2020
2020
-
Record 109 of
Title:Toroidal dipole bound states in the continuum metasurfaces for terahertz nanofilm sensing
Author(s):Chen, Xu(1); Fan, Wenhui(1,2,3); Yan, Hui(1,2)Source: Optics Express Volume: 28 Issue: 11 DOI: 10.1364/OE.394416 Published: May 25, 2020Abstract:A novel terahertz nanofilm sensor consisting of toroidal dipole bound states in the continuum (TD-BIC) inspired Fano resonance metasurface is proposed and investigated, which exhibits both the TD character and BIC feature. When the mirror symmetry of the unit cell was broken, the TD resonance was excited and demonstrated by anti-aligned magnetic dipoles and calculated scattering powers and the BIC mode was verified with the quality factor satisfying the inverse square law. Combined with the amplitude difference referencing technique, the TD-BIC inspired Fano resonance was utilized for nanofilm sensing at THz frequencies for the first time. Simulation results show that the amplitude difference can be easily observed by comparing the resonance frequency shift under difference thicknesses of germanium overlayer. Moreover, by coating with a 40 nm-thick analyte overlayer, the sensitivity of amplitude difference can achieve 0.32/RIU, which is a significant value and more suitable for sensing nanofilm analytes than the traditional frequency shift method. These advantages make our proposed structure have potential applications in sensing nanofilm analytes. ? 2020 Optical Society of America under the terms of the OSA Open Access Publishing AgreementAccession Number: 20202208764233 -
Record 110 of
Title:Experimental Investigation of Fiber Scrambling
Author(s):Ye, Huiqi(1,2); Huang, Kai(3); Xiao, Dong(1,2); Zhang, Kai(1,2); Chen, Ping(3); Wei, Ruyi(4)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 40 Issue: 6 DOI: 10.3788/AOS202040.0606001 Published: March 25, 2020Abstract:Radial velocity measurements errors caused by lighting instabilities severely limit the precision improvement in instruments; however, fiber scrambling is an effective method to enhance the stability of instrumental illumination. To provide a reliable experimental reference for the operation of a high resolution spectrograph upgrade and a new high precision radial velocity instrument design, the near field and far field scrambling properties of a single circular fiber, single octagonal fiber, circular-octagonal-circular fiber cascade connection system, double circular fiber scrambler, circular-octagonal hybrid double-fiber scrambler, and double octagonal fiber scrambler were studied in detail. The results showed that the octagonal fiber improved the near field scrambling compared to single circular fiber, the double-fiber scrambler could improve both near field and far field scrambling, and the double octagonal fiber scrambler optimally performed for both near field and far field. Furthermore, the prototypes of the double-fiber scramblers, including ball lens system and twin lens system, were also assessed herein. The throughput was observed to be 55% and 80%, respectively. ? 2020, Chinese Lasers Press. All right reserved.Accession Number: 20202208761655 -
Record 111 of
Title:Photonic RF Phase-Encoded Signal Generation with a Microcomb Source
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiang(1); Boes, Andreas(2); Corcoran, Bill(3); Nguyen, Thach G.(2); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6); Mitchell, Arnan(2); Moss, David(1)Source: Journal of Lightwave Technology Volume: 38 Issue: 7 DOI: 10.1109/JLT.2019.2958564 Published: April 1, 2020Abstract:We demonstrate photonic RF phase encoding based on an integrated micro-comb source. By assembling single-cycle Gaussian pulse replicas using a transversal filtering structure, phase encoded waveforms can be generated by programming the weights of the wavelength channels. This approach eliminates the need for RF signal generators for RF carrier generation or arbitrary waveform generators for phase encoded signal generation. A large number of wavelengths - up to 60 - were provided by the microcomb source, yielding a high pulse compression ratio of 30. Reconfigurable phase encoding rates ranging from 2 to 6 Gb/s were achieved by adjusting the length of each phase code. This article demonstrates the significant potentials of this microcomb-based approach to achieve high-speed RF photonic phase encoding with low cost and footprint. ? 1983-2012 IEEE.Accession Number: 20201608476816 -
