly modulated lasers (DML) and avalanche photodiode (APD) intensity modulation and direct detection (IM-DD) system over a single mode fiber (SMF) of up to 25 km, optimizing DML operations and demonstrating that PAM-2 is a promising choice. We also theoretically and experimentally analyzed the channel frequency response of DML and SMF affected by DML chirp and SMF chromatic dispersion.

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Haefner, Joseph W., Christopher T. Middlebrook, Alexander L. Adams, Charles F. Middleton et J. Richard Desalvo. « Tunable microwave photonic transversal filter ». International Journal of Microwave and Wireless Technologies 8, n^o 2 (16 avril 2015) : 205–13. http://dx.doi.org/10.1017/s1759078715000215.

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We present a tapped tunable delay line filter for radiofrequency (RF) photonic filtering applications, capable of rapid tunability over a wide RF bandwidth limited only by the optical components’ losses, while maintaining independence from polarization state. Multiple fiber taps with contrasting dispersion slopes are used in intensity-modulated direct detection microwave photonic links. A temporal delay is generated between the signals within each arm of the link. Once a signal is received using balanced differential detection, nulls are generated as a function of the laser's operating wavelength. Tuning of the laser allows for a rapid shifting of the nulls in the RF spectrum to dynamically mitigate co-site interference. Through this method we demonstrate the potential for rapid tunability over the RF spectrum by the variation of the operating wavelength of the optical carrier.

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Li, Xia, Jelena Vucic, Volker Jungnickel et Jean Armstrong. « On the Capacity of Intensity-Modulated Direct-Detection Systems and the Information Rate of ACO-OFDM for Indoor Optical Wireless Applications ». IEEE Transactions on Communications 60, n^o 3 (mars 2012) : 799–809. http://dx.doi.org/10.1109/tcomm.2012.020612.090300.

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Zhao, Ming, David Nolte, Wonryeon Cho, Fred Regnier, Manoj Varma, Greg Lawrence et John Pasqua. « High-Speed Interferometric Detection of Label-Free Immunoassays on the Biological Compact Disc ». Clinical Chemistry 52, n^o 11 (1 novembre 2006) : 2135–40. http://dx.doi.org/10.1373/clinchem.2006.072793.

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Abstract Background: We describe a direct-detection immunoassay that uses high-speed optical interferometry on a biological compact disc (BioCD). Methods: We fabricated phase-contrast BioCDs from 100-mm diameter 1.1-mm thick borosilicate glass disks coated with a 10-layer dielectric stack of Ta2O5/SiO2 that serves as a mirror with a center wavelength at 635 nm. The final layer is a λ/4 layer of SiO2 onto which protein patterns are immobilized through several different chemical approaches. Protein on the disc is scanned by a focused laser spot as the disc spins. Interaction of the light with the protein provides both a phase-modulated signal and a local reference that are combined interferometrically to convert phase into intensity. A periodic pattern of protein on the spinning disc produces an intensity modulation as a function of time that is proportional to the surface-bound mass. The binding of antigen or antibodies is detected directly, without labels, by a change in the interferometric intensity. The technique is demonstrated with a reverse assay of immobilized rabbit and mouse IgG antigen incubated against anti-IgG antibody in a casein buffer. Results: The signal increased with increased concentration of analyte. The current embodiment detected a concentration of 100 ng/L when averaged over ∼3000 100-micron-diameter protein spots. Conclusions: High-speed interferometric detection of label-free protein assays on a rapidly spinning BioCD is a high-sensitivity approach that is amenable to scaling up to many analytes.

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Jin, Shilei, Longtao Xu, Tariq Manzur et Yifei Li. « Quantum Well Mach–Zehnder Intensity Modulator With Enhanced Linearity for Direct Detection RF Photonic Link ». Journal of Lightwave Technology 35, n^o 17 (1 septembre 2017) : 3785–90. http://dx.doi.org/10.1109/jlt.2017.2717904.

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FALL, Papa Alioune, et Mangone Fall. « Experimental Investigation of Intensity Modulator/Direct Detection (IM/DD) Optical OFDM System with Fiber Bragg Grating (FBG) ». Journal of Optical Communications 41, n^o 3 (28 avril 2020) : 257–62. http://dx.doi.org/10.1515/joc-2017-0192.

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AbstractTo improve the performance of optical fiber transmission and to compensate the fiber chromatic dispersion (CD), we propose to use fiber Bragg grating (FBG) in intensity modulator/direct detection IM/DD optical orthogonal frequency division multiplexing (OOFDM) system, and experimentally demonstrate 2.5-Gbit/s QPSK-OFDM transmission over 200 km SMF-28. FBG used before the detection as a chromatic dispersion compensation module, reducing the beating noise between ASE noise and OFDM signal. By using the FBG in IM/DD OOFDM system, our experimental results show that the receiver sensitivity was improved about 2 dB at a bit error rate (BER) of $1 \times {10^{ - 3}}$ for 2.5 Gbit/s QPSK-OFDM signals after 200 km SMF-transmission compared to regular system without FBG.

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Zheng, X., C. Sánchez, B. Ortega et J. M. Tang. « Compensation of directly modulated distributed feedback laser frequency chirps in optical orthogonal frequency division multiplexing intensity-modulation and direct-detection passive optical network systems ». IET Optoelectronics 6, n^o 2 (2012) : 75. http://dx.doi.org/10.1049/iet-opt.2011.0050.

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Hassan, MD Zoheb, Tanveer Ahmed Bhuiyan, S. M. Shahrear Tanzil et S. P. Majumder. « Turbo-Coded MC-CDMA Communication Link over Strong Turbulence Fading Limited FSO Channel with Receiver Space Diversity ». ISRN Communications and Networking 2011 (22 août 2011) : 1–14. http://dx.doi.org/10.5402/2011/701670.

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This paper demonstrates an analytical approach on the bit error rate (BER) performance evaluation of a multi- carrier code division multiple access (MC-CDMA) communication link operating over terrestrial free space optical (FSO) channel considering effect of atmospheric turbulence The turbulence induced intensity fading is statistically modeled by Gamma-Gamma PDF (probability density function). Bit error rate performance improvement is proposed using photo detector spatial diversity with Equal Gain Combining (EGC) and Turbo Coding. Analysis is carried out with different bandwidth efficient phase shift keying (PSK) based sub-carrier intensity modulation (SIM) with direct detection. Numerical simulation results of proposed analytical model indicate that, sub-carrier intensity modulation scheme; number of receiver photo detectors, turbo coding parameter and link length should be optimally engineered for ensuring system reliability. It can be inferred from the simulation that, a reliable communication link ( BER) can be established over a link length of 4 Km in strong turbulence fading condition using an array of 4 PIN photo detectors, 8-ary PSK based sub-carrier intensity modulation scheme and appropriate turbo coding parameter with an average 10.2 dB CINR (Carrier to Interference and Noise Ratio) requirement per photo detector. Besides, more than 130 dB average CINR gain is also confirmed from BPSK modulated, un-coded SISO (single input-single output) system for maintaining targeted BER () in presence of strong turbulence fading.

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Kim, Gunzung, et Yongwan Park. « Independent Biaxial Scanning Light Detection and Ranging System Based on Coded Laser Pulses without Idle Listening Time ». Sensors 18, n^o 9 (4 septembre 2018) : 2943. http://dx.doi.org/10.3390/s18092943.

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The goal of light detection and ranging (LIDAR) systems is to achieve high-resolution three-dimensional distance images with high refresh rates and long distances. In scanning LIDAR systems, an idle listening time between pulse transmission and reception is a significant obstacle to accomplishing this goal. We apply intensity-modulated direct detection (IM/DD) optical code division multiple access (OCDMA) using nonreturn-to-zero on-off keying to eliminate the idle listening time in scanning LIDAR systems. The transmitter records time information while emitting a coded laser pulse in the measurement angle derived from the pixel information as the measurement direction. The receiver extracts and decodes the reflected laser pulses and estimates the distance to the target using time-of-flight until the pulse is received after being transmitted. Also, we rely on a series of pulses and eliminate alien pulses via several detection decision steps to enhance the robustness of the decision result. We built a prototype system and evaluated its performance by measuring black matte and white paper walls and assessing object detection by measuring a watering can in front of the black matte paper wall. This LIDAR system eliminated both shot and background noises in the reception process and measured greater distances with improvements in accuracy and precision.