Record 112 of
Title:Classification of skin cancer based on fluorescence lifetime imaging and machine learning
Author(s):Yang, Qianqian(1); Qi, Meijie(1); Wu, Zhaoqing(1); Liu, Lixin(1,2,3); Gao, Peng(1); Qu, Junle(4)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 11553 Issue: DOI: 10.1117/12.2573851 Published: 2020Abstract:To evaluate the development stage of skin cancer accurately is very important for prompt treatment and clinical prognosis. In this paper, we used the FLIM system based on time-correlated single-photon counting (TCSPC) to acquire fluorescence lifetime images of skin tissues. In the cases of full sample data, three kinds of sample set partitioning methods, including bootstrapping method, hold-out method and K-fold cross-validation method, were used to divide the samples into calibration set and prediction set, respectively. Then the binary classification models for skin cancer were established based on random forest (RF), K-nearest neighbor (KNN),support vector machine (SVM) and linear discriminant analysis (LDA) respectively. The results showed that FLIM combining with appropriate machine learning algorithms can achieve early and advanced canceration classification of skin cancer, which could provide reference for the multi-classification, clinical staging and diagnosis of skin cancer. ? 2020 SPIE. All rights reserved.Accession Number: 20204909588079 -
Record 113 of
Title:A photonic microwave and RF integrator based on a transversal filter
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(1); Boes, Andreas(2); Corcoran, Bill(3); Nguyen, Thach G.(2); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6); Mitchell, Arnan(2); Moss, David J.(1)Source: TechRxiv Volume: Issue: DOI: 10.36227/techrxiv.11888217 Published: February 23, 2020Abstract:We demonstrate a photonic RF integrator based on an integrated soliton crystal micro-comb source. By multicasting and progressively delaying the input RF signal using a transversal structure, the input RF signal is integrated discretely. Up to 81 wavelengths are provided by the microcomb source, which enable a large integration time window of ~6.8 ns, together with a time resolution as fast as ~84 ps. We perform signal integration of a diverse range of input RF signals including Gaussian pulses with varying time widths, dual pulses with varying time intervals and a square waveform. The experimental results show good agreement with theory. These results verify our microcomb-based integrator as a competitive approach for RF signal integration with high performance and potentially lower cost and footprint. ? 2020, CC BY.Accession Number: 20220138643 -
Record 114 of
Title:Effect of annealing on the electrophysical properties of CdTe/HgCdTe passivation interface by the capacitance-voltage characteristics of the metal-insulator-semiconductor structures
Author(s):Wang, Xi(1); He, Kai(2); Chen, Xing(1); Li, Yang(3); Lin, Chun(1); Zhang, Qinyao(1); Ye, Zhenhua(1); Xin, Liwei(2); Gao, Guilong(2); Yan, Xin(2); Wang, Gang(2,4); Liu, Yiheng(2,4); Wang, Tao(2); Tian, Jinshou(2)Source: AIP Advances Volume: 10 Issue: 10 DOI: 10.1063/5.0021073 Published: October 1, 2020Abstract:The capacitance-voltage characteristics of metal-insulator-semiconductor structures based on Hg1-xCdxTe (x = 0.218) with CdTe passivation are studied before and after the passivation annealing process. We found that after vacuum annealing at 300 °C for 24 h, the micromorphology of the passivation layer was significantly improved, and as the fixed charge density decreased from 1.3 × 1012 cm-2 to 1.0 × 1010 cm-2, the fast surface state density decreased from 2 × 1013 cm-2 eV-1 to 3 × 1012 cm-2 eV-1, with a minimum value of 1.2 × 1011 cm-2 eV-1. From these findings, combined with the secondary ion mass spectroscopy analysis, we conclude that the annealing process propagates an equivalent electrical surface for CdTe/HgCdTe uniformly from the principal physical interface to the inside of the bulk material, effectively improving the characteristics of the CdTe passivation layer. ? 2020 Author(s).Accession Number: 20204409407346 -
Record 115 of
Title:New Algorithm of Response Curve for Fitting HDR Image