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Lange, Sophie, Stefan Wolf, Joachim Lutz, Lars Altenhain, Rolf Schmid, Ronald Kaiser, Martin Schell, Christian Koos et Sebastian Randel. « 100 GBd Intensity Modulation and Direct Detection With an InP-Based Monolithic DFB Laser Mach–Zehnder Modulator ». Journal of Lightwave Technology 36, n^o 1 (1 janvier 2018) : 97–102. http://dx.doi.org/10.1109/jlt.2017.2743211.

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Julus, L. Jerart, D. Manimegalai et S. Sibi Chakkaravarthy. « FBMC-based dispersion compensation using artificial neural network equalization for long reach-passive optical network ». International Journal of Wavelets, Multiresolution and Information Processing 18, n^o 01 (9 avril 2019) : 1941011. http://dx.doi.org/10.1142/s021969131941011x.

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This paper presents a Filter Bank Multicarrier (FBMC), a viable waveform candidate for fifth generation (5G) communications using Staggered-Modulated Multitone (SMT). FBMC is preferred in optical communication because of its ability to work without Cyclic Prefix (CP). In any case, the operation of FBMC in optical access systems with Artificial Neural Networks (ANNs) has not been broadly explored either downstream or upstream. This work presents an advanced Nonlinear Feed-Forward Equalizer (NFFE) that makes use of multilayer ANN for dispersion compensation. ANN is trained to act as a filter with an extensive equalizer training which has the ability to mitigate dispersion and increase the performance of the system. The simulation work is used to study the performance of intensity modulated FBMC system with direct detection in Long Reach-Passive Optical Networks (LR-PONs).The transmission data rate is varied between 8 and 10[Formula: see text]Gbps with the optical fiber length from 30 to 90[Formula: see text]km of Standard Single Mode Fiber (SSMF). The obtained result suggests that FBMC system with ANN-NFFE equalizer fundamentally builds the resilience to the Chromatic Dispersion (CD) distortion, and a CP-less transmission is possible upto 90[Formula: see text]km.

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Zhang, Xu, Yu Fang Zhou, Yin Peng Yu, Peng Chao Han et Xiao Rui Wang. « Comparison and Analysis of DCO-OFDM, ACO-OFDM and ADO-OFDM in IM/DD Systems ». Applied Mechanics and Materials 701-702 (décembre 2014) : 1059–62. http://dx.doi.org/10.4028/www.scientific.net/amm.701-702.1059.

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As a promising modulation technology for optical communication, Orthogonal Frequency Division Multiplexing (OFDM) is now increasingly used and a lot of ways of improving the optical efficiency of Intensity Modulated/ Direct Detection (IM/DD) systems have been proposed. And real and non-negative OFDM signals are required in this kind of system. Asymmetrically clipped DC biased Optical OFDM (DCO-OFDM), Asymmetrically Clipped Optical OFDM (ACO-OFDM) and Asymmetrically clipped DC biased Optical OFDM (ADO-OFDM) can satisfy this requirement. In this paper, we analysis the properties and performance orderly of the above three systems and simultaneously compare their performance. The simulation results show that DCO-OFDM is efficient in terms of bandwidth while the ACO-OFDM is efficient in terms of optical power. More importantly, ADO-OFDM is both power-efficient and bandwidth-efficient. At the same time, a developmentally proposal for the future OFDM in IM/DD systems is put forward.

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Khair, Fauza, Fakhriy Hario P, I. Wayan Mustika et Budi Setiyanto. « Performance Analysis of Digital Modulation for Coherent Detection of OFDM Scheme on Radio over Fiber System ». International Journal of Electrical and Computer Engineering (IJECE) 6, n^o 3 (1 juin 2016) : 1086. http://dx.doi.org/10.11591/ijece.v6i3.9656.

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Radio over fiber (RoF) system with the coherent detection offers high linearity for the transparent transport of high-frequency microwave signals, and better receiver sensitivity compared with intensity-modulated direct detection systems. The purpose of this paper is to analyze the performance of digital modulation for coherent detection of orthogonal frequency division multiplexing (OFDM) scheme on RoF system at 10 Gbps up to 100 km fiber length. The results show that coherent detection of OFDM-RoF system with 16 quadrature amplitude modulation (16-QAM) has the value of bit error rate (BER) and the symbol error rate (SER) is very low and its constellation is better compared with other modulation formats (4-QAM, quadrature phase shift keying (QPSK), 8-PSK and 16-PSK), which BER 16-QAM is 0.053 and SER is 15.7%. The results also show that BER value of 4-QAM and QPSK relatively similar to fiber length variations. In general, an increasing value of the BER and SER for each modulation format are almost equal to the fiber length of 60-70 km (Region I and II). However, there is a significant increase in the value of BER in fiber length of 80-100 km (Region III. A and III. B) for the modulation of 4-QAM, QPSK, 8-PSK, and 16-PSK.

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Khair, Fauza, Fakhriy Hario P, I. Wayan Mustika et Budi Setiyanto. « Performance Analysis of Digital Modulation for Coherent Detection of OFDM Scheme on Radio over Fiber System ». International Journal of Electrical and Computer Engineering (IJECE) 6, n^o 3 (1 juin 2016) : 1086. http://dx.doi.org/10.11591/ijece.v6i3.pp1086-1095.

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Radio over fiber (RoF) system with the coherent detection offers high linearity for the transparent transport of high-frequency microwave signals, and better receiver sensitivity compared with intensity-modulated direct detection systems. The purpose of this paper is to analyze the performance of digital modulation for coherent detection of orthogonal frequency division multiplexing (OFDM) scheme on RoF system at 10 Gbps up to 100 km fiber length. The results show that coherent detection of OFDM-RoF system with 16 quadrature amplitude modulation (16-QAM) has the value of bit error rate (BER) and the symbol error rate (SER) is very low and its constellation is better compared with other modulation formats (4-QAM, quadrature phase shift keying (QPSK), 8-PSK and 16-PSK), which BER 16-QAM is 0.053 and SER is 15.7%. The results also show that BER value of 4-QAM and QPSK relatively similar to fiber length variations. In general, an increasing value of the BER and SER for each modulation format are almost equal to the fiber length of 60-70 km (Region I and II). However, there is a significant increase in the value of BER in fiber length of 80-100 km (Region III. A and III. B) for the modulation of 4-QAM, QPSK, 8-PSK, and 16-PSK.

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Lowery, Arthur James. « Spectrally efficient optical orthogonal frequency division multiplexing ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 378, n^o 2169 (2 mars 2020) : 20190180. http://dx.doi.org/10.1098/rsta.2019.0180.

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This paper charts the development of spectrally efficient forms of optical orthogonal frequency division multiplexing (OFDM) that are suited for intensity-modulated direct detection systems, such as wireless optical communications. The journey begins with systems using a DC-bias to ensure that no parts of the signal that modulates the optical source are negative in value, as negative optical intensity is unphysical. As the DC-part of the optical signal carries no information, it is wasteful in energy; thus asymmetrically clipped optical OFDM was developed, removing any negative-going peaks below the mean. Unfortunately, the clipping causes second-order distortion and intermodulation, so some subcarriers appear to be unusable, halving spectral efficiency; this is similar for unipolar and flipped optical OFDM. Thus, a considerable effort has been made to regain spectral efficiency, using layered techniques where the clipping distortion is mostly cancelled at the receiver, from a knowledge of one unpolluted layer, enabling one or more extra ‘layers/paths/depths’ to be received on the previously unusable subcarriers. Importantly, for a given optical power and high-order modulation, layered methods offer the best spectral efficiencies and need the lowest signal-to-noise ratios, especially if diversity combining is used. Thus, they could be important for high-bandwidth optical fibre systems. Efficient methods of generating all layers simultaneously, using fast Fourier transforms with their partial calculations extracted, are discussed, as are experimental demonstrations in both wireless and short-haul communications links. A musical analogy is also provided, which may point to how orchestral and rock music is deciphered in the brain. This article is part of the theme issue ‘Optical wireless communication’.