Author(s):Qiu, Shi(1); Li, Xuemei(2); Huang, Yongdong(3); Li, Zhengzhou(4); Chen, Xun(5); Chen, Yuyang(2)Source: International Journal of Pattern Recognition and Artificial Intelligence Volume: 34 Issue: 1 DOI: 10.1142/S0218001420540014 Published: January 1, 2020Abstract:Based on the process of generating HDR images from LDR image sequences with different light exposures in the same scene, a new fitting method of camera response curves is proposed to solve the problem that the boundary of the fitting algorithm of camera response curves will be blurred and it is difficult to determine and verify the accuracy of the fitting curves. The optimal response curve is fitted by increasing LDR images step by step through considering the pixel value and texture characteristics. In order to validate the fitting effect of curves, we compare the photographed images and the real images in different time intervals on the basis of HDR images and response curves. We use RGB and gray image experiments to compare the current mainstream algorithms and the accuracy of our proposed algorithm can reach 96%, which has robustness. ? 2020 World Scientific Publishing Company.Accession Number: 20192206978505 -
Record 116 of
Title:A Model of High-Dimensional Feature Reduction Based on Variable Precision Rough Set and Genetic Algorithm in Medical Image
Author(s):Tao, Zhou(1); Huiling, Lu(2); Hu, Fuyuan(3); Qiu, Shi(4); Cuiying, Wu(5)Source: Mathematical Problems in Engineering Volume: 2020 Issue: DOI: 10.1155/2020/7653946 Published: 2020Abstract:Aiming at the shortcomings of high feature reduction using traditional rough sets, such as insensitivity with noise data and easy loss of potentially useful information, combining with genetic algorithm, in this paper, a VPRS-GA (Variable Precision Rough Set - Genetic Algorithm) model for high-dimensional feature reduction of medical image is proposed. Firstly, rigid inclusion of the lower approximation is extended to partial inclusion by classification error rate β in the traditional rough set model, and the ability dealing with noise data is improved. Secondly, some factors of feature reduction are considered, such as attribute dependency, attributes reduction length, and gene coding weight. A general framework of fitness function is put forward, and different fitness functions are constructed by using different factors such as weight and classification error rate β. Finally, 98 dimensional features of PET/CT lung tumor ROI are extracted to build decision information table of lung tumor patients. Three kinds of experiments in high-dimensional feature reduction are carried out, using support vector machine to verify the influence of recognition accuracy in different fitness function parameters and classification error rate. Experimental results show that classification accuracy is affected deeply by different weight values under the invariable classification error rate condition and by increasing classification error rate under the invariable weigh value condition. Hence, in order to achieve better recognition accuracy, different problems use suitable parameter combination. ? 2020 Zhou Tao et al.Accession Number: 20202508854641 -
Record 117 of
Title:Photonic RF channelizer based on 49GHz soliton crystal microcombs
Author(s):Moss, David J.(1); Morandotti, Roberto(5,6); Mitchell, Arnan(2); Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang Y.(1); Boes, Andreas(2); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4)Source: TechRxiv Volume: Issue: DOI: 10.36227/techrxiv.11965518 Published: March 11, 2020Abstract:We report a broadband radio frequency (RF) channelizer with up to 92 channels using a coherent microcomb source. A soliton crystal microcomb, generated by a 49 GHz micro-ring resonator (MRR), is used as a multi-wavelength source. Due to its ultra-low comb spacing, up to 92 wavelengths are available in the C band, yielding a broad operation bandwidth. Another high-Q MRR is employed as a passive optical periodic filter to slice the RF spectrum with a high resolution of 121.4 MHz. We experimentally achieve an instantaneous RF operation bandwidth of 8.08 GHz and verify RF channelization up to 17.55 GHz via thermal tuning. Our approach is a significant step towards the monolithically integrated photonic RF receivers with reduced complexity, size, and unprecedented performance, which is important for wide RF applications ranging from broadband analog signal processing to digital-compatible signal detection. ? 2020, CC BY.Accession Number: 20220143802 -