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Zhu, Yixiao, Xin Miao, Qi Wu, Longjie Yin et Weisheng Hu. « Imbalanced Mach-Zehnder Modulator for Fading Suppression in Dispersion-Uncompensated Direct Detection System ». Electronics 10, n^o 22 (21 novembre 2021) : 2866. http://dx.doi.org/10.3390/electronics10222866.

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In this work, we systematically analyze the impact of three kinds of Mach-Zehnder modulator (MZM) imbalances, including bias deviation, amplitude mismatch, and differential time skew in intensity-modulation direct-detection (IM-DD) links. It is shown that, for power fading limited transmission, the imbalances can be utilized as advantages rather than impairments. Specifically, the bias deviation with single-arm driven mode and amplitude mismatch with differential driven mode can increase the available bandwidth by shifting the frequency of fading notches. Meanwhile, time skew provides another way to avoid fading by shaping the double sideband (DSB) signal into a vestigial sideband (VSB) with an asymmetrical transfer function. In the transmission experiment, 34 Gbaud Nyquist 6/8-ary pulse amplitude modulation (PAM-6/8) signals are used for investigation in a 20 km dispersion-uncompensated standard single-mode fiber (SSMF) link. With the help of a Volterra nonlinear equalizer, all three kinds of imbalances can achieve bit-error rates (BERs) below the 7% and 20% hard-decision forward error correction (HD-FEC) thresholds for PAM-6 and PAM-8 signals, respectively. The received power sensitivity is also compared at the back-to-back (BTB) case and after fiber transmission. Both numerical simulation and experimental demonstration confirm that the dispersion-induced power fading can be effectively suppressed with bias, amplitude, or skew imbalance, providing a feasible solution for transmission distance extension of C-band DD links.

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Morsy-Osman, Mohamed, Mathieu Chagnon, Michel Poulin, Stephane Lessard et David V. Plant. « 224-Gb/s 10-km Transmission of PDM PAM-4 at 1.3 μm Using a Single Intensity-Modulated Laser and a Direct-Detection MIMO DSP-Based Receiver ». Journal of Lightwave Technology 33, n^o 7 (1 avril 2015) : 1417–24. http://dx.doi.org/10.1109/jlt.2015.2390650.

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Bendahan, J., W. G. J. Langeveld, V. Bharadwaj, J. Amann, C. Limborg et Y. Nosochkov. « Vertical intensity modulation for improved radiographic penetration and reduced exclusion zone ». International Journal of Modern Physics : Conference Series 44 (janvier 2016) : 1660213. http://dx.doi.org/10.1142/s2010194516602131.

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In the present work, a method to direct the X-ray beam in real time to the desired locations in the cargo to increase penetration and reduce exclusion zone is presented. Cargo scanners employ high energy X-rays to produce radiographic images of the cargo. Most new scanners employ dual-energy to produce, in addition to attenuation maps, atomic number information in order to facilitate the detection of contraband. The electron beam producing the bremsstrahlung X-ray beam is usually directed approximately to the center of the container, concentrating the highest X-ray intensity to that area. Other parts of the container are exposed to lower radiation levels due to the large drop-off of the bremsstrahlung radiation intensity as a function of angle, especially for high energies (>6 MV). This results in lower penetration in these areas, requiring higher power sources that increase the dose and exclusion zone. The capability to modulate the X-ray source intensity on a pulse-by-pulse basis to deliver only as much radiation as required to the cargo has been reported previously. This method is, however, controlled by the most attenuating part of the inspected slice, resulting in excessive radiation to other areas of the cargo. A method to direct a dual-energy beam has been developed to provide a more precisely controlled level of required radiation to highly attenuating areas. The present method is based on steering the dual-energy electron beam using magnetic components on a pulse-to-pulse basis to a fixed location on the X-ray production target, but incident at different angles so as to direct the maximum intensity of the produced bremsstrahlung to the desired locations. The details of the technique and subsystem and simulation results are presented.

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El-Fiky, Eslam, Mohamed Osman, Mohammed Sowailem, Alireza Samani, David Patel, Rui Li, Md G. Saber et al. « 200 Gb/s transmission using a dual-polarization O-Band silicon photonic intensity modulator for Stokes vector direct detection applications ». Optics Express 25, n^o 24 (17 novembre 2017) : 30336. http://dx.doi.org/10.1364/oe.25.030336.

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Avendaño-Lopez, Carlos M., Rogelio Castro-Sanchez, Dora L. Almanza-Ojeda, Juan Gabriel Avina-Cervantes, Miguel A. Gomez-Martinez et Mario A. Ibarra-Manzano. « Scalable Visible Light Indoor Positioning System Using RSS ». Mathematics 10, n^o 10 (19 mai 2022) : 1738. http://dx.doi.org/10.3390/math10101738.

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This paper proposes a visible light positioning system that utilizes commercial Light-Emitting Diode (LED) lamps as transmitters and Silicon PIN photodiodes as receivers. The light signals are transmitted and received using Intensity Modulation and Direct Detection (IMDD). The lamps are modulated using On–Off Keying (OOK) with the Manchester code, and the medium access control is achieved by Time-Division Multiplexing (TDM). The position is estimated using trilateration based on the Received Signal Strength (RSS). The system’s scalability is accomplished by replicating primary localization cells composed of seven lamps and drawing on the neighborhood synchrony, exploiting the spatial multiplexing property of the light. A basic unit in the cell comprises three lamps forming a localization triangle; then, one primary localization cell shall consist of six triangles sharing lights among basic neighbor units. The cell prototype was implemented to prove the working principle of the system. Three estimation methods were used to compute the position: a deterministic approach based on least-squares regression, an Artificial Neural Network (ANN) per lamp, and an ANN for the complete system. The best per lamp estimator was the ANN, computing positions that reached an experimental accuracy of 2.5 cm under indoor conditions.

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Zakrzewski, Zbigniew. « Optical Channel Selection Avoiding DIPP in DSB-RFoF Fronthaul Interface ». Entropy 23, n^o 11 (22 novembre 2021) : 1554. http://dx.doi.org/10.3390/e23111554.

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The paper presents a method of selecting an optical channel for transporting the double-sideband radio-frequency-over-fiber (DSB-RFoF) radio signal over the optical fronthaul path, avoiding the dispersion-induced power penalty (DIPP) phenomenon. The presented method complements the possibilities of a short-range optical network working in the flexible dense wavelength division multiplexing (DWDM) format, where chromatic dispersion compensation is not applied. As part of the study, calculations were made that indicate the limitations of the proposed method and allow for the development of an algorithm for effective optical channel selection in the presence of the DIPP phenomenon experienced in the optical link working in the intensity modulation–direct detection (IM-DD) technique. Calculations were made for three types of single-mode optical fibers and for selected microwave radio carriers that are used in current systems or will be used in next-generation wireless communication systems. In order to verify the calculations and theoretical considerations, a computer simulation was performed for two types of optical fibers and for two selected radio carriers. In the modulated radio signal, the cyclic-prefix orthogonal frequency division multiplexing (CP-OFDM) format and the 5G numerology were used.

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Yu, Jiawei, Qing Li, Hongwei Li, Qiang Wang, Guozhong Zhou, Dong He, Shaoxiong Xu, Yunxia Xia et Yongmei Huang. « High-Precision Light Spot Position Detection in Low SNR Condition Based on Quadrant Detector ». Applied Sciences 9, n^o 7 (28 mars 2019) : 1299. http://dx.doi.org/10.3390/app9071299.

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In free space optical communications, long-distance transmission leads to the attenuation of beacon light, where we adopt a quadrant detector (QD) to receive the weak signal. However, the background light interferes so strongly that the output signal-to-noise ratio (SNR) of QD is at a low level, which causes a decrease in accuracy of the direct detection method. This requires finding a new light spot detection method, so an improved detection method is proposed. Because the dark current noise and the background light noise are both white noise, we adopt a Kalman filter to estimate the real output of four electric signals of QD. Unfortunately, running these through an amplifier introduces some direct current (DC) offsets into the signals. In order to balance the effect of the DC offsets, we consider using the modulation method, where we employ a sine signal to modulate the intensity of the beacon light at the transmitting end, after which we can give an inverse gain to move the center of signals to near zero to eliminate the DC offsets when we calculate the data. In Kalman filtering, we use the peak values of the signals in every period after the analog to digital converter (ADC) as the elements of the measurement matrix. Experimental results show that even when QD output SNR is about −10 dB, the detection root-mean-square errors decrease by 51.5% using the improved detection method compared with the direct detection method. Moreover, Kalman filtering does not require a large amount of data, which means it works efficiently, can reduce the cost of hardware resources, and is available for the real-time calculation of spot position.