Record 118 of
Title:Photonic RF channelizer based on a 90 wavelength optical soliton crystal 49GHz Kerr microcomb
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(1); Boes, Andreas(2); Nguyen, Thach G.(2); Chu, Sai T.(3); Little, Brent E.(4); Morandotti, Roberto(5,6); Mitchell, Arnan(2); Moss, David J.(1)Source: arXiv Volume: Issue: DOI: null Published: April 20, 2020Abstract:We report a broadband radio frequency (RF) channelizer with up to 92 channels using a coherent microcomb source. A soliton crystal microcomb, generated by a 49 GHz micro-ring resonator (MRR), is used as a multi-wavelength source. Due to its ultra-low comb spacing, up to 92 wavelengths are available in the C band, yielding a broad operation bandwidth. Another high-Q MRR is employed as a passive optical periodic filter to slice the RF spectrum with a high resolution of 121.4 MHz. We experimentally achieve an instantaneous RF operation bandwidth of 8.08 GHz and verify RF channelization up to 17.55 GHz via thermal tuning. Our approach is a significant step towards the monolithically integrated photonic RF receivers with reduced complexity, size, and unprecedented performance, which is important for wide RF applications ranging from broadband analog signal processing to digital-compatible signal detection. Copyright ? 2020, The Authors. All rights reserved.Accession Number: 20200559867 -
Record 119 of
Title:RF and Microwave Fractional Differentiator Based on Photonics
Author(s):Tan, Mengxi(1); Xu, Xingyuan(1); Corcoran, Bill(2); Wu, Jiayang(1); Boes, Andreas(3); Nguyen, Thach G.(3); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6,7); Mitchell, Arnan(3); Moss, David J.(1)Source: IEEE Transactions on Circuits and Systems II: Express Briefs Volume: 67 Issue: 11 DOI: 10.1109/TCSII.2020.2965158 Published: November 2020Abstract:We report a photonic radio frequency (RF) fractional differentiator based on an integrated Kerr micro-comb source. The micro-comb source has a free spectral range (FSR) of 49 GHz, generating a large number of comb lines that serve as a high-performance multi-wavelength source for the differentiator. By programming and shaping the comb lines according to calculated tap weights, arbitrary fractional orders ranging from 0.15 to 0.90 are achieved over a broad RF operation bandwidth of 15.49 GHz. We experimentally characterize the frequency-domain RF amplitude and phase response as well as the temporal response with a Gaussian pulse input. The experimental results show good agreement with theory, confirming the effectiveness of our approach towards high-performance fractional differentiators featuring broad processing bandwidth, high reconfigurability, and potentially reduced sized and cost. ? 2004-2012 IEEE.Accession Number: 20204609475620 -
Record 120 of
Title:Photonic radio frequency and microwave integration based on a multi-wavelength 49GHz Kerr microcomb source
Author(s):Xu, Xingyuan(1); Tan, Mengxi(1); Wu, Jiayang(1); Boes, Andreas(2); Corcoran, Bill(3); Nguyen, Thach G.(2); Chu, Sai T.(4); Little, Brent E.(5); Morandotti, Roberto(6); Mitchell, Arnan(2); Moss, David J.(1)Source: arXiv Volume: Issue: DOI: null Published: April 16, 2020Abstract:We demonstrate a photonic RF integrator based on an integrated soliton crystal micro-comb source. By multicasting and progressively delaying the input RF signal using a transversal structure, the input RF signal is integrated discretely. Up to 81 wavelengths are provided by the microcomb source, which enable a large integration time window of ~6.8 ns, together with a time resolution as fast as ~84 ps. We perform signal integration of a diverse range of input RF signals including Gaussian pulses with varying time widths, dual pulses with varying time intervals and a square waveform. The experimental results show good agreement with theory. These results verify our microcomb-based integrator as a competitive approach for RF signal integration with high performance and potentially lower cost and footprint. Copyright ? 2020, The Authors. All rights reserved.Accession Number: 20200571198