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Li, Qing, Shaoxiong Xu, Jiawei Yu, Lingjie Yan et Yongmei Huang. « An Improved Method for the Position Detection of a Quadrant Detector for Free Space Optical Communication ». Sensors 19, n^o 1 (5 janvier 2019) : 175. http://dx.doi.org/10.3390/s19010175.

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In free space optical communication, a beacon light loses too much energy after a long-distance transmission and faces strong interference from background light. The beacon light illuminated on a quadrant detector (QD) is so weak that the output signal-to-noise ratio (SNR) of a QD is very low, which leads to a significant decrease in the accuracy of the direct position detection method. To solve this problem, an improved light spot position detecting method is proposed. Since the background light and the dark current noise are white noise, we could consider concentrating the energy of QD output signal at a certain frequency point to enhance the output SNR. Therefore, a cosine signal is used to modulate the intensity of a beacon light at the transmitting end. Then the QD output photocurrents are also cosine signals with the same frequency as the modulating signal. Putting the photocurrent signals into a cross-correlation operation with a reference signal, which is the same as the modulating signal, can enhance the QD output SNR at a certain frequency point. Unfortunately, the result of the classical cross-correlation is attenuated with increasing delay. It is hard to detect the amplitude of the classical cross-correlation result. So, we used cyclic cross-correlation to obtain a stable correlation result to detect its amplitude accurately. The experiment results show that even when the QD output SNR is less than −17 dB, the detection root-mean-square error of the proposed method is 0.0092 mm, which is a quarter of the direct position detection method. Moreover, this method only needs a small amount of data to accomplish the calculation and is especially suitable for real-time spot position detection.

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Quagliarini, Erica, Luca Digiacomo, Damiano Caputo, Alessandro Coppola, Heinz Amenitsch, Giulio Caracciolo et Daniela Pozzi. « Magnetic Levitation of Personalized Nanoparticle–Protein Corona as an Effective Tool for Cancer Detection ». Nanomaterials 12, n^o 9 (19 avril 2022) : 1397. http://dx.doi.org/10.3390/nano12091397.

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Unprecedented opportunities for early stage cancer detection have recently emerged from the characterization of the personalized protein corona (PC), i.e., the protein cloud that surrounds nanoparticles (NPs) upon exposure to a patients’ bodily fluids. Most of these methods require “direct characterization” of the PC., i.e., they necessitate protein isolation, identification, and quantification. Each of these steps can introduce bias and affect reproducibility and inter-laboratory consistency of experimental data. To fulfill this gap, here we develop a nanoparticle-enabled blood (NEB) test based on the indirect characterization of the personalized PC by magnetic levitation (MagLev). The MagLev NEB test works by analyzing the levitation profiles of PC-coated graphene oxide (GO) NPs that migrate along a magnetic field gradient in a paramagnetic medium. For the test validation, we employed human plasma samples from 15 healthy individuals and 30 oncological patients affected by four cancer types, namely breast cancer, prostate cancer, colorectal cancer, and pancreatic ductal adenocarcinoma (PDAC). Over the last 15 years prostate cancer, colorectal cancer, and PDAC have continuously been the second, third, and fourth leading sites of cancer-related deaths in men, while breast cancer, colorectal cancer, and PDAC are the second, third and fourth leading sites for women. This proof-of-concept investigation shows that the sensitivity and specificity of the MagLev NEB test depend on the cancer type, with the global classification accuracy ranging from 70% for prostate cancer to an impressive 93.3% for PDAC. We also discuss how this tool could benefit from several tunable parameters (e.g., the intensity of magnetic field gradient, NP type, exposure conditions, etc.) that can be modulated to optimize the detection of different cancer types with high sensitivity and specificity.

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